Question 1

Which experiment provided the first strong evidence that DNA is the genetic material, and what was the key result that supported this conclusion?

Accepted Answer

Hershey and Chase's experiment, which demonstrated that radioactive phosphorus (in DNA) entered bacterial cells during viral infection.

Question 2

What does it mean to say that DNA replication is semiconservative?

Accepted Answer

Each new DNA molecule contains one parental strand and one newly synthesized strand.

Question 3

Which of the following best describes Chargaff's Rule?

Accepted Answer

The amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine in DNA.

Question 4

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

Accepted Answer

Nonsense mutation; introduces a premature stop codon, truncating the protein.

Question 5

What is the function of the release factor during translation?

Accepted Answer

It recognizes the stop codon and promotes the release of the completed polypeptide from the ribosome.

Question 6

Which statement best explains why the genetic code is described as 'redundant but not ambiguous'?

Accepted Answer

Multiple codons can code for the same amino acid, but each codon specifies only one amino acid.

Question 7

What is the role of the TATA box in eukaryotic transcription?

Accepted Answer

It serves as a promoter region where transcription factors and RNA polymerase bind to initiate transcription.

Question 8

Which process allows a single gene to produce multiple different proteins in eukaryotes?

Accepted Answer

Alternative RNA splicing

Question 9

If a DNA strand has the sequence 5'-ATCGGTA-3', what is the complementary strand produced during replication?

Accepted Answer

3'-TAGCCAT-5'

Question 10

Which enzyme is responsible for synthesizing the RNA primer during DNA replication?

Accepted Answer

Primase

Question 11

What is the difference between exons and introns in eukaryotic genes?

Accepted Answer

Exons are coding regions that remain in mature mRNA; introns are non-coding regions removed during RNA splicing.

Question 12

Which of the following best describes the Central Dogma of molecular biology?

Accepted Answer

$$DNA \rightarrow RNA \rightarrow Protein$$

Question 13

A scientist observes that recombination frequency between two genes is 50%. What does this indicate about the location of these genes?

Accepted Answer

The genes are located far apart on the same chromosome or on different chromosomes.

Question 14

Which of the following is a real-world application of recombinant DNA technology?

Accepted Answer

Producing human insulin in bacteria for diabetes treatment.

Question 15

What is the function of telomerase in eukaryotic cells?

Accepted Answer

It adds repetitive nucleotide sequences to the ends of chromosomes to prevent shortening during replication.

Question 16

Which of the following statements about antiparallel DNA strands is correct?

Accepted Answer

One strand runs 5' to 3', and the other runs 3' to 5'.

Question 17

Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

Ligase

Question 18

What is a gene linkage map, and how is it constructed?

Accepted Answer

A diagram showing the relative positions of genes based on recombination frequencies, constructed using genetic crosses.

Question 19

Which of the following best explains why males are more affected by X-linked traits than females?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will result in the trait being expressed.

Question 20

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

Accepted Answer

RNA splicing

Genetics and Molecular Biology: Study Guide for Chapters 15-17

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