Question 1

Which of the following best describes the 'one gene-one enzyme' hypothesis as originally proposed by Beadle and Tatum?

Accepted Answer

Each gene codes for a single enzyme that catalyzes a specific step in a metabolic pathway.

Question 2

A nutritional mutant of Neurospora crassa is unable to grow on minimal medium but grows when supplemented with arginine. Which gene is most likely mutated?

Accepted Answer

A gene encoding an enzyme required for the synthesis of arginine.

Question 3

Which of the following statements about the Central Dogma of molecular biology is correct?

Accepted Answer

Information flows from DNA to RNA to protein.

Question 4

During transcription, which enzyme synthesizes RNA from a DNA template?

Accepted Answer

RNA polymerase

Question 5

Which of the following best explains why a mutation in a gene can lead to an inherited metabolic disease?

Accepted Answer

A mutation may result in the production of a nonfunctional enzyme, blocking a metabolic pathway.

Question 6

Which of the following codons serves as both the start signal for translation and codes for methionine?

Accepted Answer

$$\mathrm{AUG}$$

Question 7

If a DNA template strand has the sequence $$3'	ext{-}TACGGTACG-5'$$, what is the sequence of the complementary mRNA produced during transcription?

Accepted Answer

$$5'	ext{-}AUGCCAUGC-3'$$

Question 8

Which process describes the synthesis of a polypeptide using the information in an mRNA molecule?

Accepted Answer

Translation

Question 9

A mutation changes a codon from $$\mathrm{UAC} to$$ $$\mathrm{UAA}. $$What is the likely effect on the resulting protein?

Accepted Answer

Translation will terminate prematurely, producing a truncated protein.

Question 10

Which of the following best describes the relationship between genotype and phenotype as explained by the Central Dogma?

Accepted Answer

Genotype determines the sequence of DNA, which is transcribed and translated to produce proteins that determine phenotype.

Question 11

Which of the following is NOT a property of the genetic code?

Accepted Answer

It is ambiguous, with each codon coding for more than one amino acid.

Question 12

Which of the following best explains why the genetic code is described as 'universal'?

Accepted Answer

All organisms use the same codons to specify the same amino acids, with very few exceptions.

Question 13

Which of the following is a direct result of a frameshift mutation in a gene?

Accepted Answer

A change in the reading frame, resulting in a completely different amino acid sequence downstream of the mutation.

Question 14

Which of the following best describes the function of mRNA in the process of gene expression?

Accepted Answer

It carries the genetic code from DNA to the ribosome for protein synthesis.

Question 15

Which of the following is a real-world application of the universality of the genetic code?

Accepted Answer

Inserting a firefly gene into a bacterium to produce a fluorescent protein.

Question 16

Which of the following best explains why Beadle and Tatum used minimal medium in their experiments with Neurospora crassa?

Accepted Answer

To identify mutants that could not synthesize specific nutrients and thus required supplementation.

Question 17

Which of the following is the correct sequence of events in the flow of genetic information according to the Central Dogma?

Accepted Answer

DNA $$\rightarrow$$ RNA $$\rightarrow$$ Protein

Question 18

Which of the following best describes the role of tRNA during translation?

Accepted Answer

It brings the correct amino acid to the ribosome by matching its anticodon to the mRNA codon.

Question 19

A scientist discovers a mutation that prevents the production of enzyme B in a metabolic pathway. According to the one gene-one enzyme hypothesis, what is the most likely consequence?

Accepted Answer

The pathway will be blocked at the step catalyzed by enzyme B, and the product will not be synthesized.

Gene Expression: From Gene to Protein – The Central Dogma and Genetic Code

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