Macromolecules Worksheet Template

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Macromolecules Concept Questions
1. Explain the relationship between monomers and polymers, using polysaccharides as an example.
(Polymers are large molecules made up of a chain of smaller molecules called monomers. Monosaccharides
are joined together to form polysaccharides.)
2. a) Plants make a huge amount of cellulose each year which could be an excellent source of glucose as food
(The β14 links between glucose molecules can=t be
for humans and other organisms. Why is it not?
hydrolyzed by our enzymes.)
b) Although it can=t be digested, why is fibre (i.e., cellulose) considered to be an important part of a healthy
diet? (Fiber is not digestible so it fills the colon faster making more frequent bowel movements. This
removes toxins and possible carcinogenic compounds from the colon.)
c) Wait a second, grass is the major part of the diet of herbivores like cows. How can they digest it?
(In
the gut of cows and other herbivores there are microbes that are able to digest cellulose because they contain
enzymes that can metabolize β14)
3. Lipids and carbohydrates can both be used as energy by cells. If you need quick energy, which might you
choose to eat?
(Carbohydrates are metabolized more quickly than lipids.)
4. Which of these things is not like the others?
a) fiber
(b) sugar
(c) starch
(d) cellulose
(e) fat
(Fat is not like the others
because it is not a carbohydrate.)
5. How does the structure of an unsaturated fatty acid differ from the structure of a saturated fatty acid? Give
an example of a food that contains each.
(Unsaturated fats contain double bonds. Animals (except for
some fish fats) produce saturated fats. Plants produce unsaturated fats.)
6. Explain why some fatty acids are solid at room temperature while others are liquid. (Saturated fatty acids
are relatively straight so they pack closely together and are solid at room temperature. The double bonds of
unsaturated fats cause kinks so they don=t pack as closely and are liquid at room temperature.)
7. When you consume more food than you need for energy, the excess can be stored in the form of lipids.
Why are lipids particularly useful for this purpose? (Lipids store more than twice the energy of
carbohydrates.)
8. a) What property do all lipids share?
(All lipids are hydrophobic.)
b) How does this make them ideal for building cell membranes? (The amphipathic nature makes them form
a bilayer.)
9. What effect does hydrogenation have on fatty acids? (Hydrogenation converts an unsaturated fat to
saturated by adding hydrogen to the double bonds. This makes the fat more solid.)
10. a) Cholesterol usually gets a bad rap in the media. What makes it a health risk?
(Cholesterol is
nonpolar so tends to accumulate on arterial walls, making them narrower and increasing blood pressure. This
also increases the risk of stroke and heart attack.)
b) Should we try to eliminate it from our diet?
(Our cells are able to manufacture all the cholesterol
they need so any dietary cholesterol is excess.)
c) Do we need cholesterol?
(Cholesterol is a necessary component in cell membranes and is used to
produce some hormones.)
11. a) Why is a protein called a polypeptide? (A protein consists of many amino acids joined by peptide
bonds.)
b) Why is a polypeptide not a protein?
(To be a functional protein, a polypeptide has to be folded into a
specific shape.)
12. Why are some amino acids soluble in water while others are not? (An amino acid with a polar R group
would be polar and hydrophilic. One with a non-polar R group would be non-polar and hydrophobic.)
13. Although some people are vegetarians and therefore not eating meat, why do they need to make sure to
include meat alternates in their diet?
(Humans cannot synthesize all amino acids and so we must get
them in our diet. In order to get all amino acids and sufficient protein, one must eat a variety of plant
products and meat alternatives.)
14. Explain how the 3-dimensional shape of proteins is formed. (Interactions between the R groups of
amino acids hold the polypeptide in its correct shape.)

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