Unit 1-KA2

Question 1

Describe the shape of a DNA molecule

Answer 1

double helix

Question 2

Describe how the two strands of DNA are held together

Answer 2

base pairs are held together by weak hydrogen bonds

Question 3

Name three components that make up a nucleotide

Answer 3

deoxyribose sugar
base
phosphate

Question 4

complementary base pairing

Answer 4

adenine and thymine

guanine and cytosine

Question 5

antiparallel

Answer 5

the two DNA strands run in opposite directions
5’ to 3’
3’ to 5’

Question 6

Describe the effect of the increase in temperature at step 1 on the structure of DNA

Answer 6

breaks hydrogen bonds and separates strands

Question 7

State the need for the reduction in temperature at step 2

Answer 7

allows primers to bind

Question 8

Explain why the DNA polymerase used in step 4 can function at 70°C, although the high temperature would denature most enzymes

Answer 8

heat tolerant DNA polymerase

Question 9

Uses of PCR

Answer 9

DNA profiling
Disease detection
Paternity Tests

Question 10

Research uses of PCR

Answer 10

drug development

disease development

Question 11

PCR

Answer 11

allows specif sections of DNA to be amplified in-vitro

Question 12

Why is replication important

Answer 12

cells need to copy their DNA prior to cell division
ensures new cells have the same-
number of chromosomes
genes

Question 13

Process of replication

Answer 13

DNA unwinds and separates strands
Primers bind to the 3’ end of the DNA template
DNA polymerase adds complementary DNA nucleotides
DNA polymerase can only add nucleotides in one direction resulting in-
leading strand-continuously
lagging strand-fragments
fragments are joined by ligase
ATP is required