DNA Replication Flashcards

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1
Q

What is replication?

A

duplication of DNA

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2
Q

When does DNA replication occur?

A

S phase in interphase of the cell cycle

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3
Q

What does it mean for DNA replication to be semiconservative?

A

new daughter strands are synthesized using the parental DNA as a template to copy from; each new daughter strand is perfectly complementary to the parental strand

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4
Q

What is the helicase?

A

enzyme that unwinds, separates and stabilizes double stranded DNA

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5
Q

What is the place that helicase begins to unwind the DNA?

A

ORI; origin of replication

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6
Q

What protein in bacteria will find the ORI?

A

DnaA

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7
Q

What are topoisomerases?

A

enzymes that cut one or both double strands and unwrap the helix, releasing the excess tension caused by the helicase

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8
Q

What are SSBPs?

A

single-strand binding proteins; protect the DNA that has been unpackaged and help keep the strands separated

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9
Q

What is the open complex?

A

when the two strands are separated

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10
Q

What must occur prior to replication of DNA?

A

RNA primer must be synthesized for each template strand

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11
Q

What enzyme/proteins is involved in creating the RNA primer?

A

protein complex = primosome
enzyme = primase

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12
Q

What catalyzes the elongation of the daughter strand?

A

DNA polymerase

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13
Q

What complex is DNA polymerase a part of?

A

replisome

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14
Q

What is the thermodynamic driving force for polymerization reaction?

A

removal and hydrolysis of pyrophosphate from each dNTP added to the chain

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15
Q

Which direction does polymerization occur?

A

5’ to 3’

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16
Q

What is the replication fork?

A

areas where parental double helix continues to unwind

17
Q

What are leading strands?

A

strands that elongate continously into the widening replication forks

18
Q

What are lagging strands?

A

must wait until the replication fork widens before beginning polymerization

19
Q

What are Okazaki fragments?

A

small chunks of DNA comprising the lagging strand

20
Q

What are the two important DNA polymerases found in prokaryotes?

A

DNA Poly III
DNA Poly I

21
Q

What is the function of DNA poly III?

A

fast elongation of the leading strand; it has proofreading capabilities

22
Q

What is the function of DNA poly I?

A

starts at nucleotides at the RNA primer; has poor processivity

23
Q

What is the Hayflick limit?

A

number of times a normal human cell type can divide until telomere length stops cell division

24
Q

What is telomerase?

A

enzyme that adds repetitive sequences to the ends of chromosomes and lengthens telomeres

25
Q

What cells is telomerase expressed in?

A

germ line, embryonic stem cells, and white blood cells

26
Q

What enzyme is responsible for connecting the Okazaki fragments together?

A

DNA ligase

27
Q

What is exonuclease?

A

cutting a nucleic acid chain at the end

28
Q

What is endonuclease?

A

cutting a nucleic acid chain in the middle

29
Q

What are restriction enzymes?

A

endonucleases found in bacteria