Q: According to the central dogma of molecular biology, what is the correct flow of genetic information in a cell?

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

Q: Given the DNA template strand $$3'\text{-TACGGTACGTTTATT-}5'$$, what is the corresponding mRNA sequence?

$$5'\text{-AUGCCAUGCAAAUAA-}3'$$

Question 1

Which experiment led to the formulation of the one-gene, one-enzyme hypothesis, and what was the main finding?

Accepted Answer

Beadle and Tatum irradiated bread mold and found that each mutant lacked a specific enzyme in the arginine synthesis pathway.

Question 2

According to the central dogma of molecular biology, what is the correct flow of genetic information in a cell?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 3

Which of the following best describes the role of messenger RNA (mRNA) in gene expression?

Accepted Answer

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

Question 4

A mutation changes the DNA sequence from $$	ext{TAT} to$$ $$	ext{TAC}$$, but both code for tyrosine. What type of mutation is this?

Accepted Answer

Silent mutation

Question 5

Which property of the genetic code ensures that most amino acids are specified by more than one codon?

Accepted Answer

Redundancy

Question 6

A point mutation results in a codon that previously coded for glutamine ($$	ext{CAA}) $$now coding for a stop codon ($$	ext{UAA}). $$What is the consequence?

Accepted Answer

The protein will be prematurely terminated due to a nonsense mutation.

Question 7

Which of the following mutations is most likely to result in a nonfunctional protein?

Accepted Answer

Frameshift mutation

Question 8

If a segment of a chromosome breaks off, flips around, and rejoins, what type of chromosomal mutation has occurred?

Accepted Answer

Inversion

Question 9

Which enzyme is responsible for synthesizing RNA from a DNA template during transcription?

Accepted Answer

RNA polymerase

Question 10

A scientist observes that a certain mutation does not change the amino acid sequence of the resulting protein. What is the most likely explanation?

Accepted Answer

The mutation is silent due to the redundancy of the genetic code.

Question 11

Which of the following best explains why the central dogma is sometimes modified in viruses?

Accepted Answer

Some viruses use reverse transcriptase to synthesize DNA from an RNA template.

Question 12

A mutation in a regulatory region of DNA does not change the protein sequence but alters the amount of protein produced. What is the likely effect on phenotype?

Accepted Answer

The phenotype may change due to altered gene expression.

Question 13

Given the DNA template strand $$3'	ext{-TACGGTACGTTTATT-}5'$$, what is the corresponding mRNA sequence?

Accepted Answer

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

Question 14

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

Accepted Answer

Each codon can code for more than one amino acid.

Question 15

A patient’s karyotype reveals an extra copy of chromosome 21. What type of chromosomal mutation is this?

Accepted Answer

Aneuploidy

Question 16

Which of the following best describes a missense mutation?

Accepted Answer

A point mutation that results in a different amino acid in the protein sequence.

Question 17

If the mRNA codon is $$	ext{AUG}$$, what amino acid is incorporated during translation?

Accepted Answer

Methionine

Question 18

Which type of mutation is most likely to be neutral with respect to fitness?

Accepted Answer

Silent mutation

Question 19

A segment of a chromosome is present in multiple copies. What type of chromosomal mutation is this?

Accepted Answer

Duplication

Question 20

Which of the following scenarios best illustrates the connection between genotype and phenotype?

Accepted Answer

A change in DNA sequence alters the amino acid sequence of a protein, resulting in a different coat color in mice.

How Genes Work: Molecular Basis, Genetic Code, and Mutations

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