Question 1

Which of the following best describes the effect of substituting a single amino acid in the primary structure of a protein?

Accepted Answer

It can cause a change in the protein's shape and function, depending on the properties of the substituted amino acid.

Question 2

Given the following two polypeptide chains: Protein 1: G-L-Y-T-R-Q and Protein 2: D-R-V-T-G-L, which statement is correct regarding their shape and function?

Accepted Answer

They may have different shape and function due to differences in their amino acid sequence.

Question 3

If a hydrophobic amino acid is replaced by a hydrophilic amino acid in a protein, what is the most likely consequence?

Accepted Answer

The protein's folding and function may be altered due to changes in interactions with water.

Question 4

Which amino acid substitution is most likely to cause a drastic change in protein shape/function?

Accepted Answer

Substituting Glu for Val

Question 5

A mutation causes the substitution of valine for glutamic acid in the hemoglobin protein. Which disease is most closely associated with this mutation?

Accepted Answer

Sickle cell anemia

Question 6

Which of the following equations represents the primary structure of a protein?

Accepted Answer

$$\mathrm{Primary\ structure} = \mathrm{Sequence\ of\ amino\ acids}$$

Question 7

Which amino acid substitution is least likely to alter the protein shape/function if substituted with an Arg residue?

Accepted Answer

Lys

Question 8

True or False: Changing the order of amino acids in a protein can change its shape and function.

Accepted Answer

True

Question 9

Which of the following best explains why a single amino acid substitution can have a significant effect on protein function?

Accepted Answer

Amino acids have different side chains that affect protein folding and interactions.

Question 10

A protein has the sequence: Ala-Gly-Val-Leu. If Val is replaced by Glu, what is the most likely effect?

Accepted Answer

The protein will gain a negative charge at that position, possibly altering its folding.

Question 11

Which of the following is an example of a conservative amino acid substitution?

Accepted Answer

Ser for Thr

Question 12

If a protein's function is lost after a single amino acid substitution, what does this suggest about the role of that amino acid?

Accepted Answer

It is likely critical for the protein's structure or active site.

Question 13

Which of the following substitutions is most likely to preserve the protein's function?

Accepted Answer

Thr for Ser

Question 14

What is the main reason that a change in the primary structure of a protein can affect its tertiary structure?

Accepted Answer

The sequence of amino acids determines how the protein folds.

Question 15

Which of the following is NOT a possible consequence of altering the primary structure of a protein?

Accepted Answer

Increase in protein's DNA content

Question 16

A protein sequence is changed from Lys-Gly-Asp to Lys-Gly-Glu. What is the most likely effect?

Accepted Answer

Minimal effect, since Asp and Glu are both acidic amino acids.

Question 17

Which of the following best describes a non-conservative amino acid substitution?

Accepted Answer

Replacing a polar amino acid with a nonpolar amino acid

Question 18

If a protein's function is unaffected by a single amino acid substitution, what does this suggest?

Accepted Answer

The substituted amino acid has similar properties to the original.

Question 19

Which of the following is most likely to result from substituting a charged amino acid for a nonpolar amino acid in a protein?

Accepted Answer

Altered protein folding due to changes in electrostatic interactions.

Question 20

Which of the following statements about protein primary structure is correct?

Accepted Answer

It is the linear sequence of amino acids joined by peptide bonds.

Altering Primary Protein Structure and Its Effects

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