DNA Structure and Replication

What is the basic structural unit of DNA?

• Amino acid

• Nucleotide

• Protein

• Lipid

Which of the following components is NOT part of a nucleotide?

• Phosphate group

• Ribose sugar

• Nitrogenous base

• Deoxyribose sugar

Identify the correct base pairing in DNA.

• Adenine - Cytosine

• Guanine - Thymine

• Adenine - Thymine

• Cytosine - Thymine

Which enzyme is responsible for unwinding the DNA double helix during replication?

• DNA polymerase

• Helicase

• Ligase

• Primase

What is the role of DNA Polymerase III in DNA replication?

• Unwinds the DNA double helix

• Synthesizes RNA primers

• Joins Okazaki fragments

• Adds nucleotides to the growing DNA strand

Explain why DNA replication is considered semi-conservative.

• Each new DNA molecule contains two new strands.

• Each new DNA molecule contains one old strand and one new strand.

• Each new DNA molecule contains two old strands.

• Each new DNA molecule contains a mixture of old and new DNA within each strand.

Describe the role of ligase in DNA replication.

• Ligase synthesizes RNA primers.

• Ligase unwinds the DNA double helix.

• Ligase joins Okazaki fragments on the lagging strand.

• Ligase adds nucleotides to the growing DNA strand.

Which nitrogenous base is found in RNA but not in DNA?

• Thymine

• Uracil

• Adenine

• Guanine

What is the significance of the antiparallel nature of DNA strands?

• It allows the DNA to form a double helix.

• It enables the strands to be identical.

• It allows the strands to be complementary.

• It prevents the strands from separating.

Which enzyme synthesizes RNA primers during DNA replication?

• DNA polymerase

• Helicase

• Primase

• Ligase