Topic 6.2 - Replication

Question 1

what does DNA replication ensure?

Answer 1

ensures the continuity of hereditary information

Question 2

what happens during DNA replication?

Answer 2

genetic information is copied

Question 3

when does DNA replication occur?

Answer 3

before cell division

Question 4

What does DNA replication allow?

Answer 4

allows transmission of a complete genome from one generation to the next

Question 5

how is the continuity of hereditary information ensured?

Answer 5

through specific replication mechanisms

Question 6

is DNA replication semiconservative?

Answer 6

yes

Question 7

what does semiconservative replication result in?

Answer 7

results in a DNA molecule containing one original strand and a newly synthesized complimentary strand

Question 8

what is the purpose of the original strand?

Answer 8

each original strand serves as a template for the synthesis of a new complimentary strand

Question 9

what does directionality in a DNA molecule influence?

Answer 9

the replication process

Question 10

what is on each end of a DNA strand?

Answer 10

each strand has a terminal phosphate group and a terminal hydroxyl end

Question 11

what is each end labelled as?

Answer 11

> phosphate terminus: 5’ end
hydroxyl terminus: 3’ end

Question 12

how do these ends run?

Answer 12

antiparallel to each other

Question 13

how are nucleotides added?

Answer 13

nucleotides can only be added to a growing strand in the 5’-3’ direction

Question 14

leading strand

Answer 14

the strand that will be synthesized continuously

Question 15

lagging strand

Answer 15

the strand that will be synthesized discontinuously (in fragments)

Question 16

what are involved in DNA replication?

Answer 16

enzymes

Question 17

what is the purpose of helicase?

Answer 17

unwinds the DNA strands (takes HELIX of DNA and untwists it)

Question 18

what is the purpose of topoisomerase?

Answer 18

to relax the supercoil at the replication fork

Question 19

replication fork

Answer 19

the location where the two strands are separated

Question 20

what is the purpose of DNA polymerase? what does it require?

Answer 20

synthesizes new strands but requires RNA primers to initiate synthesis

Question 21

how does the RNA primer work?

Answer 21

it attaches to the 3’ end of the template strand and builds strands in a 5’-3’ direction

Question 22

what is the purpose of ligase?

Answer 22

joins DNA fragments on the lagging strand

Question 23

what is the purpose of the single stranded binding proteins?

Answer 23

protect the separated DNA strands from cleavage and stabilize the strands, preventing them from rejoining

Question 24

what direction does the leading strand move in?

Answer 24

the same direction as the replication fork

Question 25

what enzyme is involved in DNA repair?

Answer 25

DNA polymerase I

Question 26

what enzyme is involved in proofreading?

Answer 26

DNA polymerase I and III

Question 27

RNA primase

Answer 27

enzyme that builds a small complimentary RNA segment on the strand at the beginning of the replication fork

Question 28

RNA primers

Answer 28

short RNA sequences that act as the starting point for replication