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Showing posts with label enzymes. Show all posts
MONDAY, MARCH 5, 2012
Easy Enzyme Experiment: Potato Catalase
Catalase enzyme formed the bubbles in the two tubes on the right. The tubes contain extracts from beef muscle, kidney, and
liver from left to right.
In a post awhile back we discussed the enzyme catalase and its presence in animal
tissues such as liver, kidney, and muscle. Catalase was and is found to be extremely
abundant in the liver, a reflection of the livers cleansing function. It is also present, but
much less so, in the kidneys, also a reflection cleansing function. Muscle tissue however
had no detectable catalase due to the fact that it is not a cleansing organ, waste products
from the muscles are rather filtered and cleaned by the liver and kidneys. Catalase also
has been found in plants, where its presence is often mysterious. Plants of course are
not producing waste products similar to what animals produce, so why would they need
catalase? We can discover the answer partially by simply understanding the function of
catalase.
This is what catalase does in general:
Hydrogen Peroxide + Catalase → Water and Oxygen
Hydrogen peroxide is a highly oxidative molecule, meaning it causes processes similar to
rusting to occur. Metals rust as they react with oxygen and oxidative molecules cause
rusting to occur. Similar “rusting” or oxidative reactions can occur in plant or animal
tissues if oxidative molecules are present. This is why anti-oxidants are such a big deal,
they prevent tissue from oxidizing by getting rid of oxidizing molecules such as hydrogen
peroxide. Catalase is such an anti-oxidant molecule. Catalase also converts reactive
oxygen, which also oxidizes, into hydrogen peroxide and then into harmless water and
oxygen. (Of course I have simplified these reactions, so chemists, refrain from
complaint!) At the end of a reaction catalase is preserved and available to repeat the
reaction over again with more oxidative molecules. Amazingly, one catalase enzyme
can repeat these reaction up to 40 million times in one second!
Another catalase reaction:
Reactive Oxygen + Catalase → Hydrogen Peroxide + Catalase → Water and
Oxygen
In animals, such as us, oxidative molecules are most often produced through our
metabolizing of food molecules. So the presence of catalase makes sense. Plants do
not eat, so why would they need catalase? If we study the process of photosynthesis we
may come across a term called photorespiration. Photorespiration simply is when a
plant receives too much light and not enough water. As a result, the plant can produce
large amounts of hydrogen peroxide which can kill the plant. Fortunatly, catalase
prevents the accumulation of hydrogen peroxide by converting it to water and oxygen,
and so saves the plant from oxidative damage.
A Simple Catalase Experiment Using Potatoes:
Some plants such as potato and spinach have very high levels of catalase, far higher
they they would likely ever need to prevent photorespiration damage. Why that is, no
one seems to know. Scientists have had many ideas and have researched the question
for almost 100 years but no one can figure it out. But it makes isolating the catalase
enzyme very inexpensive and easy if you want to run a simple experiment. The following
is a simple enzyme experiment anyone can run.
Materials:
Potato
Test tube or other small container
Hydrogen Peroxide
1. Cut up a potato and mash it. Do not cook it, cooking will break down the enzyme so it
won’t work.
2. Place the mashed potato in a test tube or other small container.
3. Add hydrogen peroxide. If there is catalase present foam should be produced.
The foam produced is a result of catalase converting hydrogen peroxide into water and
oxygen, the bubbles are filled with this oxygen. The more bubbles produced the faster
catalase is carrying out this reaction, or the more catalase present. The above would be
considered the control for the experiment and simply indicated the presence of catalase
in the potato. Tests can be preformed to determine the effects of different conditions on
the enzyme function. By adding baking soda to the potato, a high pH or basic molecule,
will change the pH and have an effect on how well catalase functions. To another test
tube, add vinegar to the potato which will lower the pH, making it acidic also having an
effect. Also try freezing or cooking the potato before adding hydrogen peroxide to
determine effects. Remember, the more foam produced the better the catalase enzyme
is working. Less foam means it is not working as well, and no foam means it is not
working at all. Test it out and see what you find.
Potato catalase experiment. The boiled tube (left) produced no bubbles indicating catalase has been degraded by the
heat. Room temperature tube (middle) produced the most bubbles indicating catalase is highly functional at this
temperature. The tube kept on ice (right) produced fewer bubbles indicating the lower temperature slowed down the catalase
enzyme.
Posted by Matt at Monday, March 05, 2012 7 comments:
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Labels: enzymes, experiments, Plants
MONDAY, JANUARY 9, 2012
Easy Enzyme Experiment: Protease and Gelatin
In the two beakers of gelatin above, fresh pineapple was added to the one on the left and canned pineapple to the one on the
right. The enzyme protease, present in the fresh pineapple on the left, broke down the structure of the
gelatin liquefying it. The canning process breaks down the protease enzyme so it no longer works so the beaker on the right
has solidified gelatin in it
Being that enzymes breakdown molecules or digest them, enzymes are extremely
important to our own food digestion. Every living organism has enzymes within their
body in order to do molecular work and we are no exception. Plants and animals alike
have enzymes, and interestingly they often have similar enzymes. When animals eat
protein, in order for them to breakdown the protein so it can be absorbed by the body it
must be digested into amino acids. Amino acids are the individual molecules that when
strung together make proteins. The group of enzymes called proteases are responsible
for the breakdown and digestion of protein in the body. Some plants, such as pineapple
also have high levels of protease enzyme. Specifically, pineapple has a protease called
bromelain. Pineapple bromelain has been utilized for all kinds of medical purposes some
of which work and others of which do not. At least to some degree, it does aid the
digestion of proteins if we consume it with meat. Bromelain also is commonly used as a
meat tenderizer, in effect, it is digesting the meat before we eat it. I have done quite a bit
of reading on the internet as to why pineapple would need bromelain in it, but couldn’t
come up with anything. The only thing I can think of is that protease would probably help
pineapple fight off infectious organisms. By using fresh pineapple we can carry out a
very simple enzyme experiment demonstrating the action of protease.
As mentioned before, protease digests protein helping to tenderize meat. This is helpful
in some circumstances but not in others. For example, if you make Jello or any other
type of gelatin food, adding pineapple will ruin the dish. Gelatin makes a liquid into a
solid by the action of a protein called collagen. This is the most abundant protein in
humans, composing as much as 25 to 35 percent of all our bodies protein. It is utilized in
connecting and holding things together in the body. It is also abundant in other animals
of course, and almost all collagen protein for gelatin is extracted from pork and beef skin
and bone after the butchering process. Contrary to popular belief, animal hooves are
typically not used. On the side of the Jello box it says to not add raw ginger, pineapple,
kiwi, or papaya. All of these foods naturally contain protease enzymes that would digest
collagen and prevent the gelatin from solidifying.
A basic experiment can demonstrate this:
Materials:
Fresh pineapple
Jello or gelatin and supplies for making it
1. Make your gelatin as directed on box.
2. Pour liquid gelatin into multiple containers for different treatments. For example: 1
container as a control where nothing will be added, a second container where chunks of
fresh pineapple will be added, and a third or more where other test items might be
added. Other test items might be canned pineapple, the other fruits mentioned above, or
anything else you want to test.
3. Add the fruit to the different containers and let the gelatin solidify.
After the gelatin is supposed to solidify you should find that the gelatin container where
nothing was added has solidified. The container where fresh pineapple was added
should still be liquid. The liquid indicates that protease from the pineapple digested the
collagen protein preventing the gelatin from solidifying. If you add canned pineapple to
another container the gelatin should solidify. This is because heating in the canning
process breaks down, or denatures, the protease enzyme in pineapple. Try other fruits
and see what happens or see if cooking fresh pineapple has the same results as canned
pineapple.
Posted by Matt at Monday, January 09, 2012 No comments:
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Labels: enzymes, experiments, Lab activities
MONDAY, JANUARY 2, 2012
What Your Body Does to Alcohol: Alcohol Dehydrogenase
The enzyme alcohol dehydrogenase (ADH) is found only in the liver and converts alcohol (ethanol) into acetaldehyde, then
acetaldehyde dehydrogenase (ALDH) converts acetaldehyde into acetic acid (commonly known as vinegar) which is
harmless to the body.
Some of you may have had a few drinks on new years eve... And some may be wondering what
happens to alcohol once it enters your body. And how does your body get rid of that alcohol once
it enters your system? To be sure, alcohol is a toxin which amazingly most peoples bodies are
relatively adapted to. Though still, your body must get rid of the alcohol within your body,
otherwise it might kill you.
With any alcoholic drink, the alcohol is rapidly absorbs into the blood stream through
the stomach and small intestine. Once in the blood, alcohol rapidly travels through out the
body. The most notable and immediate effects on the body take place in the central nervous
system, the brain and spinal cord. These organs are depressed, or slowed down, by alcohol and
cause the rest of the body to also slow down. This results in confusion and lack of
coordination. If these and other organs are exposed to too much alcohol for too long the alcohol
will kill the cells. The cells of the liver are the only cells in the body with any defense against
alcohol poisoning. Liver cells produce the enzyme alcohol dehydrogenase which converts alcohol
into acetaldehyde. Acetaldehyde is then converted into acetic acid, more commonly known as
vinegar, which is harmless to the body. The body then can excrete the acetic acid out through
urine. The liver process about one half ounce of alcohol per hour, and drinking more alcohol
faster then your liver can process it will result in inebriation, alcohol poisoning, and in large
amounts even death. The liver thus processes alcohol out of the blood for the entire body. Again,
alcohol is a poison to which your body is adapted to in small amounts, large amounts will kill you
simply because the liver can't keep up. Without the activity of alcohol dehydrogenase in your
liver though, even small amounts of alcohol could kill a person.
Some people have livers that produce more alcohol dehydrogenase when compared to
others. People that produce more alcohol dehydrogenase in their livers are able to process more
alcohol and therefore not get drunk as easily. Some people produce extremely low levels of
alcohol dehydrogenase and therefore are extremely susceptible to drunkenness and
alcoholism. Some ethic groups genetically do not produce much alcohol dehydrogenase and are
therefore very prone to alcoholism. Interestingly, several types of mushrooms from the genus
Coprinopsis contain a chemical called coprine, which inhibits the livers ability to process
alcohol. Inky cap mushrooms are the most common species consumed within this
genus. Coprine inhibits acetaldehyde dehydrogenase and without this enzyme functioning,
acetaldehyde can accumulate to toxic levels.
So hopefully you didn't test your livers ability to produce alcohol dehydrogenase too much this
new years. And hopefully you are one to setting some good new years resolutions. In my next
post I will be discussing one of my resolutions. And happy new years to you!
Posted by Matt at Monday, January 02, 2012 No comments:
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Labels: cells, enzymes, Health, seasons
MONDAY, DECEMBER 26, 2011
Easy Enzyme Experiment: Rennet and Cheese Making
Curds separating from whey after being mixed with rennet.
Learning about cheese can be an amazingly diverse education in history, culture, as well
as science. Cheese making beautifully integrates both art and science, one without the
other will result in a mediocre cheese at best. Of course milk of all types is the primary
ingredient in making cheese. Along with milk though many combinations of bacteria,
enzymes, aging processes, moisture, humidity, and other factors are controlled in the
cheese making process. Most cheeses found in the supermarket utilize a specific
enzyme (or rather a complex of enzymes) called rennet. Typically, rennet is one of the
first things added to milk in the cheese making process. Once added, it immediately
starts separating curds and whey. Rennet acts on the milk protein casein by making it
non-soluble. Milk is normally white because casein protein is dissolved and floating
around in it. However, when casein is made insoluble through the action of acids or
enzymes like rennet, it precipitates out forming white clumps called curds. For a few of
the most basic cheeses only rennet is utilized. Most cheeses found in the supermarket
however utilize a combination of bacteria and rennet. For this cheese making
experiment we will only use rennet in order to display its function.
As with the history of yogurt, the history of rennet goes back many thousands of years. And
similar to how most great discoveries are made, rennet was likely discovered by
accident. Presumably, we can imagine, thousands of years ago some dairy worker ran out of
milk containers. The dairy worker also had probably just butchered a young animal and
found a left over stomach. Thinking the stomach would make a good milk container, filled
it up and let it sit. When the worker came back at a later time he would have been surprised
to find the milk was now separated into curds and whey but not rotten smelling. Then by
draining off the whey the curds would have made the first cheese. This would have been the
first known accidental use of rennet.
Being rennet begins the process of digesting milk it makes perfect sense that it would be
found in the stomach of a young animal from the dairy herd. This is in-fact where most
rennet historically has come from. Today however, rennet is often created by bacteria in a
laboratory or derived from plant based products. Various plants, for example stinging
nettle, have enzymes in them that have effects on milk similar to rennet. From what I have
heard, animal based rennet works best. But each cheese maker has their preferred and even
secret type of rennet, and boy can they be opinionated! I personally have used Junket
rennet tablets with what I consider good results. Junket and other rennets can be found and
purchased on Amazon and occasionally in the supermarket.
How to make rennet cheese:
Materials: Spoon, stainless steel pot, thermometer, and strainer
Ingredients: Milk, water, salt and rennet
1. Heat the milk to 180 degrees Fahrenheit. This pasteurizes the milk so no bacteria cause it
to spoil. Slowly heat milk and stir gently every once in a while to ensure milk does not burn.
2. Depending on the directions on the type of rennet you purchase, mix up the
rennet. For Junket dissolve your tablet in ¼ cup of cool water. I prefer to mix ½ tablet
with ¼ cup water.
3. Let milk cool to about 100 degrees Fahrenheit. Add the rennet solution and mix by st
iring for about 1 minute.
4. Let milk/rennet mixture sit as close to 100 degrees as possible overnight. Let the mixture sit
absolutely still, do not disturb!
5. The next day the curds should be separating from the whey. Simply dump these through a
strainer to separate. The curds left in the strainer is the cheese. Transfer the curds to another
container and salt to taste.
Curds after straining and salting.
The body temperature of a cow is about 100 degrees, so it makes sense that rennet would work
best at this temperature. At cooler temperatures rennet either will not work or will work very
slowly. Warmer temperatures will break down, or denature, the enzyme so it won’t work at all.
After the curds and whey are separated the resulting cheese will be very soft and will taste like
milk. Unfortunately, at least for this cheese, most taste is derived through bacterial
metabolism. What this basic rennet cheese is known for though is adding things into it. It is often
used as a cheese for making spicy dips also when mixed with chili peppers. Other fruits, veggies,
and herbs can also be mixed with it and it can be used as a cream cheese. You can experiment and
come up with your own recipe.
Posted by Matt at Monday, December 26, 2011 No comments:
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Labels: cheese, enzymes, experiments, Lab activities
TUESDAY, APRIL 12, 2011
Cellular biology game: CellCraft
I accidentally happened across a free on-line game called CellCraft. Supposedly some sort of off
take of the game World of Warcraft, except with a cellular biological twist.
CellCraft: Build a cell, fight off viruses, survive harsh worlds, and save the Platypus
species!
Fairly interesting, possibly slightly addictive to biologists, pretty informative with quite a few
interesting and important concepts taught through the game, and kind of weird. A good
educational game to check out at least.
Check it out here: CellCraft or CellCraft Home
If anyone plays this game I would sure be interested in what you thought of it. So let me know!!!
Posted by Matt at Tuesday, April 12, 2011 No comments:
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Labels: cells, enzymes
WEDNESDAY, MARCH 9, 2011
Amylase and a simple enzyme experiment
When it comes to digestion, chewing is the obvious starting point. Less obvious however are all
the enzymes contained within our saliva that also aid digestion. Enzymes simply put are
chemicals that aid the breakdown of substances, or cause a certain chemical reaction to take
place. In the case of saliva, a particular enzyme called Amylase aids the break down or digestion
of carbohydrates and starch, turning them into sugars. Part of the function of chewing is not only
to break our food into smaller pieces but also to mix food thoroughly with amylase so our food is
digested more efficiently. We may have consciously experienced the effects of amylase when
eating starchy or carbohydrate rich food and notice that the food becomes slightly sweeter after
chewing a while. This sweet taste is a result of amylase breaking down carbohydrates or starch
into sweeter tasting sugars.
We developed a simple lab experiment demonstrating the effects of amylase that anyone can do
with some basic equipment. This is probably an experiment that others have developed, I just
haven't come across it before. All that is needed is a test tube, chlorine free water, saltine
crackers, potassium iodide, and spit. Tap water can be de-chlorinated by letting it set out for 24
hours and potassium iodide(IKI) and test tubes can be purchased on-line.
Here are the steps to this experiment:
1. Crush up part of a saltine cracker into a fine powder. You don't need much, only enough to
cover the bottom of a test tube. (this imitates the effects of chewing)
2. Place the crushed cracker in the bottom of a test tube, you only need enough to cover the
bottom.
3. Add an equal amount of de-chlorinated water to the test tube and mix thoroughly.
4. Add one or two drops of potassium iodide (IKI) to the water-cracker mix and mix again
thoroughly. At this point much of the cracker should turn a brown color. This is a result of the
IKI staining starches in the cracker brown.
5. Double (or slightly more) the total volume in the test tube with saliva. Yes, just let some spit
accumulate in your mouth and then spit into the test tube.
6. Mix and wait to see what happens.
Cracker ground up into fine powder. A small amount like this works best. Too much cracker makes the experiment work a
lot slower.
Cracker with de-chlorinated water added.
Cracker and water with an added drop of potassium iodide (IKI). Notice the darker appearance which is the result of IKI
staining starch brown.
Saliva added to the above mixture and let sit for about five minutes. The amylase in the saliva breaks down the starch into
sugar. When the starch disappears the IKI no longer stays brown but instead clears up. The lighter color indicates the starch
has been digested by amylase in the saliva. By waiting even longer the solution would clear up even more as more starch is
digested into sugar.
In the above experiment, as amylase within the saliva breaks down starch into sugar the brown
color disappears. This experiment can be modified to see if heated or cooled saliva will still make
the starch disappear. Chemicals such as vinegar or baking soda could be added, or other foods
tested out.
Posted by Matt at Wednesday, March 09, 2011 3 comments:
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Labels: enzymes, experiments, Lab activities
THURSDAY, OCTOBER 14, 2010
Gross and easy enzymes: Hydrogen Peroxide and Catalase
Enzyme experiments are often limited to molecular labs with expensive and sophisticated
equipment. There are however several enzymes that can be isolated very easily with minimal
equipment and materials. Catalase is one such enzyme that anyone can access for
experimentation. The process for isolating catalase, though easy, is like so many other cool
biological experiments: its kind of gross. But first, what exactly is an enzyme? An enzyme is a
protein that carries out a chemical reaction that normally would not take place. Our bodies, along
with all other organisms, are loaded with hundreds of different enzymes that control when, where,
and what chemical reactions happen. Specific types of enzymes only carry out one type of
chemical reaction but can carry out that reaction hundreds of times over. Enzymes are essentially
what do the 'work' of breaking down or digesting things such as our food and then building food
molecules into cells to form our bodies. The reaction that catalase carries out is converting the
potentially harmful hydrogen peroxide molecule into harmless oxygen and water molecules. This
is essentially what happens:
Catalase enzyme + hydrogen peroxide --> catalase enzyme + water + oxygen
After the catalase breaks down hydrogen peroxide into water and oxygen, catalase is then
available to carry out the same reaction again.
Samples of heart, kidney, and liver blended organs for catalase experiment.
The sediments at the bottom are tiny chunks that settled out.
In order for us to isolate catalase we must first locate some fresh liver. We get all of our liver,
or any other organ meats, from the local grocery store. We then take about five to ten grams
of liver (slightly smaller than a ping pong-ball) and place it in a blender with 500 ml of
distilled or unchlorinated water then blend until homogeneous. Once you have a
homogeneous mixture of liver juice, or any other juice for that matter, place several drops in a
test tube. Next, add several drops of hydrogen peroxide to your liver juice test tube. If
catalase is present in your liver juice, and it should be, foaming should take place. The foam
bubbles are full of oxygen that the catalase is producing by breaking down the hydrogen
peroxide. So the more foam that is produced the more catalase is present. You can repeat this
experiment with kidney juice, or any other type of meat.
In the picture at right I tested heart, kidney, and liver juice
for catalase by mixing them with hydrogen peroxide. From left to right we see the results for
heart (no foaming), kidney (foaming), and liver (slightly more foaming than kidney). Based
on these results we know that heart tissues have no catalase, kidney has catalase, and liver has
the most catalase. So why would heart have no catalase while kidney and liver have a lot of
catalase? Well the liver and kidneys are filtering and cleaning organs so having catalase
present in them would aid the cleaning of blood of harmful hydrogen peroxide
molecules. Heart on the other hand is not a cleaning organ so no catalase is present. Other
organs and tissues can also be tested in this way but the liver and kidney are the only ones we
have found that contain catalase. We have also tested plants but have only found spinach to
contain catalase for some strange reason. Why the heck would spinach have catalase? If
anyone can figure that out be sure to let me know.
Enzymes being large complicated proteins are very sensitive to temperature and pH. You can
do more experiments on catalase by heating or cooling the liver juice to see what effects
temperature has on foaming. Try putting it on ice or boiling it. Also, try adding a little
baking soda mixed with the juice to see how the enzyme works in a basic pH solution or
vinegar for a acidic pH solution. Nearly everything you need to know about basic enzyme
function can be accomplished through these simple experiments. There are a few other
enzymes that are also easy to handle in a non-lab environment that I will try to post at future
dates.
Posted by Matt at Thursday, October 14, 2010 No comments:
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Labels: enzymes, experiments, Lab activities
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