Chapter 7: The Blueprint of Life, from DNA to Protein: Replication

Question 1

What is DNA replication?

Answer 1

• one parental double stranded DNA molecule is used to make 2 identical double stranded DNA molecules

Question 2

Since the DNA strands are complementary, what can occur?

Answer 2

• one strand can serve as a template for the synthesis of the other strand

Question 3

What does DNA polymerase do in replication?

Answer 3

• reads the order of nucleotides in the template strand to make a complementary new strand

Question 4

What are the first steps in replication?

Answer 4

1. A small segment of dsDNA unwinds and the strands are separated
   - this forms the replication fork
   - each separated strand serves as a template for synthesis of a complementary strand
2. A short RNA primer is produced by enzyme primase

Question 5

Is DNA replication continuous?

Answer 5

no

Question 6

How is the leading strand synthesized? (3)

Answer 6

• DNA polymerase can only synthesize DNA in the 5’ to 3’ direction
• so template must be read in the 3’ to 5’ direction
• follows the replication fork

Question 7

Is the synthesis of the leading strand continuous?

Answer 7

yes, in the 5’ to 3’ direction

Question 8

Why must the lagging strand be made in the opposite direction?

Answer 8

• DNA polymerase can only make DNA in the 5’ to 3’ direction

Question 9

How is the lagging strand synthesized? (2)

Answer 9

1. DNA polymerase synthesizes small fragments of DNA called Okazaki fragments, which are made in 5’ to 3’ direction
2. RNA primers are removed and the fragments are joined by enzyme DNA ligase