DNA Replication- PowerPoint

Question 1

What is the template strand?

Answer 1

parent strand, what the daughter strand replicates from

Question 2

What is the daughter strand?

Answer 2

new strand

Question 3

Watson and Crick proposed what type of model?

Answer 3

semi-conservative model

Question 4

What is the Conservative replication model?

Answer 4

The two strands of the original molecule serve as templates for the two strands of a new DNA molecule; then, they rewind into an all “old” molecule.

Question 5

What is a the Dispersive replication model?

Answer 5

Neither parental strand is conserved, and both chains of each replicated molecule contain old and new segments.

Question 6

What is semi-conservative model?

Answer 6

2 daughter stands both have a parent strand for first round of replication

Question 7

Which mode of replication would require the most amount of energy?

Answer 7

dispersive model

Question 8

Which mode of replication does DNA actually follow?

Answer 8

semi-conservative model

Question 9

What happened in Meselson and Stahl experiment?

Answer 9

• Bacterial cells were grown in a heavy isotope of nitrogen, 15N
• All the DNA incorporated 15N
• Cells were switched to media containing lighter 14N
• DNA was extracted from the cells at various time intervals
• DNA Molecules with different densities were separated by centrifugation

Question 10

How did they band the density gradient in Meselson and Stahl experiment?

Answer 10

cesium chloride

Question 11

Something with a higher density will band where?

Answer 11

bottom of tube

Question 12

Where were the location of the 15N and 14N in the tube?

Answer 12

15N on bottom bc higher density and 14N in the top of the tube

Question 13

How does the density gradient separate a sample?

Answer 13

the sample will band with the density band that matches it

Question 14

How long does it take for a bacteria to replicate? (binary fission)

Answer 14

20 minutes

Question 15

What do the peaks correspond to?

Answer 15

the number of bands

Question 16

During the first round where the sample had 0 rounds of replication what nitrogen was found in it?

Answer 16

15N

Question 17

During the first round where the sample had 1 rounds of replication what nitrogen was found in it?

Answer 17

15N and 14N

Question 18

During the first round where the sample had 2 rounds of replication what nitrogen was found in it?

Answer 18

15N and 14N hybrid and a pure 14N

Question 19

DNA with 15N and 14N will have what type of density?

Answer 19

hybrid

Question 20

Which replication models did the first sample where 0 rounds of replication occurred?

Answer 20

all

Question 21

Which replication models did the second sample where 1 rounds of replication occurred?

Answer 21

semi-conservative and dispersive

Question 22

Which replication models did the third sample where 2 rounds of replication occurred?

Answer 22

only semi-conservative

Question 23

What are DNA polymerases?

Answer 23

assemble complementary polynucleotide chains from

individual deoxyribonucleotides

Question 24

What are the 4 deoxyribonucleotide triphosphates?

Answer 24

dATP, dGTP, dCTP, and dTTP

Question 25

Where does DNA polymerases add nucleotides?

Answer 25

only to the 3′ end of an existing chain

Question 26

What are the rules of DNA polymerase? (3)

Answer 26

1) 5' -----> 3' 2) nucleotides added to 3' end 3) new and old strand are anti-parallel

Question 27

What provides energy for DNA chain elongation reaction?

Answer 27

hydrolysis of Pyrophosphate

Question 28

What do they use for banding densities now?

Answer 28

sucrose

Question 29

What is the gel that DNA is run on?

Answer 29

auger gel

Question 30

How long does the auger gel need to solidify?

Answer 30

10 mins

Question 31

What is used for intercalation (inbetween) between base pairs?

Answer 31

ethridium bromide

Question 32

How do you see the DNA after you have run the gel?

Answer 32

UV light

Question 33

What does ethridium bromide color the DNA?

Answer 33

pink

Question 34

What is used to make wells in the gel?

Answer 34

comb

Question 35

If one sample has 80 base pairs and the other sample has 120 base pairs which sample moves faster in the sample?

Answer 35

80 base pair sample

Question 36

What is the control in the gel?

Answer 36

molecular weight marker

Question 37

How many base pairs is 1kb?

Answer 37

1000kb

Question 38

What 3 things does DNA replication require?

Answer 38

1) Parental DNA molecule---template 2) Enzymes – DNA Polymerases 3) Nucleotide triphosphates – four different dATP, dTTP, dCTP, and dGTP

Question 39

What do DNA polymerases assemble?

Answer 39

complementary polynucleotide chains from individual | deoxyribonucleotides

Question 40

What is a sliding clamp and what is its shape?

Answer 40

protein, doubt shape

Question 41

Is the sliding clamp behind or ahead of the DNA polymerase?

Answer 41

behind

Question 42

Whats the role of the sliding clamp?

Answer 42

make sure DNA polymerase doesn't fall off the template strand

Question 43

What is the result of the sliding clamp?

Answer 43

increases efficiency

Question 44

How is the sliding clamp loaded and unloaded onto replicating DNA in humans?

Answer 44

clamp loader, The efficient unloading of sliding clamps by clamp loaders once DNA polymerase has dissociated from DNA is probably important for the overall efficiency of DNA replication

Question 45

How does a new strand of DNA begin if there is no existing chain?

Answer 45

A new strand begins with a short chain of RNA (primer), synthesized by the enzyme primase

Question 46

What does primase do?

Answer 46

Primase leaves the template, and DNA polymerase takes over, extending the RNA primer with DNA nucleotides as it synthesizes the new DNA chain

Question 47

What are RNA primers are replaced with later in replication?

Answer 47

DNA

Question 48

What is ori? and what happens?

Answer 48

origin of replication, In the bacterial chromosome, unwinding of DNA for replication occurs here bidirectionally

Question 49

What unwinds DNA?

Answer 49

DNA helicase

Question 50

What does DNA helicase produce?

Answer 50

Y-shaped replication fork

Question 51

What do Single-stranded binding proteins (SSBs) do?

Answer 51

coat the exposed single-stranded DNA segments, keeping them from pairing.

Question 52

What does Topoisomerase do?

Answer 52

cuts and rejoins DNA to prevent twisting in circular | bacterial chromosomes.

Question 53

What direction is the template strand read in?

Answer 53

3′→5′ direction

Question 54

What is torsional strain?

Answer 54

the strain caused by the twisting of DNA

Question 55

What relieves torsional strain?

Answer 55

topoisomerase

Question 56

What does DNA helicase get its energy from?

Answer 56

ATP hydrolysis

Question 57

What is a leading strand?

Answer 57

the new DNA strand is synthesized in the direction of DNA unwinding. This is a single priming event.

Question 58

Which strand is Synthesized on the leading strand template?

Answer 58

leading strand

Question 59

What is the lagging strand?

Answer 59

strand synthesized discontinuously in the direction opposite DNA unwinding

Question 60

How many priming events does the leading strand need?

Answer 60

1

Question 61

How many priming events does the lagging strand need?

Answer 61

multiple

Question 62

Which strand is Synthesized on the lagging strand template?

Answer 62

lagging stand

Question 63

What are Okazaki fragments? how long are they?

Answer 63

fragments of DNA, 100 – 200 base pairs long

Question 64

Which strand replicates away from the fork?

Answer 64

lagging strand

Question 65

Which strand replicates towards the fork?

Answer 65

leading strand