DNA replication (M1B1)

Question 1

what is DNA replication?

Answer 1

it is the synthesis of new DNA molecule

Question 2

when does DNA synthesis occur?

Answer 2

S phase

Question 3

what is semiconservative?

Answer 3

following replication, each daughter molecule of DNA contains 1 intact parental strand and 1 newly synthesized strand joined by base pairs

Question 4

what does bidirectional mean?

Answer 4

that replication begins at a site of origin and simultaneously moves out in both directions from that point

Question 5

DNA replication is both semiconservative and bidirectional

Answer 5

…

Question 6

prokaryotes have 1 origin of replication called?

Answer 6

oric

Question 7

eukaryotes have multiple replication origins

Answer 7

…

Question 8

• how many hydrogen bonds are holding AT together?

- how many hydrogen bonds are holding GC together?

Answer 8

• 2

- 3

Question 9

AT are easier to separate than GC cuz?

Answer 9

their melting point is less

Question 10

what are the 5 steps of replication?

Answer 10

1) unwinding
2) formation of RNA primer
3) synthesis of new DNA strands
4) excision of RNA primer and their replacement with DNA
5) proof reading n editing

UFSEP

Question 11

where does unwinding occur and what does it create?

Answer 11

origin of replication, 2 replication forks (group of proteins responsible for separation of DNA strands)

Question 12

an enzyme that separates the 2 strands of DNA by cleaving (splitting) the hydrogen bonds is called?

Answer 12

DNA Helicase

Question 13

proteins that hold the separated strands how from each other created by helicase so they don’t foil again are called?

Answer 13

single-strand binding proteins (SSBP)

Question 14

the local unwinding in one region leads to super coiling in front of the separated part which prevents?

Answer 14

further separation of the helix

Question 15

enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule?

Answer 15

DNA polymerase

Question 16

what release the super coils by transient cutting of the phosphodiester bonds in 1 or 2 strands of DNA?

Answer 16

tropoisomerases

Question 17

what are the types of tropoisomerases and the function?

Answer 17

• tropoisomerases 1: it can make transient cut in 1 DNA strand. doesn’t require energy
• tropoisomerases 2: it can make transient citizens both DNA strands. requires ATP for energy.

Question 18

clinically chemicals that inhibit tropoisomerases in humans are in? while the ones that inhibit prokaryotes are used as?

Answer 18

• chemotherapy ex. etoposide

- antibiotic ex. quinolone

Question 19

the enzyme that synthesizes DNA cannot initiate replication it needs a……….?

Answer 19

primer

Question 20

enzyme that creates the primer is called?

Answer 20

primase

Question 21

RNA primer is a short fragment of RNA (about 10 nucleotides)

Answer 21

…

Question 22

RNA primer needs what enzyme for its synthesis in 5’-3’ direction?

Answer 22

primase enzyme

Question 23

RNA primer is removed later on for the other DNA strand to bind

Answer 23

…

Question 24

DNA polymerase are also called?

Answer 24

DNA dependent DNA polymerase

Question 25

why is DNA dependent DNA polymerase called that?

Answer 25

cuz it DNA polymerase synthesis new dna strand depending on the templet which is DNA

Question 26

how many types are there of DNA polymerase

Answer 26

5

(they are a group of enzymes responsible for adding complementary deoxynucleotides to 3’OH and of pre-existing nucleotide)

Question 26

dna polymerase can only synthesis in 1 direction which is?

Answer 26

5’ to 3’ direction

Question 28

when the new strand joins the old strand a phosphodiester bond forms between adjacent nucleotides (AT GC)

Answer 28

…

Question 29

each precursor pairs with the complete add on the template strand and forms a phosphodiester bond with 3’hydroxyl end of the growing chain with the release of?

Answer 29

pyrophosphate

Question 30

DNA polymerase catalyze the synthesis of DNA, they are called?

Answer 30

DNA dependent DNA polymerase

Question 31

how many eukaryote types of DNA polymerase are there?

Answer 31

5

Question 32

what is DNA-dependent DNA polymerases responsible for?

Answer 32

adding complementary deoxynucleotides to 3’OH end of preexisting nucleotide and RNA primer (cannot initiate DNA synthesis)

Question 34

• leading strand moves in what direction?

- lagging strand moves in what direction?

Answer 34

• 3’-5’ direction (same as the replication fork)

- 5’-3’ (opp. the replication fork)

Question 35

in the leading strand there is only need of 1 RNA primer to synthesis following the replication fork aka CONTINUOUS while in the lagging strand needs another RNA primers to synthesis moving the opposite direction aka DISCONTINUOUS

Answer 35

…

Question 36

The leading strand extended from one primer alone, the lagging strand needs a new primer for each of the short okazaki fragments

Answer 36

…

Question 37

okazaki fragments are only present on?

Answer 37

lagging strands (each piece had its RNA primer

Question 38

when the rna primer is done what excises it off?

Answer 38

RNase H

Question 39

gaps resulted from excised RNA primer are filled by?

Answer 39

deoxyribonucleotides (with help of DNA polymerase)

Question 40

An enzyme that catalyses formation of Phosphodiester Bonds between two polynucleotide chains And joins DNA fragments together is called?

Answer 40

DNA ligase (needs ATP)

Question 41

many of the antiviral drugs used in the treatment of HIV are analogs of?

Answer 41

deoxyribonucleoside triphosphates

ex. the drug zidovudine that contains thymidine that lacks 3’-hydroxyl. which interferes in the growth and multiplication of virus causing its death