Q: Which statement best describes the central dogma of molecular biology?

$$\text{DNA} \to \text{RNA} \to \text{protein}$$

Question 1

Which experiment provided the first direct evidence that DNA is the hereditary molecule in cells?

Accepted Answer

Avery et al.'s transformation experiments

Question 2

Beadle and Tatum's experiments with Neurospora crassa mutants led to which major hypothesis about gene function?

Accepted Answer

The one-gene, one-enzyme hypothesis

Question 3

In the Srb and Horowitz experiment, a mutant Neurospora strain could grow only when citrulline or arginine was added to the medium, but not with ornithine. Which enzyme is most likely defective in this mutant?

Accepted Answer

Enzyme 2 (converts ornithine to citrulline)

Question 4

Which statement best describes the central dogma of molecular biology?

Accepted Answer

$$	ext{DNA} 	o 	ext{RNA} 	o 	ext{protein}$$

Question 5

Which property of the genetic code allows for more than one codon to specify the same amino acid?

Accepted Answer

Redundancy

Question 6

A mutation changes a single base in a gene, but the resulting protein is unchanged. Which property of the genetic code explains this phenomenon?

Accepted Answer

The code is redundant

Question 7

If a gene is mutated such that its mRNA now contains a premature stop codon, what is the most likely outcome for the protein product?

Accepted Answer

A truncated (shorter) protein is produced

Question 8

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

Accepted Answer

Each codon codes for only one specific amino acid

Question 9

How many different codons are possible in the genetic code, given that there are four different RNA bases and each codon is three bases long?

Accepted Answer

$$4^3 = 64$

Question 10

Which of the following is a direct implication of the central dogma for heredity?

Accepted Answer

The genotype is determined by the sequence of nucleotides in DNA

Question 11

A scientist introduces a single-base insertion mutation into a gene. What is the most likely effect on the resulting protein?

Accepted Answer

The reading frame will shift, altering all downstream amino acids

Question 12

Which experiment demonstrated that single-stranded DNA can serve as a template for RNA synthesis?

Accepted Answer

An in vitro experiment using a DNA template of thymine and RNA polymerase

Question 13

Which of the following codons is the start codon in the genetic code?

Accepted Answer

AUG

Question 14

Why is the genetic code described as nearly universal?

Accepted Answer

With few exceptions, all organisms use the same codons for the same amino acids

Question 15

Which of the following best describes the role of mRNA in the flow of genetic information?

Accepted Answer

It carries genetic information from DNA to the ribosome for protein synthesis

Question 16

A mutation in a gene changes the codon UAU (tyrosine) to UAA. What is the result of this mutation?

Accepted Answer

Translation will terminate at this codon, producing a shorter protein

Question 17

Which of the following statements about alleles is correct according to the central dogma?

Accepted Answer

Alleles differ in their DNA sequence, which can lead to differences in the proteins produced

Question 18

Which property of the genetic code ensures that the amino acid sequence encoded by a DNA or RNA sequence can be predicted?

Accepted Answer

Predictability

Question 19

If a gene's DNA sequence is 5'-ATG GGC TAA-3', what is the corresponding mRNA sequence produced during transcription?

Accepted Answer

$$5'	ext{-AUG GGC UAA-}3'$$

Question 20

Which of the following best explains why a three-base codon is necessary to encode all 20 amino acids?

Accepted Answer

There are only 4 possible bases, so 2-base codons would only allow $$4^2 = 16$ combinations, which is not enough

BIO181- 5.2: Gene Function (Unit 5: Genetic Principles)

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