If a cell were to use only 10 of the 20 possible amino acids, how much effect would you expect this to have on protein diversity? Calculate and compare the number of different sequences that can be generated by randomly assembling either 10 or 20 amino acids into peptides that are five residues long.

What two functional groups are bound to the central carbon of every free amino acid monomer?

a. An R-group and a hydroxyl group

b. An N—H group and a (C═O) group

c. An amino group and a hydroxyl group

d. An amino group and a carboxyl group

What type of bond is directly involved in the formation of an α-helix?

a. Peptide bonds between amino acid residues

b. Hydrogen bonds between amino acid residues

c. Van der Waals interactions between nonpolar residues

d. Disulfide bonds between cysteine residues

What type of information is used to direct different polypeptides to fold into different shapes?

The structural level of a protein least affected by a disruption in hydrogen bonding is the

a. Primary level.

b. Secondary level.

c. Tertiary level.

d. Quaternary level.

Explain how molecular chaperones facilitate protein folding in many different polypeptides, each with their own specific shape.

Different proteins are composed of different sequences of ________.

a. Sugars

b. Lipids

c. Fats

d. Amino acids

e. Carbohydrates

Why are proteins not considered to be a good candidate for the first living molecule?

a. Their catalytic capability is not sufficient for most biological reactions.

b. Their amino acid monomers were not likely present in the prebiotic soup.

c. They cannot serve as a template for replication.

d. They could not have polymerized from amino acid monomers under early Earth conditions.

Predict the effect on protein function if each polypeptide adopted only a single, inflexible shape based on its primary structure.