Question 1

Which of the following best describes the difference between ribose and deoxyribose nucleotides?

Accepted Answer

Ribose contains a hydroxyl group at the 2' carbon, while deoxyribose lacks this group.

Question 2

A DNA molecule is found to have 30% adenine. According to Chargaff's rules, what percentage of guanine would you expect in this molecule?

Accepted Answer

20%

Question 3

Which enzyme is responsible for synthesizing the RNA primer during DNA replication in E. coli?

Accepted Answer

Primase

Question 4

During DNA replication, Okazaki fragments are formed on the lagging strand. Which enzyme is responsible for joining these fragments together?

Accepted Answer

DNA ligase

Question 5

If a DNA sequence reads 5'-ATGCCGTA-3', what is the sequence of the complementary strand?

Accepted Answer

3'-TACGGCAT-5'

Question 6

Which of the following best describes the Meselson-Stahl experiment's conclusion about DNA replication?

Accepted Answer

DNA replication is semi-conservative, with each daughter molecule containing one parental and one new strand.

Question 7

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 8

Which of the following is a function of DNA polymerase III in E. coli?

Accepted Answer

5' to 3' polymerization activity

Question 9

A patient is diagnosed with xeroderma pigmentosum, a disorder caused by defective nucleotide excision repair. Which type of DNA damage is most likely to accumulate in their cells?

Accepted Answer

Thymine dimers caused by UV light

Question 10

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

Accepted Answer

It is degenerate, meaning multiple codons can code for the same amino acid.

Question 11

Which process is responsible for removing introns from pre-mRNA in eukaryotes?

Accepted Answer

Splicing

Question 12

A frameshift mutation is most likely to result from which of the following?

Accepted Answer

Insertion of a single nucleotide

Question 13

Which of the following enzymes is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 14

In a gene, the coding strand has the sequence 5'-ATG GCT TAA-3'. What is the sequence of the mRNA produced from this gene?

Accepted Answer

5'-AUG GCU UAA-3'

Question 15

Which of the following best describes a transition mutation?

Accepted Answer

A purine is replaced by another purine, or a pyrimidine by another pyrimidine.

Question 16

Which of the following is NOT a function of the 3' to 5' exonuclease activity of DNA polymerase?

Accepted Answer

Joining Okazaki fragments

Question 17

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

Accepted Answer

Initiation of transcription

Question 18

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

Accepted Answer

Phosphorylation

Question 19

Which repair system is responsible for correcting mismatched bases that escape proofreading during DNA replication?

Accepted Answer

Mismatch repair

Question 20

If a transposable element inserts itself into the coding region of a gene, what is the most likely consequence?

Accepted Answer

Disruption of gene function, potentially leading to a loss-of-function mutation

Core Concepts in Genetics: DNA Structure, Replication, Transcription, Translation, and Mutation

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