8b

Question 1

Define dna replication?

Answer 1

process by which DNA is duplicated, DNA—>DNA

Question 2

Name the 3 possible mechanisms of dna replication

Answer 2

semiconstructive mechanism
conservative mechanism
dispersive mechanism

Question 3

define semiconstructive mechanism

Answer 3

dna replication produces 1 with parental strand and 1 newly made strand.

Question 4

define conservative mechanism

Answer 4

1 double helix with both parental strands and 1 with 2 new daughter strands

Question 5

define dispersion mechanism

Answer 5

dna strands in which segments of new dna+parental dna are present 🧬

Question 6

_______Showed that DNA Replication is semi-conservative.

Answer 6

Meselson and stahl experiment

Question 7

what is the molecular process of semi conservative replication

Answer 7

1.untwisting of dna molecule-both the strands as templates
2.DNA polymerase help to link free nucleotides to form new strands.
3.new and old template antiparallel

Question 8

untwisting of dna molecule?

Answer 8

Helicase, breaking the H bonds between nitrogenous bases

Question 9

after dna is divided into 2, each of the
2 strands are called_________

Answer 9

template

Question 10

what helps in the linking of nucleotide to form a new strand?

Answer 10

DNA polymerase

Question 11

the nucleotides are always added at what end?

Answer 11

3’- end, has a free OH group

Question 12

the nucleotides are connected to form the _______ of the new strands.

Answer 12

sugar-phosphate back bone

Question 13

replication fork

Answer 13

very active area where dna replication takes place

Question 14

topoisomerase?

Answer 14

avoid twisting of the DNA ahead of the replication fork by cutting the DNA, turning the DNA on side of the break in direction opposite to that of the twisting force and rejoining the twisting strand.

Question 15

____________ stabilizes single stranded DNA and prevent the 2 strands at __________ from reforming ______.

Answer 15

single-stranded binding proteins
replication fork
double stranded DNA

Question 16

function of primase?

Answer 16

assembles RNA primers in the 5’ to 3’ direction to initiate a new DNA strand

Question 17

what is the function of sliding clamp?

Answer 17

attaches DNA polymerase III to the DNA template, making replication more efficient

Question 18

which is the main replication enzyme in E. coli?

Answer 18

DNA polymerase III

Question 19

function of DNA polymerase III

Answer 19

extends the RNA primer by adding DNA nucleotides to it, synthesize new DNA strands during replication

Question 20

function of DNA polymerase I

Answer 20

removing RNA primers and replacing them with DNA nucleotides

Question 21

what is responsible for synthesizing Okazaki fragments?

Answer 21

dna polymerase III

Question 22

tell 4 uses of dna polymerase 1?

Answer 22

1.primer removing and gap filling
2.exonuclease activity from 5’to3’ and 3’to5’.
3.nick sealing (dna ligation)

Question 23

define primer removing?

Answer 23

dna polymerase I removing the RNA primers and adding dna nucleotides, aka primer removal and gap filling

Answer 24

DNA ligase functions to seal nicks and gaps in the adjacent bases by catalyzing the formation of phosphodiester bonds after RNA primers replaced with dna. Its main roles include joining Okazaki fragments during DNA replication, repairing DNA damage, and facilitating recombination events.

Question 25

what are Okazaki fragments

Answer 25

short, discontinuous DNA segments synthesized on the lagging strand , subsequently joined by DNA ligase to form a complete and continuous complementary strand.

Question 26

__________ joins short, discontinuous DNA segments to form a continous complementary strand?

Answer 26

DNA ligase

Question 27

________ have a single origin.

Answer 27

bacteria

Question 28

what is the rate of replication in bacteria as well as eukaryotes?

Answer 28

bacteria:500-1000 nucleotides per second eukaryotes:50-100 per second