Quiz: Genetics Fundamentals: DNA to Protein — 10 questions

1. What is the structure of DNA primarily characterized as?

A. A triple-stranded helix with three nucleotide chains.

B. A double helix, with two strands twisted into a spiral.

C. A single, linear strand of nucleotides.

D. A flat, sheet-like arrangement of nucleotides.

Answer: (B)

Explanation

DNA's structure is primarily characterized as a double helix, a three-dimensional spiral staircase formed by two complementary strands twisted around each other. This structure was discovered by Watson and Crick in 1953 and is fundamental to its function in storing genetic information.

2. Who discovered the double helix structure of DNA, and in what year?

A. Watson and Crick in 1953

B. Franklin and Wilkins in 1962

C. 孟德尔 in 1865

D. Chargaff in 1950

Answer: (A)

Explanation

Watson and Crick discovered the double helix structure of DNA in 1953, which was a landmark achievement in genetics, building on the earlier work of Rosalind Franklin and others.

3. Which enzyme is primarily responsible for synthesizing new DNA strands during DNA replication?

A. DNA helicase

B. DNA ligase

C. Primase

D. DNA polymerase

Answer: (D)

Explanation

DNA polymerase is the enzyme that synthesizes new DNA strands by adding nucleotides complementary to the template strand during DNA replication. It is essential for the formation of the new DNA molecule, making it the primary enzyme responsible for DNA synthesis.

4. What are nucleotides composed of?

A. A phosphate group, a sugar, and a nitrogenous base

B. A protein, a lipid, and a carbohydrate

C. A peptide chain and a cell membrane component

D. A hydrogen atom, a carbon atom, and an oxygen atom

Answer: (A)

Explanation

Nucleotides are the basic building blocks of DNA, consisting of a phosphate group, a deoxyribose sugar, and a nitrogenous base.

5. What is the primary function of RNA transcription in the cell?

A. To translate mRNA into amino acids during protein synthesis

B. To produce RNA molecules that carry genetic information for protein synthesis

C. To modify DNA sequences through mutation

D. To replicate DNA during cell division

Answer: (B)

Explanation

The main role of RNA transcription is to produce RNA molecules, particularly mRNA, which carry genetic information from DNA to the ribosomes for protein synthesis. It is not involved in DNA replication, translation, or mutation.

6. Which base pairs with Thymine in DNA?

A. Adenine

B. Cytosine

C. Guanine

D. Uracil

Answer: (A)

Explanation

Adenine pairs specifically with Thymine in DNA through hydrogen bonds, following the base pairing rules.

7. What is the significance of DNA being antiparallel?

A. It allows for the structural stability of the double helix.

B. It enables enzymes like DNA polymerase to synthesize DNA efficiently.

C. It prevents mutations from occurring during replication.

D. It causes the DNA strands to separate during cell division.

Answer: (B)

Explanation

The antiparallel orientation of DNA strands is crucial for enzymatic functions like DNA replication because it ensures the correct positioning of nucleotide synthesis.

8. During DNA replication, what is the role of DNA ligase?

A. Unwinds the DNA double helix.

B. Adds nucleotides to the growing DNA strand.

C. Joins Okazaki fragments on the lagging strand.

D. Synthesizes RNA primers.

Answer: (C)

Explanation

DNA ligase joins Okazaki fragments on the lagging strand, completing the synthesis of the continuous DNA strand.

9. Which of the following enzymes unwinds the DNA double helix at the replication fork?

A. DNA helicase

B. DNA polymerase

C. Ligase

D. Primase

Answer: (A)

Explanation

DNA helicase unwinds the double helix at the replication fork, allowing replication to proceed.

10. What is the primary function of DNA during cell division?

A. Storing and transmitting genetic information

B. Synthesizing proteins directly

C. Transporting nutrients into the cell

D. Providing energy for cellular processes

Answer: (A)

Explanation

DNA's main role during cell division is to store and transmit genetic information to ensure each new cell has an accurate copy.