DNA Replication

Question 1

Watson and Crick’s model of DNA allowed for replication, and thus transfer of genetic information.

1. Conservative
2. Semiconservative
3. Dispersive

Answer 1

Replication Models

Question 2

One parent double helix and one new double helix

Answer 2

Conservative Model

Question 3

One strand is from the parent and one is the novel strand from the new molecules, forming the double helix

Answer 3

Semiconservative Model

Question 4

Amounts of the parent strand are dispersed in the novel strand, forming a mixed double helix

Answer 4

Dispersive Model

Question 5

• DNA polymerase
• Helicase
• Ligase
• dNTP
• Primers
• Primase
• Protein binding complex
• Topoisomerase
• Telomerase
• SSb
• Okazaki fragments

Answer 5

Molecules involved in replication

Question 6

Catalyzes phosphodiester bond formation

-polymerization of dNTPs,

Answer 6

DNA polymerase

Question 7

Breaks hydrogen bonds between the nitrogenous bases

“unzips genes”

Answer 7

Helicase

Question 8

Connects DNA strands

Answer 8

Ligase

Question 9

deoxynucleosidetriphosphate

-“nucleotide”

Answer 9

dNTP

Question 10

RNA fragments

Answer 10

Primer

Question 11

Synthesizes the RNA primer

-Can only add nucleotides to the existing strand of DNA.

Answer 11

Primase

Question 12

Untwist DNA to relieve pressure ahead of replication fork

Answer 12

Topoisomerase

Question 13

Synthesizes telomeres

Answer 13

Telomerase

Question 14

Single stranded binding protein

stabilize newly single stranded regions

Answer 14

SSb

Question 15

Discontinuous lagging strand

Answer 15

Okazaki Fragments

Question 16

1. Replicator sequence is denatured by initiator proteins to form a replication bubble
   - new strand is made in accordance with complementary basepairing rules
2. Helicase loaded onto the DNA
   - breaks H bonds, requires ATP
3. Helicase recruits Primase
   - change in shape when helicase binds to DNA is recognized by Primase
4. Primase synthesizes a short primer
   - RNA: 5-10 nucleotides long, annealed to template DNA strand according to complementary base pairing rules

Answer 16

Initiation of Replication Process

Question 17

4. SSB proteins bind to the single stranded DNA
5. Polymerase III adds nucleotides ONLY in the 5’ to 3’ direction
6. DNA gyrase relaxes the tension ahead of the replication fork
7. Polymerase I activity
8. DNA ligase activity

Answer 17

Semidiscontinuous Replication

Question 18

Displaced by polymerase prevents reannealing

Answer 18

SSB proteins binding to the single stranded DNA in the fork

Question 19

• synthesizes off of RNA primer for both leading & lagging strand
• catalyzes 5’ to 3’ polymerization of dNTPs
• reads template 3’ to 5’

Answer 19

DNA Polymerase III

Question 20

Synthesis from 5’ to 3’ direction

Answer 20

All polymerases synthesize this way

Question 21

-Introduces supercoiling in order to relieve stress

Answer 21

DNA Gyrase

Question 22

• Joining of the Okazaki fragments
• Digests RNA primer ahead of it using its 5’ to 3’ exonuclease activity.
• Replaces RNA primer with dNTPs using its 5’ to 3’ polymerase activity

Answer 22

DNA Polymerase I

Question 23

Degrades sequence at the ends

Answer 23

Exonucleases

Question 24

• Joining of Okazaki Fragments

- Seals the nick between adjacent fragments

Answer 24

DNA Ligase

Question 25

All known DNA polymerases: a. can initiate DNA chain synthesis b. have 5' to 3' polymerization activity c. have 5' to 3' exonuclease activity d. have 3' to 5' polymerization activity e. all of the above

Answer 25

b. have 5' to 3' polymerization activity

Question 26

What is the primer for DNA pol. I? a. RNA synthesized by primase b. DNA synthesized by primase c. Okazaki fragment d. It doesn't need a primer

Answer 26

c. Okazaki fragment

Question 27

Accuracy of polymerase

Answer 27

Fidelity

Question 28

How long DNA polymerase can stay on the strand

Answer 28

Procesicivity

Question 29

- More mistakes to correct, less time to add nucleotides | - Almost always adds the correct complementary bp.

Answer 29

Polymerase's proofreading activity

Question 30

Have 3' to 5' exonuclease activity

Answer 30

Both DNA Pol. I and DNA Pol. III

Question 31

Remove incorrect 3' nucleotide, insert correct base, and keep synthesizing

Answer 31

DNA Polymerase

Question 32

DNA Polymerase ______ has 5' to 3' and 3' to 5' exonuclease activity. a. I b. III

Answer 32

a. I - only DNA Pol. I will chew up Okazaki primer.

Question 33

- a complex molecular machine that carries out replication of DNA. - first unwinds double stranded DNA into two single strands. - For each of the resulting single strands, a new complementary sequence of DNA is synthesized.

Answer 33

The Replisome

Question 34

-Replication process similar to prokaryotes, but chromosomes are bigger and linear -Contains multiple origins per chromosome ex. autonomously replicating sequences in yeast. -15 polymerases not all participate in replication, many participate in DNA repair -DNA is packed as it is synthesized

Answer 34

DNA Replication in Eukaryotes

Question 35

Area where one origin of replication to where 2 origins of replication fuse

Answer 35

Replicon

Question 36

Multiple Origins: Many start at the same time

Answer 36

Replication in Eukaryotes

Question 37

- Tandemly repeated | - added by enzyme telomerase

Answer 37

Telomeres

Question 38

Is a reverse transcriptase | complex of protein (does the synthesizing) and RNA (template)

Answer 38

Telomerase

Question 39

Makes DNA from RNA template

Answer 39

Reverse transcriptase

Question 40

Telomerase_____ a. contains its own RNA template b. is a reverse transcriptase c. extends one strand of the telomere d. is responsible for helping to maintain chromosome size e. all of the above are true

Answer 40

e. all of the above are true

Question 41

Type of supercoiling that relieves stress | Think of DNA Gyrase and what it does

Answer 41

Positive supercoiling