DNA Synthesis

Part A

What catalyzes DNA synthesis?

	DNA polymerase
	Replication fork
	Primer
	dNTPs

Correct

This enzyme catalyzes DNA synthesis.

Part B

Which of the following statements about DNA synthesis is true?

	As DNA polymerase moves along the template strand, each new nucleotide provides a 5’ hydroxyl group for the next reaction to occur.
	Primers are short sequences that allow the initiation of DNA synthesis.
	DNA polymerase adds dNTP monomers in the 3’ to 5’ direction.
	Nucleotides are added in a random fashion to single-stranded DNA.

Correct

When a primer is added to a single strand of DNA, DNA polymerase can start adding nucleotides to synthesize a complementary strand.

Part C

Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis?

	Base
	Phosphate groups
	Free 3' hydroxyl (–OH) group
	Sugar

Correct

The potential energy stored in the bonds of the phosphates provides the energy for DNA synthesis.

Part D

Which of the following enzymes creates a primer for DNA polymerase?

	Ligase
	Helicase
	Topoisomerase
	Primase

Correct

This RNA polymerase synthesizes an RNA primer antiparallel to the template DNA strand.

Part E

Which of the following statements about Okazaki fragments in E. coli is true?

	They are formed on the lagging strand of DNA.
	They are usually 50 to 500 bases long.
	They are synthesized in the 3’ to 5’ direction.
	They are sealed together by the action of helicase.

Correct

While DNA is synthesized continuously on the leading strand, Okazaki fragments are formed on the lagging strand because DNA synthesis always proceeds in the 5’ to 3’ direction.

Part F

Which of the following enzymes is important for relieving the tension in a helix as it unwinds during DNA synthesis?

	Single-stranded binding proteins
	Helicase
	Topoisomerase
	Ligase

Correct

This enzyme untwists the coils that occur in the DNA as it is being unwound into a single-stranded template.

Part G

True or false? Single-stranded DNA molecules are said to be antiparallel when they are lined up next to each other but oriented in opposite directions.

	True
	False

Correct

When the 3’ end of one DNA strand points in the same direction as the 5’ end of the other DNA strand, the strands are said to be antiparallel.