Natural Dog Toothpaste Ingredients

As mentioned above, there’s a very important reason why all the ingredients in a dog toothpaste should be natural. Anything you put in your dog’s mouth will end up in your dog’s stomach. It’s essential to make sure those ingredients are doing good for your dog’s overall health, rather than simply cleaning the teeth but creating even bigger internal problems.

There are several chemicals that are commonly used as ingredients in oral care products. Although many of these compounds have been used for years their long term use can be considered rather harsh on the body compared to organic substances used in all natural dog oral care products. For example grain alcohol and glycerin are fairly harsh substance that should be avoided. Dog oral care products including Plaque Attack and PetzLife are popular dog oral care products with very different formulations. Dog owners should read the ingredients carefully to determine the formulation they believe is the safest for their dog’s health.

Research has discovered particular ingredients that do several positive jobs: they clean the teeth, freshen the dog’s breath and promote overall immunity and health. Bad dog breath is easily treated utilizing new advanced formulations containing the proper substances.
One of these is grape seed extract, one of the super nutrients of dog nutrition. This nutrient works as a powerful antibacterial which kills off bad bacteria (the cause of bad breath) in a dog’s mouth while preserving good bacteria. It’s also a strong antioxidant which helps slow the breakdown of cells in the dog’s body.

Neem oil and thyme oil are two more ingredients you should keep an eye out for when looking for a good dog toothpaste. Like grapes seed extract, they help kill off particular types of bad bacteria which contribute to bad smells in your dog’s mouth.

You should also look for a dog toothpaste or mouth spray that contains a few freshening ingredients. Peppermint oil and rosemary oil are two healthy, natural ingredients which help freshen your dog’s breath.

More Tips for Cleaning Dogs’ Teeth Naturally

The standard method of cleaning dog teeth to treat bad breath in dogs is similar to cleaning your own: with a toothbrush. However, some dogs are resistant to having a brush poked into their mouth. If you own one of these dogs, don’t worry – we’ll explain some of the alternatives as well.

To brush your dog’s teeth, hold the toothbrush in your right hand (or whichever hand your prefer) and put that arm around your dog to hold his body in place. With the left hand, cup under his jaw to hold his head still and get in the right position to peel his gums back. Don’t expect this to go smoothly the first time you try it, but keep attempting this method until the dog plays along.

If he doesn’t get used to the toothbrush, you have a couple of alternatives. One is dog dental wipes. These help remove plaque and food stuck between the teeth, but they’re more gentle than brushing. However, you may find these don’t deal with the problem of bad dog breath.

In that case, there are sprays available which contain all the natural ingredients listed above. These sprays will effectively do the job of killing bacteria and freshening breath.

Ronald Reyns with staff at the University of Wisconsin studied the so-called n → π * – the interaction of different systems for several years. At the moment the group is headed by Derek Wolfson with staff from the University of Bristol. They showed, using the database search of proteins, this interaction occurs in virtually all proteins. When n → π * – the interaction of one of the lone pairs of electrons on the carbonyl oxygen atom of one amino acid overlap with the π-orbital “antisvyazyvyuschey” carbonyl group in the neighboring amino acid.

Due to the fact that participants in the interaction belong to the main chain, no matter which side of the chain will interact. Any amino acid can form a n → π * – interaction, but the ring structure of praline makes it particularly suitable because of restrictions imposed by distance and angles needed for orbital overlap.

It is important that we are dealing with small distances: the α-helix hydrogen bond is between the first and fifth amino acid residues, in contrast, n → π * – there is always interaction between neighboring amino acids. Nevertheless, n → π *-interaction is usually weaker than the hydrogen bond. In addition, scientists found evidence of such a connection in almost any type of secondary structure and even in unstructured parts of proteins.

Reyns believes that this interaction has been neglected for so long due to the fact that people have imagined the structure of the protein, and there was no need for more detailed studies. If you look at the α-helix without quantum mechanics, never think of the n → π *-interaction, notes Reyns.

The work is notable for the fact that it is ready to make a bold statement about the ubiquity of n → π *-interaction, says Neville Kallenbach – Professor, University of New York. This is very dangerous, but, nevertheless, he said the change current views on the chemical bond has the right to life. However, one can argue that the n → π *-interactions are the only explanation for the geometrical features of molecular structure.

Contrary to popular belief – the effects of moderate global warming may not be all bad. For the first time ever, a four year U.S. national assessment has examined the regional impacts of global warming revealing everything from potentially severe droughts to larger crop yields for some farmers.

The report, Climate Changes in the United States, predicts that as greenhouse gases continue to rise at their current rates and trigger extreme climate changes, average temperatures in the U.S. may rise 5 to 10 degrees Fahrenheit in the next century.

The report’s agricultural section projects yield increases for crops such as wheat, barley and most vegetables in regions like the northern plains. But on the downside, this would mean using more pesticides and an increase in the threat of nitrogen-fertilizer runoff into bays. And yes, on a positive note, the warming may take some of the chill out of winter in some areas, but when temperatures rise in the summer, the warming may lure disease-bearing mosquitoes and other animal sources of disease.

University of Toronto geography professor Danny Harvey says some of the report’s more positive projections should not detract from the many potential dangers of global warming. “A small amount of warming could have positive effects, but if we don’t take preventative action then we will end up not with a small amount of warming but a large amount of warming,” says Harvey. “A one or two degree of warming may have positive impacts in some areas but, a five to seven degree of warming could have very negative impacts.”

The report used computer climate models to predict the profound changes that may greatly transform regions, like the threat of drought in the Southeast and increased rainfall in parched areas of the Southwest. But some critics believe that computer models cannot accurately predict the impact of global warming on a regional basis.

Harvey thinks that these skeptics are missing the larger issue. “The things we’re most concerned about depend on very basic fundamental principals,” says Harvey. “We can say that drought risk will increase in the interior of continents and that does not depend on the details of any models. The point is that there is an overall risk.”

Although the U.S. report was the first that examined American regions on an in-depth scale, Environment Canada has been examining the regional impact of global warming for some time. Recent study by Canada Country Study (CCS) revealed many possible global warming consequences for Canada, including floods and droughts in southern British Columbia and coastal erosion in the Atlantic region. The six part national assessment examined the impacts of climate change on Canada as a whole and suggested modes of action as well as issues that need further research.

Roger Street, director of the adaptation and impacts research group for Environment Canada, says both the positive and negative issues that were uncovered in the Canadian study have to be put into context. “Having temperatures warm up in the winter cannot be all negative but even from this perspective we have to understand what could be positive for one community may be negative for another,” says Street, the study’s lead coordinator. “Warmer winters might be good for some but what happens to those communities that rely on snowfall or winter recreation?”

Street adds that many of the regional effects that are projected in the U.S. report were also stated in the CCS – one of the main concerns being a fresh water shortage. Both assessments also project that rain will fall heavily in some regions followed by long dry spells, bringing about flash flood weather patterns.

Street says that one of our hopes for dealing with global warming in Canada lies in the rate at which it is happening. “The slower the rate of change occurs and the less the rate of change occurs the more chance we have to adapt and develop coping technologies,” says Street. “Slow change will allow natural systems and human activities to adapt to changes.”

You remember Velociraptor: it’s the smallish, but deadly meat-eater featured prominently in Jurassic Park and its two sequels. In the movies, this predator is portrayed as fierce, and cunning — a dinosaur as smart as a dolphin or chimpanzee. But according a prominent paleontologist, you really can’t believe everything you see on the big screen. In fact, velociraptor probably couldn’t outwit a modern-day lap dog.

“If we compare its brain vs. body size, scaled for weight, to modern animals, it is at the very bottom level of modern birds and mammals,” he adds. “Velociraptors are comparable to an emu or an opossum.”

So where did the ‘raptor get its intellectual image? Well, says the scientist, it was something of a genius for its time (the late Cretaceous period), even compared to its contemporary mammals.

But being a genius of the late Cretaceous isn’t saying much.

“They were probably a lot smarter than modern reptiles or snakes,” the paleontologist says. “But a cat, dog or eagle would probably be smarter than a Velociraptor. Dolphins are way out, and chimpanzees are vastly smarter.”

That’s not to say Velociraptor wasn’t dangerous. As he points out, a crocodile is a lot dumber than a lion or tiger but it will kill you just as easily. The real Velociraptor was smaller than it’s portrayed in the movies, however. It was coyote-sized with its tail comprising half its two-meter length. And it had lots more feathers too, probably used for display, making it look something like a really tough peacock.

However, there’s indirect evidence Velociraptors made themselves more efficient killers by hunting in packs. Paleontologists have found multiple, individual fossils of Velociraptor’s close North American relative, Deinoychus, along with a prey dinosaur they were eating, a finding suggestive of predatory team-work.

“The prey dinosaur is a herbivore called Tenontosaurus, a primitive relative of the duck-bills that was about ten times as big as each Deinonychus,” he explains. “The thought is Deinoychus would be too small to take down one of these guys individually, but working as a team they could have, like a pack of wolves after a moose or lions after a water buffalo.”

So we could extrapolate pack-hunting-ability to other dromaeosaurs — the group that includes both Velociraptor and deinoychus — although the scientist is cautions that it’s not a sure thing.

“When you look at lions and tigers, it’s hard to tell their skeletons apart, their bones are almost identical,” he points out. “But lions have very sophisticated pack hunting while tigers are solitary – and we wouldn’t know that from individual skeletons. So it’s within their ability, but whether Velociraptor actually did it is not established.”

What is established is how Velociraptor killed: a Velociraptor fossil has been found with what was going to be its last meal, a primitive horned dinosaur called Protoceratops.

“The Velociraptor has the head of the Protoceratops gripped with one claw and the other hand’s sickle-shaped claw is stuck deep in it’s neck, just a few millimeters from the bone,” he concludes. “So it seems clear that it would grab its prey and rip out its throat and belly with the claw. Although in fairness, the Protoceratops had the Velociraptor’s other hand in its beak so its final move would probably be to close its jaws and snap off Velociraptor’s arm. They would have wound up killing each other.”

OBJECTIVES
Grades 5 – 8
°Become familiar with the microscope and its proper use.
°Prepare wet mount plant and animal slides.
°Observe prepared slides.
°Study diffusion and osmosis using dialysis tubing.
°Observe the stages of mitosis and understand that nuclear division is an important part of the cell cycle.

Grades 9-16
°Prepare slides and study the response of plants to changes in their osmotic environment.
°Examine a mite that is a normal inhabitant of human hair follicles.
°Observe stomates in the lower epidermis of a leaf and use counts of stomates in order to estimate the number in the entire leaf.
°Calculate the time needed for one cell cycle. The learner will understand cell growth and reproduction that occurs through mitosis and cytokinesis.

SCIENCE PROCESS SKILLS
Observing
Comparing
Inferring
Questioning
Applying
Hypothesizing
Collecting/Analyzing data
Logical thinking
Modeling
Writing scientifically
Designing an experiment
Forming conclusions

AAAS SCIENCE BENCHMARKS
5A Diversity of Life
5CCells
6CBasic Function

STATE SCIENCE CURRICULUM FRAMEWORKS
Grades 5 – 8
4.1.9Describe similarities/differences between single celled and multi- celled organisms.
4.1.10Explain how cells use food as a source of energy.
1.1.13Generate conclusions based on evidence.

Grades 9-12
2.1.15Analyze how scientific technology provides new tools for solving problems in all disciplines.
4.1.20Describe and explain the complexity of cellular structure and function (i.e., organelles, biochemistry, metabolism, photosynthesis, membrane functions, cell division).

SCIENCE EDUCATION STANDARDS (NCR)
Grades 5 – 8
Structure/Function in Living Systems
Reproduction and Heredity
Populations and Ecosystems
Diversity and Adaptations of Organisms

Grades 9-12
The Cell
HeredIty
Matter, Energy, Organization of Living Systems
Evolution of Living Systems
Biosphere and Interdependence

MATERIALS
Compound light microscope
Water source
Prepared animal and plant cell slides
Methylene blue stain
Toothpicks
Microscope slides
Covers lips
Droppers
Microscopes
Paper towels
Microscope immersion oil or mineral oil
Cardboard sheet or stiff index card
Oil of clove
Geranium plant leaves
15 cm plastic ruler
Dialysis tubing
20 cc syringe
15% glucose/2% starch solution
(15 grams of glucose, 2 grams of starch and 100 ml of water).
(This is enough solution for six groups.)
Iodine solution
(90 ml of water and 4 ml iodine)
Glucose testape
Plastic cups (large enough to hold 250 ml of water)
Triple beam balance
Salt solutions: 10% NaCl
Distilled water
Living Elodea leaves

KEY QUESTIONS
1.How are cells structured?
2.Explain how cells grow and divide.
3.What is the mechanism for cellular reproduction?
4.How do diffusion and osmosis differ?
5. What is dialysis?
Activity 1- Microscope use [The instructor should demonstrate as the students practice.]

Care of the Microscope
1.Carry the microscope in an upright position, one hand under the base, the other hand around the arm.
2.Do not permit excess electrical cord to dangle; leave some of the cord wrapped around the microscope.
3.Clean the lenses each time you use the microscope. Always use lens paper.
4.Report any difficulties with the microscope to the instructor.
5.Do not remove any part(s) of the microscope.
6.Do not allow the objective lens to strike the stage or slide/coverslip. 7.To store the microscope:
A.Turn nosepiece to the lowest power objective.
B.Wrap the cord around the microscope.
C.Cover.

Identification of Microscope Parts Using the table and the microscope diagram that follows, find and try out the various parts.
PartNameJob or Function
Aeyepiece/ocularholds top lens, usually lOx magnification through which object is viewed
Bbody tubesholds top lens, connects eyepiece to
objectives
Carmsupports body tube, a handle for carrying
Dnosepieceholds the objective lenses, turns to specific
objective
Ehigh powerobjective contains lens usually 40x, longest objective
on the nose iece, greatest detail
Fmedium power objectivecontains lens usually lOx, medium length if
3 objects are present, greater detail
Glow objectivecontains lens usually 4x, shortest length to
locate some detail
HCoarse adjustment moves body tube or stage up and down,
IFine adjustmentThe only adjustment used with high power.
JStageSupports the slide
Kstage clipsholds the slide in place
Ldiaphragm iris or diskcontrols the amount of light that enters the
microscope
Mlight sourceelectric lamp that provide the light into the
microscope
Nbasesupports the microscope, and used when
you carry the microscope
Ostage opening/apertureallows light to enter into the objectives

Use of the Microscope when using the microscope for the first time:
1.Turn on the microscope.
2.Look through the eyepiece. The cicle of light you see is called the field of view. Turn the diaphragm as you look through the eyepiece. You should notice that the light gets brighter or dimmer. Adjust the diaphragm with each specimen to determine the be st setting for that specimen.
3.Turn the nosepiece to change the objective lens. You should feel and/or hear a click as the objective is moved into place. Always start with the lowest power objective.
4.With a monocular microscope only one eye is used. Learn to work with both eyes open. If you have difficulty, hold your hand over one eye. It will be easiest to look through the microscope with your dominant eye.
5.The compound light microscope combines the magnifying power of two lenses. Total magnification equals the eyepiece magnification times the objective magnification. (eyepiece) x (objective) = total magnification. The eyepiece is usually lOX, the objectiv es are usually 4x, lOX, and 40X

The following procedure should always be used when observing any specimen under the microscope:

1.Start with the lowest power objective. Lower it as far as it will go.
2.Place the slide, prepared or temporary, on the stage. Be sure to use a cover slip.
3.Center your specimen over the stage- aperture. Raise the stage while looking through the eyepiece until you see the blurry image of the specimen.
4.Adjust the coarse focus, then fine tune with the fine focus. Remember to use the coarse focus only on low power.
5.Switch to medium power, adjust with the fine focus. Parfocal microscopes can switch directly from one objective to another without danger of hitting the slide.
6.Switch to high power, adjust the fine focus.

Making a temporary wet-mount slide (Figure 1)
1.Place a drop of water on a clean slide.
2.Place the specimen in the drop of water.
3.Position a cover slip at an angle over the specimen and gently lower into place.
4.Place slide on microscope stage and examine under low power.

Questions
a.why should you use a wet mount slide when viewing living cells?
b.why should the coverslip be lowered gently at an angle rather than being dropped on top of the specimen to be viewed?

Hints for Successful Microscope Observations
PROBLEMSOLUTION
Field of vision appears blackCheck to be sure that objective has clicked into position
Image appears fuzzy or unclearCheck eyepiece. Rotate it. Clean if
necessary.
Dirty eye iece or objectiveClean it.
Inability to locate specimenLower magnification. Recenter
specimen
Lack of sharp imageCheck to see that cover slip is on top
of slide
Too much or not enough light intensityAdjust diaphragm.
EyestrainObserve with both eyes open.
Out of focusAdjust focus frequently.
Inadequate observationScan all preparations by moving slide from side to side and up and down.

1.Place a drop of solution (stain, distilled, or salt water, etc.)
2.On the other side of the cover slip, put a piece of paper towel under the cover slip.
3.Allow the paper towel to draw the excess from under the cover slip.

Rules for microscope drawings
1.Pencil with shading or natural color with colored pencils.
2.Unlined paper, use one side only, leave at least a one inch margin on all sides.
3.Print all labels.
4.Three to four drawings per page maximum.
5.Draw and label only what you see through the microscope.

Pulling solutions across a wet-mount slide (Figure 2)
Activity 2- Cell observation

Materials
Paper towels
Coverslips
Eyedroppers
Microscope slides
Probes
Razor blades
Toothpicks
Unlined paper
Food coloring
Cork and/or bamboo
Methylene blue stain
Two or more colors of threads
Purple and yellow onion
Pencils and/or colored pencils
IKI/iodine stain
Assorted prepared slides such as:
Amoeba, paramecium, euglena, spirogyra, ulothrix, cholella, butterfly winds, insect eyes/mouth parts/legs, ox neuron, frog blood, etc.

Safety Considerations
°Breakage of glass slides and coverslips.
š IKI and methylene blue are toxins.
°Care should be taken in handling and using probes, razor blades, scissors, and toothpicks.
°Keep electrical connections dry and take care while plugging in or unplugging.

Procedures:
Make wet-mount slides of the following specimens. Observe them first on low power then on high power. Draw a representative cell on high power and label visible structures. Follow the directions given previously for making a wet-mount slide and for a dding solutions to a wet-mount slide.

1.Crossed Threads
Position two different colored threads (red, green) in an X on a clean slide. As you practice focusing note that because they are at different depths on your slide, both threads will not be in focus at the same time. This depth of field will also be n oticeable in cells viewed under the microscope.

2.Cork or Bamboo Cells
Shave a thin section from a piece of cork or bamboo, make a wet-mount slide and observe. A bottle cork, an old bamboo reed from a wind instrument, or fresh bamboo may be used. Note that in the dead cells, you will only see cell wall.

3.Onion Cells
Pull off the dry brown outer layer of a white or yellow onion and discard. Peel off a piece of the thin inner skin from between the thick layers of the onion and place it on a dean slide. Be careful to keep the tissue flat and in one layer. Put a drop of yellow food coloring or a drop of IKI (iodine) solution on the onion tissue. Wait a few seconds and blot the excess gently with a corner of paper towel. The cell and its structures will show up better after being stained. You should be able to see the cell wall, cytoplasm, and the nucleus. The cell membrane is directly inside the cell wall.
To see the cell membrane, compare fresh onion skin with onion skin that has been peeled off for around thirty minutes. The old onion will have dehydrated and the membrane and cytoplasm shrunk toward the center.

Questions
a.what differences do you notice between the unstained and stained slides?
b.what organelles, if any, can you see in the stained slide that you could not see in the unstained slide?

4.Purple onion
Repeat step three using a purple onion. Staining will not be necessary.

5.Cheek Cells
With the flat edge of a toothpick, gently rub the inside of your cheek. Smear the collected cell debris into a drop of water on a clean slide. Stain using methylene blue, iodine, or food coloring. You should be able to see the nucleus, cytoplasm, and cell membrane.

6.Stem Cross-Section
Slice as thin a section as possible from a fresh woody twig. Pace the section on a slide and observe it unstained, then stained with iodine, methylene blue or food coloring ring. Repeat with an herbaceous stem. You should be able to see various cells and tissue layers.

7.Prepared Slides
Observe various prepared slides (see materials list).

Typical Eukaryotic Cell Structures

Cell Parts

Nucleus
Nucleolus

Nuclear envelopes
pores
Chromosomes
Cell membrane

E.R.
smooth E.R
rough E.R.
Ribosomes
amino adds
Mitochondria
Vacuole
Vessicle
Lysosome
Golgi
Centriole

Microtubules
Chloroplast

Cell wall

Cytoplasm
Size (microns)

5-7
2

0.12-0.14
0.125
0.0024
0.006

0.01-0.08
0.01-0.08
0.01-0.08
0.025
0.0008
1.5-0.5
0.1
0.1
0.1
1-0.5
0.2-0.4

0.02-0.05
5.5-2

1-1.3

whole cell
Functions

šcommand center for cell activities and protein synthesis.
šproduces ribosomes and RNA
šregulateslates material entering and leaving nucleus.

šControls heredity
š controls materials entering and leaving cells
š lipid synthesis
šprotein synthesis
š protein synthesis
šbuilding blocks for protein
š cellular respiration produces energy from ATP

šstores water,minerals, food, waste

š membrane bound sac transports material

š garage collector in cell, cellular digestion

špackage material for export

šanimal cells only, microtubular organizing
center. i.e. Mitosis spindles and asters
šstructure and cytoplasmic streaming

š photosynthetic center of cell, contains chlorophyll. plant onl

šplant only, made cellulose
šmost cell activities occur
Activity 3
Observation of an animal living on the human skin: Follicle mites

Purpose
To examine a mite that is a normal inhabitant of human hair follicles.

Materials
Compound microscope
Two or more glass slides
Two or more glass cover slips
Toothpicks
Microscope immersion oil (or mineral oil)
A thin piece of cardboard (back of notepad, etc.)

Background Information
Animals come in all shapes and sizes. Some of the multicellular animals with complex and variously specialized organ systems are hardly larger than some of the one celled protozoans. Mites of the genus Demodex are closely related to the spiders and ticks, but are so small that they can live within the human hair follicle and feed on the follicular cells and the oils produced by the glands associated with the hair. The two species found on humans, D. folliculorum and D. brevis, do not commonly cause problems to their hosts, in fact, they are far less numerous in individuals with skin disorders such as acne. In some older people, D. folliculorum has been suspected of causing irritation and a reddening of the skin near the eye bro ws and lower forehead, painful but not severe. However, the related mite that occurs on dogs, D. canis, can cause demodectic mange, a rather severe skin condition. Numerous D. folliculorum may be found in a single follicle, but only one D. < I>brevis is found in an oil gland. Passage of mites from person to person is by direct contact.

Procedure

1.Clean a slide and cover slip. Place one drop of immersion oil or mineral oil onto the slide.

2.With one hand pull the skin of your forehead tight. Taking the card in the other hand press the edge of the card firmly against the skin and scrape it across your forehead. Remember, you are expressing oils and mites from the pores and follicles of the skin, so the firmer the pressure, the more likely you are to find mites. Best results are obtained by using the edge of a glass slide, but extreme care must be used to avoid breaking the slide and cutting yourself.

3.With the toothpick, remove the oily mass you have collected on your car and stir it into the drop of immersion oil on the slide. Place a cover slip over the drop.

4.Examine the slide under lOOX and change to 400X magnification when a suspected mite is observed. These mites are small, but easily seen under lOOX. The 400X is required only to examine the details of their structures.

5.It may be necessary to make more than one slide to determine how much pressure on the card is required to express the mites. However, everyone has some skin mites, so given patience, success should be virtually assured.

6.Good hunting!

To observe stomates in the lower epidermis of a leaf and to use stomatecounts under high power fields of view to estimate the total number in one leaf.

Activity 4- Gas exchange and photosynthesis

Purpose

Background Information
During photosynthesis CO2 and H2O are used as raw materials in the production of glucose. Light energy and enzymes are required in order for photosynthesis to occur. As water molecules are split providing electrons and H+ used in photosynthesis, oxyge n molecules are released. Most photosynthesis occurs in chIoroplasts in the mesophyll (middle) layers of the leaf. CO2 diffuses into the mesophyll region through stomata (small openings) in the leafs epidermal layers. Oxygen diffuses outward through th e stomates during photosynthesis. During periods of darkness with no photosynthesis and only cell respiration occurring, the direction of diffusion is reversed. Water diffuses into the mesophyll region from xylem cells in the veins providing a continuous flow of water from root hairs to the leaves. During any period when the stomates are open, water will diffuse outward from the leaf (transpiration). Opening and closing of stomata are controlled
In this activity, a portion of the lower epidermis will be removed from a leaf, and the stomates, with the surrounding guard cells, will be observed and counted. The total number of stomates in the lower epidermis of the entire leaf will be estimated from these counts.

Procedure
A.Number of Stomates
1. Tear a leaf at an angle while holding the lower surface upward. The tearing action should peel off a portion of the lower epidermis. It will appear as a narrow, colorless zone extending beyond the green part of the leaf.
2. Using forceps, tear off a small piece of this epidermis. immediately place it in a drop of water on a slide. Add a cover slip. Do not allow the fragment to dry out.
3. Using the low power objective of your microscope, locate some stomates. Then switch to the high-power objectives. Make a drawing to show the shape of a stomate, its guard cells, and a few adjacent cells in the epidermis.
4. Count the number of stomates in 5 high power fields of the microscope and average them. Calculate the average number of stomates per mm2 of leaf surface. This can be done by finding the diameter of the high power field of view and then computing the h igh power field of view area (area = r2). To find the high power diameter, divide the magnification number of the high power objective by that of the low power objective. Then divide the diameter of the low power field of view by this quotient. The resu lt is the diameter of the high power field of view.
5. Measure the total leaf surface area using cm2 grid paper and estimate the total number of stomates in the entire leaf.

Questions
1. What purpose do the guard cells serve?
2. What are the structures visible in the guard cells?
3. Why are there more stomates in the lower epidermis?
4. Can you think of a plant that would have more stomates in the upper epidermis than in the lower epidermis?
5. What plant types would be likely to have the fewest stomates?
Activity 5 – Diffusion and osmosis The life of a cell depends on movement of atoms and molecules. One of the results of this molecular motion is diffusion. Diffusion is the random movement of molecules from a place of higher concentration to a place of lower concentration. The concent ration of molecules at various points between the high and low areas forms a gradient, which is known as the concentration gradient.
Osmosis is the diffusion of water through a selectively permeable membrane. A selectively permeable membrane allows the diffusion of certain solutes and water molecules and restricts the movement of some solute molecules.
When comparing two solutions, the solution with the greater concentration of solutes is the hypertonic solution, while the solution with the lesser concentration of solutes is the hypotonic solution. when the two solutions are divided by a selectively per meable membrane, water molecules move from the hypotonic solution to the hypertonic solution. The solute molecules move from the hypertonic solution to the hypotonic solution. If the two solutions have the same concentrations of solutions are isotonic.

Background Information

Purpose
This activity is designed to observe diffusion and osmosis through a selectively permeable membrane (dialysis tubing). A selectively permeable membrane will allow substances to diffuse at different rates. The movement of a solute through a selectively permeable membrane is called dialysis.

Part A: Diffusion 1.Secretly place a drop of oil of clove in the front corner of the room.
2.Allow the aroma to diffuse through the room until students begin to notice the aroma and comment on it.

Procedure

Questions
1.What part of the room noticed the aroma first?
2.What part of the room noticed the aroma last?
3.Explain how the aroma moved through the room.
Part B: Dialysis

Procedure
All of the molecules of a given substance are about the same size, but the molecules of different substances are different in size. Iodine and water molecules are very small, glucose is larger and starch molecules are very large. A selectively permeable membrane allows some molecules to pass and restricts others. Design an experiment to show dialysis.

Materials
Dialysis tubing
20 cc syringe
15% glucose/2% starch solution
(15 grams of glucose, 2 grams of starch and 100 ml of water) (This is enough solution for six groups.)
Iodine solution (90 ml of water and 4 mi iodine)
glucose testtape
Plastic cups (large enough to hold 250 mL of water)
Water
Triple beam balance

Procedure
1.Using glucose testtape, test the glucose/starch solution. Record the results in the data table.
2.Cut a 30 cm length of dialysis tubing. Soak the tubing in a cup of water for five minutes. Remove the tubing from the water and tie one end.
3.Using the 20 cc syringe, place 15 ml of the glucose/starch in the dialysis bag. Tie the other end of the dialysis bag leaving enough space for expansion.
4.Record the color of the liquid in the bag in the data chart. Mass the bag and record the mass in the data table.
5.Mix 90 ml of water and 4 ml of iodine in a cup. Using glucose testtape, test the iodine solution and record the results in the data table.
6.Mass the cup and its contents. Record the mass in the data table.
7.Place the dialysis bag in iodine-water mixture and allow the setup to stand for thirty minutes. After thirty minutes, remove the dialysis bag from the iodine-water solution. Drain as much of the liquid as possible from the outside of the bag back into t he cup. Blot the dialysis bag dry on a paper towel. Mass the dialysis bag and record the results in the data chart.
8.Mass the cup and iodine solution. Record the results in the data chart.
9.Observe the color of the contents of the dialysis bag and the cup and record this information in the data table.
10.Using glucose testtape, test the liquid in the dialysis bag and in the cup and record the results in the data table.
11.Calculate the percent change in mass of the dialysis bag and of the cup (% Change in mass = (Final mass – Initial mass)/Initial Mass x 100).
Note:If water enters the bag, there will be a positive value for % change in mass. If water leaves the bag, there will be a negative change in mass. The same will be true for the cup.
DATA TABLE

InitialInitialFinal% ChangeFinal
ContentsColorMassTestapeColor
MassTestapeIn MassContents

Bag

Cup
Questions
1.Which substance(s) are entering the dialysis bag and which are leaving the bag? What evidence do you have to support this answer?
2.Which substance(s) did not pass through the membrane? Give supporting evidence for your answer.
3.Did water move in this experiment? What evidence do you have for the movement?
4.Referring to your experiment, were you correct? If you were incorrect, rewrite it to account for your observations.
5.Was the dialysis bag selectively permeable? Give evidence to support your answer.
6.Predict the effect of temperature on your experiment of…

Increasing the temperature:
Decreasing the temperature:
 To examine the response of plants to changes in their osmotic environment.

Activity 6- Membrane responses of living organisms

Purpose

Materials
Compound microscope
Slides and cover slips
Salt solutions 10% NaCl
Distilled water
Living Elodea leaves

Background Information:
In a healthy plant cell, isotonic with its environment, the cytoplasm, chIoroplasts, and other cell organelles are pressed against the rigid cell wall by a large central vacuole filled with water applying turgor pressure to the contents. The size of the central vacuole changes as water passes into or out of the cell in response to differing environmental conditions. when the plant is in a dry environment, the fluid outside the cell becomes more concentrated (hypertonic) than the cytopla sm, water passes out of the cell by osmosis, the vacuole becomes smaller, and the cytoplasm shrinks away from the cell wall. This process of cell shrinkage in plants is called plasmolysis. The combined shrinkage of all the plant’s cells cause it to appear wilted. when water is taken up by the plant, the fluids outside the cell become more dilute than the cytoplasm and water enters the cell, the vacuole increases in size, the cytoplasm becomes pressed against the cell wall by increased turgor pressu re, and the plant regains its unwilted shape. Since the central vacuole is the first cellular structure to gain or lose water, its size and effect on the positions of other cellular structures can be used as in indicator of the osmotic conditions with the plant cell.

Procedure
1.Make a temporary wet amount of an Elodea leaf using water from the plant’s container.
2.Cover with a cover slip and observe the distribution of cellular structures (chIoroplasts will be particularly visible) under low and then high power. Best results will be obtained in the thin area where the leaf was torn from the plant.
3.Place a drop of 10% salt solution on the side of the cover slip. On the other side of the cover slip, put a piece of paper towel under the cover slip (See Figure 2 in Activity 1). Allow the paper towel to draw the salt solution under the cover slip by c apillary action Observe the distribution of the chloroplasts as before. If no change occurs within a few minutes add another drop of 10% salt solution and draw it under the cover slip as before. Continue to observe the cells for up to 15 minutes.

Questions
1.Why do we use water from the plant’s container?
2.What changes would you expect to observe? what do you observe? Explain the results.
3.Is the 10% salt solution hypertonic or hypotonic to cellular contents?

Procedure
4.Place a drop of distilled water at the edge of the cover slip and draw it under the cover slip by capillary action, as before. Continue to add distilled water while observing the cells for changes in vacuole size for up to 15 minutes.

Questions
1.How is the salt concentration of the medium surrounding the leaf?
2.What do you expect to observe in the cells? what do you observe? Explain.

Activity 7- The cell cycle To identify cell cycle stages and estimate the time needed for one cell cycle.

Purpose

Background Information
The cell cycle includes both the period of time for the division of the nucleus (mitosis) and the period of time for cell growth and chromosome duplication. Interphase is the cell cycle stage between mitotic divisions during which cell growth and chromosome duplication occurs. Mitosis includes four cell cycle stages: prophase, metaphase, anaphase, and telophase. During prophase, the chromosomes become distinguishable as they condense. A spindle forms, and the nuclear membrane br eaks down. During metaphase, the chromosomes become arranged near the center of the cell. The chromatids of the chromosomes separate and move to opposite ends of the cell in anaphase. Cell division is completed in telophase as the cy toplasm divides (cytokinesis), the nuclear membrane reforms, and the two daughter cells separate.
Cell division in plants occurs in meristem tissue located in buds, cambium, and root tips. Of these regions of growth, the greatest number of dividing cells can be seen at the root tip. You will observe sections of Allium (onion) root tip. Toward t he main plant body the cells have grown to full length and are no longer dividing. Near the root tip, however, is the root apical meristem, a region of rapid cell division. Among the small cells of the root meristem you should be able to find cells in all stages of the cell cycle.
Unllke plants, which grow only in certain areas, animal growth occurs in various tissues throughout the body. Some cells in the human body are continuous replicators or are cell populations that continuously run the cell cycle. Examples of continuous repl icators would be skin, gastrointestinal lining, bone marrow, and hair follicles.
Some other cell types become incapable of continued cell division and are called non-replicators. Examples of these types of cells would be brain cells, heart muscle cells, and skeletal muscle cells.
A third class of cells are the occasional replicators. These cells normally do not undergo cell cycle but are capable if stimulated to do so. The most popular example of this kind of replicator is the liver cell. Liver cells normally do not divide. Howe ver, if part of the liver is surgically removed, the “stump” can regenerate the missing part by the re-initiation of the cell cycle in the “stump” liver cells. The cell cycle continues until there is complete replacement of what was surgically removed. As an animal matures, its rate of cell division declines; therefore, cell division is most common in embryos shortly after fertilization. For these observations, use a prepared slide of a whitefish blastula (a blastula is an early stage in development). A t this stage, the embryo is largely a mass of dividing cells. Four slices of about one hundred cells each were placed on each slide and stained. Among these sections you can find cells in all of the stages of the cell cycle.

Part A: Identification of the mitotic phases

Procedure

1.Using the Allium root tip slide, locate, sketch, and label cells in interphase, prophase, metaphase, anaphase, and telophase. Also notice the manner of cytokinesis, i.e., the formation of a new cell wall, called a cell plate, between the t wo new nuclei.
2.Using the whitefish blastula slide, locate, sketch, and label cells with nuclei in interphase, prophase, metaphase, anaphase, and telophase.

Part B: Calculation of cell cycle time
The chemical colchicine stops nuclear divisions at metaphase, but affects no other stage of the cell cycle. This can be used in attempts to determine the time needed for a full turn of the cell cycle. This can be used in attempts to determine t he time needed for a full turn of the cell cycle. First, the percentage of nuclei in metaphase of untreated tissue is determined (This value is about 1%). Living material is then treated for a specific time of 30 minutes (T) with colchicine. Slides of t he colchicine treated material are prepared, and again the percentage of metaphase nuclei is determined. The change in percentage over this specific time (T) relates to the overall time of the cell cycle as follows:

_____ % metaphase (colchicine treated cells)

_____-1% metaphase (normal cells)
=Q
T(time) = Q % of total cycle

Therefore, T/Q % = time of entire cell cycle

For example, if cells were treated for 30 minutes and (% treated) – (% normal) = 20%, then T/Q = 30 min/0.20 = 150 minutes for the entire cell cycle.

Procedure
1.The slides available in lab are of onion root tips treated for 30 minutes with colchicine. In normal tissue the percentage of nuclei in metaphase would be 1%. Two students work together, one as an observer and one as a recorder. The observer ranges up and down three central vertical rows of cells visible within the field at one time and identifies the cell cycle stage for each cell. The recorder records the data in the table below. Four such field counts should be made, with the observer and recorde r changing roles alter the second count. It is suggested that only the three most central rows be counted in each field.

Field Count

Phase1234Totals

prophase
_______________________________________________________________

metaphase
_______________________________________________________________

anaphase
_______________________________________________________________

telophase
_______________________________________________________________

interphase
_______________________________________________________________

Sum of all totals = ______ 2.Now divide the total of all metaphase cells by the total of all phases combined. This gives the percentage of 30 minute colchicine treated cells in metaphase. From this, subtract 1%, the percentage of untreated cells in metaphase. The normal length of the cell cycle can be calculated as shown above.

The length of the cell cycle for onion root tip cells is ___________

• The human genome contains 3 billion chemical nucleotide bases (A, C, T, and G).
• The average gene consists of 3000 bases, but sizes vary greatly, with the largest known human gene being dystrophin at 2.4 million bases.
• The functions are unknown for more than 50% of discovered genes.
• The human genome sequence is almost (99.9%) exactly the same in all people.
• About 2% of the genome encodes instructions for the synthesis of proteins.
• Repeat sequences that do not code for proteins make up at least 50% of the human genome.
• Repeat sequences are thought to have no direct functions, but they shed light on chromosome structure and dynamics. Over time, these repeats reshape the genome by rearranging it, thereby creating entirely new genes or modifying and reshuffling existing genes.
• The human genome has a much greater portion (50%) of repeat sequences than the mustard weed (11%), the worm (7%), and the fly (3%).
• Over 40% of the predicted human proteins share similarity with fruit-fly or worm proteins.
• Genes appear to be concentrated in random areas along the genome, with vast expanses of noncoding DNA between.
• Chromosome 1 (the largest human chromosome) has the most genes (2968), and the Y chromosome has the fewest (231).
• Genes have been pinpointed and particular sequences in those genes associated with numerous diseases and disorders including breast cancer, muscle disease, deafness, and blindness.
• Scientists have identified about 3 million locations where single-base DNA differences occur in humans. This information promises to revolutionize the processes of finding DNA sequences associated with such common diseases as cardiovascular disease, diabetes, arthritis, and cancers.

genome-initial studies

A Brief Overview

Though surprising to many, the Human Genome Project (HGP) traces its roots to an initiative in the U.S. Department of Energy (DOE). Since 1947, DOE and its predecessor agencies have been charged by Congress with developing new energy resources and technologies and pursuing a deeper understanding of potential health and environmental risks posed by their production and use. Such studies, for example, have provided the scientific basis for individual risk assessments of nuclear medicine technologies.

In 1986, DOE took a bold step in announcing the Human Genome Initiative, convinced that its missions would be well served by a reference human genome sequence. Shortly thereafter, DOE joined with the National Institutes of Health (NIH) to develop a plan for a joint HGP that officially began in 1990. During the early years of the HGP, the Wellcome Trust, a private charitable institution in the United Kingdom, joined the effort as a major partner. Important contributions also came from other collaborators around the world, including Japan, France, Germany, and China.

Ambitious Goals

The HGP’s ultimate goal was to generate a high-quality reference DNA sequence for the human genome‘s 3 billion base pairs and to identify all human genes. Other important goals included sequencing the genomes of model organisms to interpret human DNA, enhancing computational resources to support future research and commercial applications, exploring gene function through mouse-human comparisons, studying human variation, and training future scientists in genomics.

The powerful analytic technology and data arising from the HGP raise complex ethical and policy issues for individuals and society. These challenges include privacy, fairness in use and access of genomic information, reproductive and clinical issues, and commercialization (see p. 8). Programs that identify and address these implications have been an integral part of the HGP and have become a model for bioethics programs worldwide.

A Lasting Legacy

In June 2000, to much excitement and fanfare, scientists announced the completion of the first working draft of the entire human genome. First analysis of the details appeared in the February 2001 issues of the journals Nature and Science. The high-quality reference sequence was completed in April 2003, marking the end of the Human Genome Project—2 years ahead of the original schedule. Coincidentally, this was also the 50th anniversary of Watson and Crick’s publication of DNA structure that launched the era of molecular biology.

Available to researchers worldwide, the human genome reference sequence provides a magnificent and unprecedented biological resource that will serve throughout the century as a basis for research and discovery and, ultimately, myriad practical applications. The sequence already is having an impact on finding genes associated with human disease (see p. 3). Hundreds of other genome sequence projects—on microbes, plants, and animals—have been completed since the inception of the HGP, and these data now enable detailed comparisons among organisms, including humans.

Many more sequencing projects are under way or planned because of the research value of DNA sequence, the tremendous sequencing capacity now available, and continued improvements in technologies. Sequencing projects on the genomes of many microbes, as well as the honeybee, cow, and chicken are in progress.

Beyond sequencing, growing areas of research focus on identifying important elements in the DNA sequence responsible for regulating cellular functions and providing the basis of human variation. Perhaps the most daunting challenge is to begin to understand how all the “parts” of cells—genes, proteins, and many other molecules—work together to create complex living organisms. Future analyses on this treasury of data will provide a deeper and more comprehensive understanding of the molecular processes underlying life and will have an enduring and profound impact on how we view our own place in it.

DNA from all organisms is made up of the same chemical and physical components. The DNA sequence is the particular side-by-side arrangement of bases along the DNA strand (e.g., ATTCCGGA). This order spells out the exact instructions required to create a particular organism with its own unique traits.

The genome is an organism’s complete set of DNA. Genomes vary widely in size: the smallest known genome for a free-living organism (a bacterium) contains about 600,000 DNA base pairs, while human and mouse genomes have some 3 billion .Except for mature red blood cells, all human cells contain a complete genome.

DNA in the human genome is arranged into 24 distinct chromosomes–physically separate molecules that range in length from about 50 million to 250 million base pairs. A few types of major chromosomal abnormalities, including missing or extra copies or gross breaks and rejoinings (translocations), can be detected by microscopic examination. Most changes in DNA, however, are more subtle and require a closer analysis of the DNA molecule to find perhaps single-base differences.

Each chromosome contains many genes, the basic physical and functional units of heredity. Genes are specific sequences of bases that encode instructions on how to make proteins. Genes comprise only about 2% of the human genome; the remainder consists of non-coding regions, whose functions may include providing chromosomal structural integrity and regulating where, when, and in what quantity proteins are made. The human genome is estimated to contain 20,000-25,000 genes.

Although genes get a lot of attention, it’s the proteins that perform most life functions and even make up the majority of cellular structures. Proteins are large, complex molecules made up of smaller subunits called amino acids. Chemical properties that distinguish the 20 different amino acids cause the protein chains to fold up into specific three-dimensional structures that define their particular functions in the cell.

The constellation of all proteins in a cell is called its proteome. Unlike the relatively unchanging genome, the dynamic proteome changes from minute to minute in response to tens of thousands of intra- and extracellular environmental signals. A protein’s chemistry and behavior are specified by the gene sequence and by the number and identities of other proteins made in the same cell at the same time and with which it associates and reacts. Studies to explore protein structure and activities, known as proteomics, will be the focus of much research for decades to come and will help elucidate the molecular basis of health and disease.

“It’s hard to exaggerate the importance of this announcement,” says Dr. Michael Hayden, Director and Senior Scientist at the Centre for Molecular Medicine and a professor of medical genetics at the University of British Columbia. “This is going to be the heralding of medicine that is predictive and will allow us to understand more about the environment we live in.”

Though the direct benefits from this knowledge will be noticed further down the road, it’s tantalizing now to think about what it could make possible.

So what does this mean for the average person? “The immediate benefit is having a complete map of all the genes in a human being,” says Dr. Michael Smith, Nobel Laureate and Director of the BC Cancer Agency’s Genome Sequence Centre in Vancouver. “Until you knew all the bones in your skeleton, you’d never hope to understand how a human being fits together. So until you understand all the genes, you don’t have a listing of all the information that can be used to make a brain or a kidney or a liver. The big excitement now is really about the prospects for advancements that this new information will make possible.”

Essentially, the possible benefits from the announced information break down into four areas: the ability to perform genetic diagnostic tests, personalized drug manufacturing, gene therapy and highly controversial genetic engineering.

Diagnostic tests or genetic screening may be one of the first practical uses for this new information. A single drop of blood would be all that is necessary to screen for elements that may make a person susceptible to heart disease or certain kinds of cancer – widely believed to be influenced by genetic factors. With the more detailed tests the new genome information may soon make possible, high-risk patients could be identified earlier in time to make lifestyle changes that could prevent future illness.

Another exciting prospect is the introduction of tailor-made drugs that would be more effective for more patients and contain fewer side effects for each individual. More than two million people in the U.S. are hospitalized each year due to reactions to medication – more than 100,000 of those die. The new genome data could help identify groups of people more prone to reaction. Perhaps most important, the human genome data has the ability to help identify new targets on which drugs can act on disease for individuals. Even if a drug is just ineffective for a certain group, the cost savings benefit alone would be impressive.

Using genes themselves as medicine is the most direct way the new information may benefit you. Though it carries significant risks to patients, gene therapy could still be invaluable for fighting single-gene disorders, such as cystic fibrosis. In that case, the new information could be used to identify the abnormal cystic fibrosis gene and replace it with the healthy one that should be there.

Finally, the new genome information could make various forms of genetic engineering faster and easier. It could even make controversial techniques like germ-line engineering – the editing of DNA inheritance passed down from one generation to the next – more of a possibility. Such a technique would involve identifying an abnormal gene and then correcting that gene in eggs and sperm. Though this is by far the most debated of the uses for the human genome map, it would mean that no further generations would be affected by any genetic defects from their ancestors.

Despite the universe of ethical questions that some uses for the new genome information will undoubtedly raise, there is little doubt that the findings of human genome research efforts will soon begin to change our lives.

“We’re going to be able to look at biology on a much more molecular level,” says Smith. “We’ll be able to recognize much earlier when things aren’t working properly. It’s hard to say it’s going to cure cancer next year. That wouldn’t be true. But I think it will certainly accelerate progress that’s already taking place.”

]]> http://scienceniche.com/type/research/necessity-understanding-of-human-genome.html/feed 0 http://scienceniche.com/life-science/zoology/midnight-zoo-night-safari-at-singapore.html http://scienceniche.com/life-science/zoology/midnight-zoo-night-safari-at-singapore.html#comments Sun, 20 Jun 2010 15:08:10 +0000 admin http://scienceniche.com/?p=5341

It can be an annoying experience going to a zoo and waiting for minutes on end to see an animal that you’re told is just hiding. But maybe it’s hiding for a reason. It hasn’t got anything to do with shyness either. It’s a simple fact that a lot of animals are nocturnal, and by their very nature, they just don’t like to be out and about during the daytime. When most other animals are asleep under the cover of darkness, these other animals come alive, and unfortunately seeing what they get up to is a bit of a mystery. That is, until now.

Night Safari at the Singapore Zoo proudly calls itself “the first wildlife park built to be viewed at night.” Officially opened in 1994, the exhibit took four years to plan and three years to construct – which is not surprising given that it’s set in 40 hectares of fairly dense secondary forest. By using subtle lighting, visitors can view about 100 species that like to go about their business at night. In fact, there are over 1,000 nocturnal animals that call the Night Safari home, so it’s not exactly a small experiment.

The birth of the Night Safari is a result of a combination of factors. The overwhelming response to night tours conducted at the Zoo in the late 1980s indicated a demand for wholesome night entertainment. Displaying tropical animals at night seemed ideal since 90% of them are nocturnal and therefore most active after dusk. Singapore’s predictable sunset at around 7.30pm and cool nights with little rainfall mean fewer operational problems for an outdoor night attraction.

Like the adjacent daytime zoo, the larger Night Safari grounds employs an ‘open concept’ design, where by the use of moats (both wet and dry) and effective camouflage, animals can be seen in their respective areas appearing as if they are roaming freely in the wilderness – everything from such rarely seen creatures as the slow loris or the fishing cats.

The Night Safari itself is divided into eight geographical zones representing the wildlife of Asia, Africa and South America. What’s more, there are three walking trails that make it feel like you’re exploring the dense jungle on foot, even though you’re just a visitor to a very special zoo. After all, it really does feel like a legitimate jungle. That might have something to do with the over 20,000 plants and 900 forest trees that makes up the background for these jungle animals.

What makes the zoo work so well, as a night time only experience, is the careful placement of lighting. The lighting is sufficient to clearly see the animals moving about (after you eyes have acclimatized to the dimness), but not bright enough that they won’t venture from A to B. According to the zoo, the effect is slightly stronger than natural moonlight.

If you’re lucky enough to be heading to Singapore any time soon, be sure to check it out. And rule out the morning or afternoon options. The doors are only open to the public from 7:30pm to midnight.