UNIT 1: Key Area 2 a) replication of DNA by DNA polymerase and primers

Question 1

define DNA replication

Answer 1

DNA can reproduce itself exactly
this is the replication process

Question 2

what is DNA replicated by before cell division ?

Answer 2

DNA polymerase

Question 3

what does DNA polymerase need in order to stop replication?

Answer 3

primer

Question 4

what is a primer ?

Answer 4

short strand of Nucleotides which binds to 3’ end of original DNA strand
allowing polymerase to add nucleotides

Question 5

why is DNA replication considered semi conservative?

Answer 5

because each new molecule contains one new and one original strand

Question 6

when does DNA replication take place ?

Answer 6

before mitosis

Question 7

how does DNA replicate?

Answer 7

DNA polymerase adds nucleotides according to base pairs
A-T G-C

Question 8

name the stages of DNA replication

Answer 8

1. DNA molecule unwinds
2. weak hydrogen bonds between bases break allowing two strands to seperate
3. this forms two template strands these are now a Y-shaped replication fork
4. Primer attached (a short series of nucleotides) joins to the 3’ end of original DNA
   5.DNA polymerase adds free nucleotides to the new strand

FORMATION OF NEW STRAND

6. synthesis occurs in a 5’ to 3’ direction (on the new strand)
7. The DNA nucleotides will then bind to their complementary bases on the template strand

FORMATION OF LAGGING STRAND

8. DNA polmerase is only able to add nucleotides to the free 3’ end of a growing strand
9. once the fragments are complete the primer is replaced by DNA
10. the fragments are then joined together by and enzyme called ligase

Question 9

where does DNA replication occur ?

Answer 9

• several locations on a DNA molecule

Question 10

name the stores of forming a lagging strand

Answer 10

FORMATION OF NEW STRAND

6. synthesis occurs in a 5’ to 3’ direction (on the new strand)
7. The DNA nucleotides will then bind to their complementary bases on the template strand

Question 11

name the steps of formation of new strand

Answer 11

FORMATION OF NEW STRAND

6. synthesis occurs in a 5’ to 3’ direction (on the new strand)
7. The DNA nucleotides will then bind to their complementary bases on the template strand