Download Properties of the Major Biological Molecules

Properties of Important
Biological Molecules
Try your best to answer these questions:
Matter is the stuff that makes up everything in
our universe.
-Where did the matter that makes you come from?
-If you grow another inch this year, where does that matter come from?
Energy is the ability to do work.
-Where is your energy coming from?
-Is it possible to run out of energy?
Of course, the answer to all this regards the food we eat. Its something we
never think much about, but is clearly of crucial importance to any living
system. A clear understanding of the composition of food and how our
bodies manipulate it is essential to a basic knowledge of biology.
There are specific types of biomolecules (aka macromolecules) in our food
that are essential in building and maintaining living systems. These include
carbohydrates, lipids, proteins, and nucleic acids. (vitamins and minerals
are needed in much lower proportions). Although there are many examples
or each type of molecule, you will only research those that will be the most
relevant to the rest of this course.
This assignment will measure your ability to utilize informational resources,
and to instruct your classmates about what you have learned. You and a
partner will be assigned a specific molecule of crucial importance to all life.
You will then develop a multi-slide presentation that reviews this single
biologically important molecule. You may use any software of your choice.
Research and present information that fully explains the prompts I have
developed for each molecule. Consider that you may need to provide
additional information to thoroughly explain the questions I have asked of
you.
Your grade will be determined by a FIT evaluation and a summative quiz
that covers the work of all groups- so pay attention to others! Be aware that
your research will be helpful in your own understanding of the structure and
function of biomolecules, as well as the classmates you present to.
Fat:
 What is the biological term for fat?
Fats are also referred to as lipids, and also include phospholipids, cholesterol, and steroids.
 What does fat look like on a molecular level?
A molecule of fat generally consists of three fatty acid molecules covalently bonded to a
molecule of glycerol. Notice the high number of hydrogen/carbon bonds and the relatively
few number of oxygen atoms.
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 What are the many functions of fat in living organisms?
Fats are necessary to digest vitamins A,D,E, and K, they insulate our body against cold,
provide cushion for internal tissues, and provide long-term energy storage for future needs.
 In what foods would I find fat?
Vegetable oils, lard, butter, whole milk, peanuts, coconuts, avocados, all are high in fat.
 Why are some fats found in solid forms while others are liquids?
Animal fats tend to in solids while plant fats tend to be liquids. This is determined on a
molecular level by the amount of hydrogen within the fatty acids. If every carbon in bonded
to as many hydrogens as possible, the fat is considered saturated. If there is a gap left open in
the molecule where a hydrogen could have been, the fat is considered unsaturated. Saturated
fats can pack together densely to form solid, while unsaturated fats have kinks in the
molecule where the hydrogen is absent- this prevents them from densely packing together
and keeps this type of fat in liquid form.
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 What is the most common atom found in all fats?
Hydrogen is the most common element in all fats
 Give an example of a type of lipid that is important is determining sex
characteristics:
Fat is just one type of lipid. Another type of lipid is cholesterol, which is the precursor to
such sex-determining hormones as estrogen and testosterone.
Phospholipids:
 What makes a molecule polar or non-polar?
When electrons in covalent bonds are not equally shared, one atom tends to become a bit
more negative as it pulls electrons a bit more towards it. This makes a molecule polar since
one side of the molecule become a little more negative, while the other more positive. A
non-polar molecule is formed when the atoms in a covalent bond equally share electrons so
that no region within it has a charge.
 What is the most common polar substance on Earth?
Water is the most common polar substance on Earth
 What is the difference between a hydrophilic and hydrophobic substance?
A hydrophilic substance has its atoms arranged in a manner that make it attracted to water
molecules. Hydrophilic substances are polar (like water) and can dissolve in it. Hydrophobic
substances are repelled by water- they are non-polar and will not dissolve in it.
 Is a phospholipid considered polar? Hint: it’s “ambivalent”
A phospholipid is neither polar or non-polar. It is made of two parts referred to as the “head”
and the “tail”. The head is considered polar, while the tail is non-polar. Since half the
molecule is hydrophilic and half hydrophobic, phospholipids take on a peculiar property of
being ambivalent in water- they kinda’ do and don’t dissolve.
 What do phospholipids look like on a molecular level?
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 What happens when phospholipids are placed in water?
Due to their ambivalence, when placed in water they spontaneously arrange themselves into a
bi-layer (two layers) that forms a bubble. In the middle, all the tails sandwich togetherremember, they are hydrophobic and don’t want to touch the water. On the outside of this bilayer are the heads- remember, they are hydrophilic so they can dissolve in the water.
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 What parts of our body are made of phospholipids?
The cell membranes of all organisms are made from phospholipids.
Cellulose and Starch:
 How does a monomer differ from a polymer?
A monomer is a basic building block that can be linked together with other monomers to
form a chain. This chain is referred to as a polymer.
 How do dehydration reactions work to build polymers?
In dehydration reactions, monomers bind to each other to form polymers. This occurs when
an O and H from a monomer break off and attach to a H from another monomer to form H2O.
These monomers now have room to covalently bond to each other. This happens over and
over until a long chain of monomers forms a polymer.
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 In what foods would I find starch? How about cellulose?
Starch can be found in grains, potato, and pasta. Cellulose is found in plant material like
broccoli, lettuce, celery- it is commonly referred to as fiber.
 What do cellulose and starch have in common?
Both polymers are made from long chains of the monomer called glucose.
 How are their molecular structures different?
Starch is made of a long chain of glucose are bonded together at the same angle. Cellulose is
made from a slightly different form of glucose that bonds together at opposite angels.
 How are their functions different?
Starch is a storage molecule that organisms use to store glucose until it is needed in the
future. Cellulose is a building material that only plants use to construct their cell walls.
 Why is cellulose so hard for animals to digest?
The enzymes animals have to break starch into glucose monomers does not work on the way
glucose is bonded together in cellulose.
 What does starch look like on a molecular level? How about cellulose?
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Glucose:
 What does glucose look like on a molecular level?
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 What is the atomic composition of glucose?
Glucose is made of 6 carbon atoms, 12 hydrogens, and 6 oxygens.
 In what foods would I find glucose?
Many foods have glucose or some form of similar sugar. These include fruits, milk, juices,
candies, and anything with table sugar.
 Where does the glucose in all food originally come from?
All glucose originally comes from plants through the process of photosynthesis.
 Why is glucose considered a simple sugar? Give other examples of simple sugars.
Glucose is considered a simple sugar since it is made of just one monomer. Other simple
sugars are made of two monomers covalently bonded together. Examples of simple sugars
made from just one monomer (called monosaccharides) are fructose and galactose.
Examples of simple sugars made from two monomers (called disaccharides) are lactose and
sucrose (table sugar).
 What is a complex sugar? Give other examples of complex sugars.
A complex sugar is a long chain of simple sugars that are bonded together through
dehydration reactions. Examples include starch and cellulose
 Based on its function, why is glucose considered a ubiquitous food in biology?
Glucose is the primary molecule that every cell uses to fuel its function. Glucose provides
the immediate energy needed for all organisms to recharge their “batteries”.
 What does glucose have to do with diabetes?
Diabetes is a condition that occurs when animals can’t regulate the amount of glucose in their
bloodstream.
ATP
 What is the function of ATP?
Adenosine TriPhosphate is a molecule that stores the energy in food for future use.
 Where does our body get ATP? Can we directly eat it?
Although we can’t directly eat ATP, the energy in any food molecule can be used to charge
molecules of ATP. Glucose is the easiest molecule to use when charging up ATP.
 Why is ATP often compared to a battery?
Just like a battery, ATP can use another energy source to become charged. It can then store
that energy for future use. ATP also has the ability to be repeatedly recharged.
 How does ATP actually store energy?
ATP is the charged version of another molecule called ADP. The ADP molecule has 2
negatively charged phosphates on its end- these phosphates don’t like being next to each
other. To put another negatively charged phosphate onto these two would take a lot of
energy- and that’s exactly what happens. The energy in our food is used to force another
phosphate onto ADP to make ATP. The forced phosphate has much stored energy in it.
When we later need this energy, ATP converts back to ADP by releasing a phosphate and its
stored energy.
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 What does ATP look like on a molecular level?
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 What is the relationship between ATP and ADP?
ADP is an uncharged version of ATP- food energy is stored as ATP when converted from
ADP.
 How much ATP can I get from eating a single molecule of glucose?
If there is plenty of oxygen around, a single glucose molecule can charge 38 ATPs.
 How much ATP does my body use every single second?
Every second, each of your over 100 trillion cells uses up to 10 million ATP molecules.
Proteins:
 What smaller molecules are used to build all proteins?
The monomers that are used to build polymers like protein are called amino acids.
 In what foods would I find protein?
Meat, dairy, nuts, and legumes are all high in protein.
 What are some examples of important structural proteins that humans use?
Structural proteins are those that help build parts of us. Keratin is used to build our hair and
nails. Collagen is important in building our bones. Actin and myosin are the proteins that
build our muscles.
 What does protein look like on a molecular level?
Each dot in the image below represents a single amino acid:
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 What makes one protein different from any other type of protein?
Each protein can be made from up to 20 different amino acids that are bonded to each other
in one long chain. Protein polymers can be made of a chain of over 15,000 amino acids. The
ordering of these amino acids is variable from one protein to the next. The specific ordering
of these amino acids ultimately affects the exact 3-dimensional structure (shape) of the
protein. So, ultimately any two proteins are different from one another due to the shape they
form from the sequence of their amino acid monomers.
 What is the difference between a polypeptide and a protein?
A polypeptide is a short, straight chain of amino acids. A protein is a very long polymer that
has been bent and folded into a very specific 3D shape.
 What is an enzyme?
An enzyme is a protein that acts as a catalyst to speed up the rate of a reaction. Most
reactions in living things would happen too slowly without the aid of enzymes.
 What happens to a molecule of protein when you denature it?
When a protein is put into a unique environment (high heat for example), it loses its 3D
shape. Since this shape is what makes a protein unique and determines its function, the
protein will no longer work correctly if it is denatured. In your potato lab, the enzyme in the
potato (catalase) was denatured by heat, so it no longer reacted with the hydrogen peroxide.