Question 1

Archibald Garrod described alkaptonuria as an 'inborn error of metabolism.' What evidence led him to this conclusion?

Accepted Answer

The disease ran in families and was not caused by germs, suggesting a genetic basis.

Question 2

Which of the following best describes the primary structure of a protein?

Accepted Answer

The linear sequence of amino acids joined by covalent peptide bonds.

Question 3

A mutation in the gene encoding phenylalanine hydroxylase (PAH) leads to which human disease?

Accepted Answer

Phenylketonuria (PKU)

Question 4

Which of the following equations correctly represents the formation of a peptide bond between two amino acids?

Accepted Answer

$$\mathrm{Amino\ acid}_1 + \mathrm{Amino\ acid}_2 \rightarrow \mathrm{Dipeptide} + \mathrm{H}_2\mathrm{O}$$

Question 5

In the context of protein folding, which amino acids are most likely to be found on the interior of a globular protein?

Accepted Answer

Nonpolar amino acids

Question 6

Beadle and Tatum’s experiments with Neurospora crassa led to which important genetic hypothesis?

Accepted Answer

The one gene–one enzyme hypothesis

Question 7

A Neurospora mutant can grow on minimal medium supplemented with citrulline but not with ornithine. What does this indicate about the mutant?

Accepted Answer

It has a mutation in the enzyme that converts ornithine to citrulline.

Question 8

Which of the following best explains why sickle cell anemia persists at high frequencies in certain populations?

Accepted Answer

The sickle cell allele confers resistance to malaria in heterozygotes.

Question 9

Which of the following statements about enzymes is FALSE?

Accepted Answer

Enzymes are consumed during the reactions they catalyze.

Question 10

A single base pair change in the DNA sequence of the beta hemoglobin gene causes sickle cell anemia. What is the specific amino acid change?

Accepted Answer

Glutamic acid to valine at position 6

Question 11

Which of the following best describes an auxotrophic mutant in Neurospora?

Accepted Answer

A strain that requires an additional nutrient because it cannot synthesize it

Question 12

Which disease is caused by a defect in the lysosomal enzyme N-acetylhexosaminidase A (HEXA)?

Accepted Answer

Tay-Sachs disease

Question 13

Which of the following is a direct consequence of a mutation that inactivates an enzyme in a metabolic pathway?

Accepted Answer

The substrate for the missing enzyme accumulates.

Question 14

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

$$\mathrm{DNA} \rightarrow \mathrm{RNA} \rightarrow \mathrm{Protein}$$

Question 15

Which of the following is NOT a function of proteins in the cell?

Accepted Answer

Storing genetic information

Question 16

Which of the following best explains why charged and polar amino acids are generally found on the surface of proteins?

Accepted Answer

They are hydrophilic and interact with the aqueous environment.

Question 17

A child is diagnosed with PKU and placed on a special diet. What is the rationale for this treatment?

Accepted Answer

To prevent the accumulation of phenylalanine, which can cause brain damage

Question 18

Which of the following statements about the quaternary structure of proteins is TRUE?

Accepted Answer

It involves the assembly of multiple polypeptide subunits into a functional complex.

Question 19

Which of the following best describes the relationship between genotype and phenotype as explained by the central dogma?

Accepted Answer

Genotype determines phenotype through the production of specific proteins.

Question 20

Which of the following is a real-world example of how genetic screening has reduced the prevalence of a genetic disease?

Accepted Answer

Screening for Tay-Sachs disease alleles in populations with high carrier frequency

Genes, Proteins, Enzymes, and Human Disease: Molecular Genetics Study Guide

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