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- Complete the following table to help you review the structures and functions of the four classes of organic molecules.
Problem 1
Problem 2
A glucose molecule is to starch as (Explain your answer.)
a. A steroid is to a lipid
b. A protein is to an amino acid
c. A nucleic acid is to a polypeptide
d. A nucleotide is to a nucleic acid
Problem 3
What makes a fatty acid an acid?
a. It does not dissolve in water.
b. It is capable of bonding with other molecules to form a fat.
c. It has a carboxyl group that can donate an H+ to a solution.
d. It contains only two oxygen atoms.
Problem 4
Cows can derive nutrients from cellulose because
a. They produce enzymes that recognize the shape of the glucose-glucose bonds and hydrolyze them.
b. They re-chew their cud to break down cellulose fibers.
c. Their digestive tract contains microorganisms that can hydrolyze the bonds of cellulose.
d. They convert cellulose to starch and can digest starch.
Problem 5
Of the following functional groups, which is/are polar, tending to make organic compounds hydrophilic?
a. Carbonyl
b. Amino
c. Hydroxyl
d. All of the above
Problem 6
Unsaturated fats
a. Have double bonds in their fatty acid chains
b. Have fewer fatty acid molecules per fat molecule
c. Are associated with greater health risks than are saturated fats
d. Are more common in animals than in plants
Problem 7
A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture
a. DNA
b. Proteins
c. Cellulose
d. Sucrose.
Problem 8
Which of the following substances is a major component of the cell membrane of a fungus?
a. Cellulose
b. Chitin
c. Cholesterol
d. Phospholipids
Problem 9
Which structural level of a protein would be least affected by a disruption in hydrogen bonding?
a. Primary structure
b. Secondary structure
c. Tertiary structure
d. Quaternary structure
Problem 10
Circle and name the functional groups in this organic molecule. What type of compound is this?
For which class of macromolecules is it a monomer?
- Most proteins are soluble in the aqueous environment of a cell. Knowing that, where in the overall three-dimensional shape of a protein would you expect to find amino acids with hydrophobic R groups?
Problem 11
Problem 12
Sucrose is broken down in your intestine to the monosaccharides glucose and fructose, which are then absorbed into your blood. What is the name of this type of reaction?
Using this diagram of sucrose, show how this would occur.
- Explain the role of complementary base pairing in the functions of nucleic acids.
Problem 13
Problem 14
What are the two types of secondary structures found in polypeptides, and what maintains them?
What stabilizes the tertiary structure of a polypeptide?
Problem 15
The diversity of life is staggering. Yet the molecular logic of life is simple and elegant: small molecules common to all organisms are ordered into unique macromolecules. Explain why carbon is central to this diversity of organic molecules.
How do carbon skeletons, chemical groups, monomers, and polymers relate to this molecular logic of life?
Problem 16
How can a cell make many different kinds of proteins out of only 20 amino acids?
Of the myriad possibilities, how does the cell 'know' which proteins to make?
Problem 17
Given that the function of egg yolk is to nourish and support the developing chick, explain why egg yolks are so high in fat, protein, and cholesterol.
Problem 18a
Enzymes usually function best at an optimal pH and temperature. The following graph shows the effectiveness of two enzymes at various temperatures.
At which temperature does enzyme A perform best?
At which temperature does Enzyme B?
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Problem 18b
Enzymes usually function best at an optimal pH and temperature. The following graph shows the effectiveness of two enzymes at various temperatures. One of these enzymes is found in humans and the other in thermophilic (heat-loving) bacteria.
Which enzyme would you predict comes from which organism?
Problem 18c
Enzymes usually function best at an optimal pH and temperature. The following graph shows the effectiveness of two enzymes at various temperatures.
From what you know about enzyme structure, explain why the rate of the reaction catalyzed by enzyme A slows down at temperatures above 40°C (140°F).
- Another aspect of the Nurses' Health Study looked at the percentage of change in the risk of coronary heart disease associated with substituting one dietary component for another. These results estimated that replacement of 5% of energy from saturated fat in the diet with unsaturated fats would reduce the risk of heart disease by 42%, and that the replacement of 2% of energy from trans fat with unsaturated fats would reduce the risk by 53%. Explain what these numbers mean.
Problem 19