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

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

Question 1

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

Accepted Answer

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

Question 2

A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this, and what is the likely effect on the protein?

Accepted Answer

Nonsense mutation; the protein will be prematurely terminated

Question 3

During transcription in eukaryotes, which of the following modifications occurs to the pre-mRNA before it leaves the nucleus?

Accepted Answer

Addition of a 5' cap and a poly-A tail

Question 4

Which enzyme is responsible for catalyzing the synthesis of RNA from a DNA template during transcription?

Accepted Answer

RNA polymerase

Question 5

A DNA template strand has the sequence 3'-TACGGTACG-5'. What is the corresponding mRNA sequence produced during transcription?

Accepted Answer

5'-AUGCCAUGC-3'

Question 6

Which of the following statements about the genetic code is TRUE?

Accepted Answer

The code is redundant but not ambiguous

Question 7

In prokaryotes, what is a key difference in gene expression compared to eukaryotes?

Accepted Answer

Translation can begin before transcription is complete

Question 8

A tRNA molecule with the anticodon 3'-UAC-5' will carry which amino acid?

Accepted Answer

Methionine

Question 9

Which of the following best explains why a frameshift mutation is often more severe than a point substitution?

Accepted Answer

It alters the reading frame, changing every amino acid downstream

Question 10

What is the function of the spliceosome in eukaryotic cells?

Accepted Answer

It removes introns and joins exons in pre-mRNA

Question 11

A scientist inserts a jellyfish gene into a mosquito, and the mosquito expresses a glowing protein. What does this demonstrate about the genetic code?

Accepted Answer

The genetic code is universal among organisms

Question 12

Which of the following is a post-translational modification that can affect protein function?

Accepted Answer

Glycosylation (addition of sugars)

Question 13

A mutation in the promoter region of a gene most likely affects which process?

Accepted Answer

The initiation of transcription

Question 14

Which of the following best describes the role of aminoacyl-tRNA synthetase?

Accepted Answer

It attaches the correct amino acid to its tRNA

Question 15

If a DNA coding strand has the sequence 5'-ATG GAA TGA-3', what is the sequence of the mRNA and the first three amino acids of the polypeptide?

Accepted Answer

mRNA: 5'-AUG GAA UGA-3'; amino acids: Met-Glu-Stop

Question 16

Which of the following is NOT a function of the 5' cap and poly-A tail added to eukaryotic mRNA?

Accepted Answer

Direct the splicing of introns

Question 17

Which of the following best explains why a silent mutation does not affect the phenotype?

Accepted Answer

It does not change the amino acid sequence due to redundancy in the genetic code

Question 18

What is the role of the signal-recognition particle (SRP) during translation?

Accepted Answer

It directs ribosomes to the endoplasmic reticulum for protein targeting

Question 19

Which of the following best describes a polyribosome (polysome)?

Accepted Answer

Multiple ribosomes translating a single mRNA simultaneously

Question 20

A patient has a genetic disorder caused by a single nucleotide deletion in a gene. Which of the following is the most likely consequence at the protein level?

Accepted Answer

The protein is truncated due to a premature stop codon from a frameshift

Gene Expression: Transcription, Translation, and Mutations

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