Quiz: DNA Replication and Mutation Fundamentals — 9 domande

1. During DNA replication, which enzyme is responsible for synthesizing new DNA strands?

A. DNA polymerase

B. Helicase

C. Ligase

D. Topoisomerase

Answer: (A)

Spiegazione

DNA polymerase is the enzyme that synthesizes new DNA strands by adding nucleotides complementary to the template strand during replication.

2. What is the primary function of DNA polymerase during replication?

A. It unwinds the DNA double helix.

B. It synthesizes new DNA strands by adding complementary nucleotides.

C. It primes DNA synthesis with RNA primers.

D. It proofreads and repairs DNA mismatches.

Answer: (B)

Spiegazione

DNA polymerase is responsible for synthesizing new DNA strands by adding nucleotides complementary to the template, ensuring accurate replication.

3. What is the primary structural characteristic of DNA?

A. Double helix with complementary strands

B. Triple helix with repeating units

C. Single-stranded helix with unpaired bases

D. Linear chain with random bases

Answer: (A)

Spiegazione

DNA's primary structure is a double helix composed of two complementary nucleotide strands. The bases pair specifically (A with T, C with G), forming the characteristic double helix.

4. Which feature correctly describes the replication speed in eukaryotic cells?

A. Approximately 10 nucleotides per second.

B. Approximately 100 nucleotides per second.

C. Less than 1,000 nucleotides per second.

D. Exactly 50 nucleotides per second.

Answer: (B)

Spiegazione

Eukaryotic DNA replication occurs at about 100 nucleotides/sec, which balances speed with fidelity for large genomes.

5. What type of mutation involves the removal of one or more nucleotides from the DNA sequence?

A. Addition

B. Substitution

C. Deletion

D. Duplication

Answer: (C)

Spiegazione

A deletion mutation involves the removal of nucleotides from the DNA sequence, which can disrupt the reading frame and affect gene function.

6. What is the role of primase during DNA replication?

A. It synthesizes the main DNA strand continuously.

B. It unwinds the DNA helix.

C. It synthesizes RNA primers to initiate replication.

D. It proofreads newly synthesized DNA.

Answer: (C)

Spiegazione

Primase synthesizes RNA primers that serve as starting points for DNA polymerase to begin DNA synthesis.

7. Which statement most accurately describes a mutation?

A. A mutation always causes disease.

B. Mutations are changes to the genetic sequence, which can be substitutions, insertions, or deletions.

C. Mutations are exclusively caused by environmental mutagens.

D. Mutations only occur during DNA replication.

Answer: (B)

Spiegazione

Mutations are alterations in DNA sequences, including substitutions, insertions, and deletions, which can occur naturally or due to mutagens.

8. How does the semi-conservative nature of DNA replication manifest in daughter molecules?

A. Each daughter DNA contains only new strands.

B. Each daughter DNA contains one original and one new strand.

C. Both strands in daughter DNA are identical and new.

D. Daughter DNA molecules are entirely conserved from the parent.

Answer: (B)

Spiegazione

Semi-conservative replication results in each daughter DNA molecule having one original strand and one newly synthesized strand.

9. Which of the following best describes the purpose of the "replication fork"?

A. It is the point where DNA synthesis initiates.

B. It is a Y-shaped structure where DNA unwinding and replication occur.

C. It is the enzyme that synthesizes the new DNA strand.

D. It terminates DNA replication.

Answer: (B)

Spiegazione

The replication fork is the Y-shaped structure where the DNA double helix unwinds, allowing replication to take place on both strands.