1.11. DNA replication

Question 1

DNA stores ___ (___ ___) which are…

Answer 1

genes, genetic information, sections of DNA (on one strand only) with specific base sequence.

Question 2

DNA polymerization always happens in ____ direction.

Answer 2

5’ to 3’

Question 3

leading strand template

Answer 3

the original DNA strand which gets polymerized instantly as it unwinds - from down to up direction (5’ to 3’)

Question 4

lagging strand template

Answer 4

the original DNA strand which gets polymerized in fragments - use Okazaki fragments in the process of polymerization

Question 5

why is DNA replicated

Answer 5

to produce two identical copies of it and provide them to daughter cells in cell division

Question 6

semi-conservative model of DNA replication

Answer 6

each of the two copies of the DNA contain one strand of the original DNA

Question 7

the free-floating DNA/RNA nucleotides are found in ___ in prokaryotes and in ___ in eukaryotes.

Answer 7

nucleoid, nucleoplasm

Question 8

prokaryote DNA

Answer 8

• circular/ring -shaped
• only one point of origin or replication (helicate attaches to only 1 point)
  (P have only one chromosome and it’s small)

Question 9

eukaryote DNA

Answer 9

• linear (has beginning and end)
• helicase attaches to multiple points - several origin points
  (E have more and bigger chromosomes/longer DNA than P - speeding up the process)

Question 10

replication fork

Answer 10

site until where helicase has split the parental DNA

Question 11

DNA synthesis may occur…

Answer 11

…bi-directionally from the origin.

Question 12

DNA polymerization is ___ by short RNA sequences that are called…

Answer 12

initiated/primed, RNA primers

Question 13

why are RNA primers necessary

Answer 13

because DNA polymerize III can only join a nucleotide when there is an already existing, free 3’ end to attach it to and enzyme primase which attaches RNA (primase) does not have this limitation (more primitive)

Question 14

unlike connected nucleotides, free-floating have…

Answer 14

3 phosphate groups - when they join with other nucleotides the 2 extra groups detach and by doing that provide energy for the formation of the phosphodiester bond (3’-5’ linkage)

Question 15

free nucleotide with A N-base
free nucleotide with G N-base
free nucleotide with T N-base
free nucleotide with C N-base
together they are all called:

Answer 15

deoxyriboadenosine triphosphate
deoxyriboguanosine triphosphate
deoxyribotimosine triphosphate
deoxyribocytosine triphosphate
deoxyribonucleoside triphosphate

Question 16

ATP (adenosine triphosphate) is free…

Answer 16

deoxyriboadenosine

Question 17

how do ATP->ADP->AMP reactions release energy

Answer 17

by detaching their phosphate groups

Question 18

deoxyribonucleoside triphosphate =

Answer 18

N-base + deoxyribose + 3PO^3-

Question 19

other name for RNA nucleotides

Answer 19

ribonucleoside triphosphates

Question 20

enzymes involved in DNA polymerization

Answer 20

• helicase
• primase
• DNA polymerize III
• DNA polymerize I
• gyrase
• ligase
• single-strand binding proteins

Question 21

function of gyrase

Answer 21

also called topoisomerase - relieves the pressure from the super-condensed upper part of the DNA by unwinding the DNA from above (opposite direction from helicase)

Question 22

function of single strand binding proteins

Answer 22

keeping the newly separated DNA strands from coming back together due to attraction forces between their complimentary N-bases

Question 23

6 steps of DNA polymerization

Answer 23

1| helicase unzips and unwinds the existing DNA by breaking H-bonds between complimentary N-bases of the two strands
2| free RNA nucleotides in the nucleoplasm/nucleoid attach themselves to the now free N-bases on the separated DNA strands
3| primase connects the two RNA primers by creating a phosphodiester bond between them
4| DNA polymerize III attaches free DNA nucleotides to the next free N-bases and forms 3’-5’ linkages between DNA segments and bordering DNA and RNA nucleotides
5| DNA polymerize I digests the RNA primers
6| ligase creates phosphodiester bonds between the two separated parts of the new strand (fills in the gaps)