DNA Structure and Replication Quiz

Which base pairs with adenine in the DNA double helix?

• Guanine

• Thymine

• Cytosine

• Uracil

If one strand of DNA has the sequence 5'-ATCGGTA-3', what is the complementary sequence on the other strand?

• 5'-TACCGAT-3'

• 3'-TAGCCAT-5'

• 5'-TAGCCAT-3'

• 3'-ATCGGTA-5'

During DNA replication, which enzyme is responsible for adding new nucleotides to the growing DNA strand?

• Helicase

• DNA polymerase

• Ligase

• Primase

What would happen if the enzyme helicase did not function during DNA replication?

• The DNA would not unwind, and replication could not begin.

• New nucleotides would not be added to the strand.

• The DNA fragments would not be joined together.

• The RNA primer would not be created.

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

• 3' to 5' direction

• 5' to 3' direction

• Both directions at the same time

• Randomly

If a DNA molecule is composed of 30% adenine, what percentage of thymine would you expect to find?

• 20%

• 30%

• 40%

• 50%

Which statement explains why DNA replication is called "semi-conservative"?

• Each new DNA molecule contains two new strands.

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

• Both strands are completely new.

• Only one strand is copied.

What is the role of DNA ligase during DNA replication?

• Unwinds the DNA double helix

• Adds nucleotides to the new strand

• Joins Okazaki fragments on the lagging strand

• Synthesizes RNA primers

If a mutation changes a cytosine to a thymine in a DNA sequence, which base will now pair with the mutated base during replication?

• Guanine

• Adenine

• Thymine

• Cytosine

Why is it important that DNA replication occurs before a cell divides?

• To ensure each new cell has a complete set of DNA

• To create more proteins

• To break down old DNA

• To remove mutations