Question 1

Which of the following best explains why sulfur and phosphorus were chosen as radioactive labels in the Hershey-Chase experiment?

Accepted Answer

Sulfur is found in proteins but not in DNA, and phosphorus is found in DNA but not in proteins.

Question 2

A scientist discovers a nucleic acid molecule with the following characteristics: it contains ribose sugar, uracil, and is single-stranded. Which type of molecule is this most likely to be?

Accepted Answer

RNA

Question 3

Which of the following statements about the structure of DNA is correct?

Accepted Answer

Adenine pairs with thymine via hydrogen bonds, and the strands are antiparallel.

Question 4

What was the key finding from the Meselson-Stahl experiment regarding DNA replication?

Accepted Answer

DNA replication is semiconservative, with each new molecule containing one parental and one new strand.

Question 5

Which of the following best describes the difference between a purine and a pyrimidine?

Accepted Answer

Purines (adenine and guanine) have a double ring structure, while pyrimidines (cytosine and thymine) have a single ring structure.

Question 6

A mutation changes a DNA codon from $$\mathrm{AAA} to$$ $$\mathrm{AAG}$$, but both codons code for lysine. What type of mutation is this?

Accepted Answer

Silent mutation

Question 7

Which of the following processes occurs during the maturation of pre-mRNA in eukaryotic cells?

Accepted Answer

Addition of a 5’ cap and a poly-A tail, and removal of introns

Question 8

If a DNA strand has the sequence $$5'	ext{-}ATCGGTA-3'$$, what is the complementary DNA strand sequence?

Accepted Answer

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

Question 9

Which enzyme is responsible for synthesizing short RNA primers during DNA replication?

Accepted Answer

Primase

Question 10

A mutation causes the insertion of a single nucleotide early in the coding region of a gene. What is the most likely consequence?

Accepted Answer

A frameshift mutation that alters the reading frame and likely disrupts protein function

Question 11

Which of the following best explains why a purine must always pair with a pyrimidine in DNA?

Accepted Answer

To ensure the DNA molecule has a uniform diameter

Question 12

Which of the following is NOT a difference between DNA and RNA?

Accepted Answer

DNA contains phosphate groups, while RNA does not.

Question 13

Which of the following best describes the function of the spliceosome?

Accepted Answer

It removes introns from pre-mRNA and joins exons together.

Question 14

A point mutation in an exon changes a codon from $$\mathrm{UAC} ($$tyrosine) to $$\mathrm{UAA} ($$stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 15

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

Accepted Answer

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

Question 16

During translation, which site on the ribosome does the incoming aminoacyl-tRNA first bind?

Accepted Answer

A site

Question 17

Which of the following best describes the role of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments together on the lagging strand.

Question 18

A patient has a mutation in the gene encoding a tRNA synthetase. Which process is most likely to be directly affected?

Accepted Answer

Attachment of amino acids to their corresponding tRNAs

Question 19

Which of the following scenarios would most likely result in the least disruption of gene function?

Accepted Answer

A silent mutation in an exon

Question 20

Which of the following best describes the direction in which DNA polymerase synthesizes new DNA?

Accepted Answer

It synthesizes DNA in the $$5' \rightarrow 3'$$ direction.

BIO 1150 Exam 6 Study Guide – DNA, RNA, and Mutations

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