$$\text{Ornithine} \rightarrow \text{Citrulline} \rightarrow \text{Arginine}$$

Question 1

Which region of a eukaryotic mRNA transcript is NOT translated into protein?

Accepted Answer

The 5'-UTR and 3'-UTR

Question 2

Which amino acid is classified as nonpolar and hydrophobic?

Accepted Answer

Valine (V)

Question 3

What type of bond links amino acids together in a protein?

Accepted Answer

Peptide bond

Question 4

Which level of protein structure is primarily determined by the sequence of amino acids?

Accepted Answer

Primary structure

Question 5

Alpha helices and beta sheets are stabilized mainly by which type of interaction?

Accepted Answer

Hydrogen bonds

Question 6

A mutation in the gene encoding phenylalanine hydroxylase leads to which metabolic disorder?

Accepted Answer

Phenylketonuria (PKU)

Question 7

Which amino acid is polar and positively charged at physiological pH?

Accepted Answer

Arginine (R)

Question 8

In the arginine biosynthesis pathway in Neurospora, which compound would rescue an arg2 mutant if added to minimal medium?

Accepted Answer

Citrulline

Question 9

Which statement best describes the 'one gene: one enzyme' hypothesis?

Accepted Answer

Each gene encodes a single enzyme that affects a specific metabolic pathway

Question 10

Which of the following is a real-world consequence of untreated PKU in infants?

Accepted Answer

Intellectual disability due to accumulation of phenylpyruvic acid

Question 11

Which amino acid contains a sulfur atom in its side chain?

Accepted Answer

Methionine (M)

Question 12

What is the correct order of intermediates in the arginine biosynthesis pathway in Neurospora?

Accepted Answer

$$	ext{Ornithine} ightarrow 	ext{Citrulline} ightarrow 	ext{Arginine}$$

Question 13

Which of the following best explains why Neurospora is useful for genetic studies of metabolic pathways?

Accepted Answer

Its spores are haploid, so mutations are directly expressed

Question 14

Which amino acid is polar and negatively charged at physiological pH?

Accepted Answer

Aspartic acid (D)

Question 15

A protein composed of two alpha and two beta subunits, such as hemoglobin, demonstrates which level of protein structure?

Accepted Answer

Quaternary structure

Question 16

Which of the following is a direct result of a block in a metabolic pathway due to a gene mutation?

Accepted Answer

Accumulation of the substrate before the block

Question 17

Which of the following best describes a prototroph in the context of Neurospora genetics?

Accepted Answer

A strain that can grow on minimal medium without supplementation

Question 18

Which chemical group is present in all amino acids and is responsible for peptide bond formation?

Accepted Answer

Carboxyl group ($$-COOH)$$

Question 19

If a Neurospora mutant cannot convert ornithine into citrulline, which compound(s) would you add to minimal medium to restore growth?

Accepted Answer

Citrulline or arginine

Question 20

Which of the following is a real-life example of a metabolic disorder caused by a single gene mutation affecting an enzyme?

Accepted Answer

Phenylketonuria (PKU)

Gene Function and Protein Structure: Oct 27

Study Guide - Practice Questions