Introduction to DNA replication

Question 1

Watson and Crick 1953

Answer 1

In a second replication April 1953, they outlined a model for DNA replication later called semi-conservative replication which explained the use of both DNA strands as templates for the synthesis of new strand with the bases on the template strand dictating the new daughter straps

Question 2

between 1953 and 1957

Answer 2

before the Melselon-Stahl experiment verified stem-conservative replication of DNA

Question 3

One of the most famous statements in molecular biology

Answer 3

“It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material” 1953

Question 4

What is DNA replication

Answer 4

a molecular process in which genomic DNA is copied in cells before it divides and therefore must

Question 5

The prices of DNA replication involves

Answer 5

copying billions of nucleotides and therefore must be carried out with speed and accuracy

Question 6

DNA double helix contains

Answer 6

a sequence of nucleotides that is exactly complementary to nucleotide sequence of partner strand (base-pairing)

Question 7

During DNA replication

Answer 7

2 strands separate and each separated strand serves as template for production of a new complementary strand (by base-pairing)

Question 8

Dna replication is a

Answer 8

semi-conservative process because each of 2 newly copied daughter DNA molecules will have 1 old ‘parent’ strand (original template) and 1 newly made strand

Question 9

replication machine

Answer 9

DNA replication is carried out by groups of proteins and enzymes

Question 10

Basic concept of DNA replication (a)

Answer 10

The parent molecules two complementary strands of DNA. Each base is paired by hydrogen bonding with its specific partner, A with t and G with C

Question 11

Basic concept of DNA replication (b)

Answer 11

The first step in replication is separation of the two DNA strands

Question 12

Basic concept of DNA replication (c)

Answer 12

Each parental strand now serves as a template that determines the order of nucleotides along a new, complementary strand

Question 13

Basic concept of DNA replication (d)

Answer 13

The nucleotides are connected to form the sugar-phosphate back-bones of the new strands. Each “daughter” DNA molecule consists of one parental strand and one new strand

Question 14

Origin of replication

Answer 14

1. Replication of DNA begins at special sites called origins of replication (ori) marked by particular sequence of nucleotides usually A-T rich (rich in A-T base pairs are slightly weaker so that helixes can open the a little easier)
2. Elongating a new DNA strand, involves incorporating a new nucleotide into the strand using nucleotides that attach their partner (base pair) on the template strand, this occurs at the replication fork where enzymes known as DNA polymerases catalyse the addition of new nucleotides to the new strand at the 3’ end

Question 15

DNA needs to

Answer 15

copy every base before it can divide

Question 16

Bacterial genome

Answer 16

1 single origin of replication (smaller so it only needs one)

Question 17

Human genome

Answer 17

10,000 origins of replication

Question 18

Proteins that initiate DNA replication

Answer 18

attach to DNA at origin of replication and separate 2 strands opening up a replication “bubble”

Question 19

Replication proceeds in both directions

Answer 19

from each origin until entire molecule is copied

Question 20

At each end of the replication bubble

Answer 20

is a replication fork: a Y-shaped region where new strands of DNA are elongated

Question 21

DNA replication is bidirectional

Answer 21

2 replication forks move away from the organ in both directions

Question 22

5’

Answer 22

has a phosphate attached