DNA Structure and Synthesis COPY COPY Flashcards

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1
Q

Describe transformation

A

when one bacteria changes the characteristics of another

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2
Q

How did transformation lead to the discovery of DNA?

A

It was discovered that DNA was the transforming factor

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3
Q

What is a bacteriophage?

A

a virus that uses a bacteria to replicate itself

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4
Q

How did bacteriophage help confirm the role of DNA?

A

the virus injects DNA into the bacteria to replicate itself which showed that DNA stored genetic information

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5
Q

What is X-ray crystallography?

A

early technique used to get a visual of DNA

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6
Q

How does X-ray crystallography work?

A

it diffracts light through a DNA crystal which creates an image

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7
Q

Describe DNA structure

A

double helix which runs anti-parallel

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8
Q

Describe double helix

A

two strands twisted around each other

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9
Q

Describe anti-parallel

A

3’ and 5’ ends run opposite directions

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10
Q

What makes up a nucleotide

A

base, sugar, phosphate

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11
Q

What makes up a nucleoside

A

base, sugar

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12
Q

Pyrimidines have ___ ring (s)

A

one

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13
Q

Purines have ___ ring (s)

A

two

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14
Q

Pyrimidines consist of what bases?

A

cytosine, thymine, uracil

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15
Q

Purines consist of what bases?

A

adenine, guanine

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16
Q

What do Chargaff’s rules state

A

in any species there is an equal number of A and T bases, and an equal number of G and C bases

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17
Q

Purine + purine would impact the DNA structure how?

A

too wide

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18
Q

Pyrimidine + pyrimidine would impact the DNA structure how?

A

too narrow

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19
Q

What is the correct model of DNA replication?

A

semiconservative model

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20
Q

Describe the semiconservative model

A

replicated DNA will have one old and one new strand of DNA

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21
Q

Describe the conservative model

A

the two parent strands rejoin

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22
Q

Describe the dispersive model

A

each strand is a mix of old and new

23
Q

Describe origins of replication

A

where the two DNA strands are separated forming a “bubble”.

24
Q

Describe the replication fork

A

the ends of the bubble where new DNA strands begin elongating.

25
Q

Bacterial DNA is what shape?

A

circular

26
Q

Describe helicases

A

enzymes that untwist the double helix at the replication forks

27
Q

Describe topoisomerase

A

goes ahead of replication forks, cuts, unwinds, and rejoins DNA strands

28
Q

Why is topoisomerase needed?

A

to keep the DNA strands from being too twisted

29
Q

Describe single-strand binding protein

A

holds the DNA strand straight so it can be used as a template

30
Q

What is a primer

A

a short strand of RNA that is laid down at the origin of replication

31
Q

What is primase?

A

enzyme that lays down the primer

32
Q

Describe DNA Polymerase III

A

adds DNA nucleotides to the 3’ end of the primer

33
Q

The new strands grow in ________ directions.

A

opposite

34
Q

DNA polymerases add nucleotides only to the __ ___of a strand

A

3’ end

35
Q

a new DNA strand can elongate only in the __ to __ direction

A

5’ to 3’

36
Q

Leading strand grows _______the origin of replication

A

in front of

37
Q

Lagging strand grows _______ of the origin of replication

A

behind

38
Q

Describe Okazaki fragments

A

a series of primers and new DNA segments

39
Q

Describe DNA polymerase I

A

removes the RNA primers and replaces them with DNA nucleotides

40
Q

Describe DNA ligase

A

connects the new DNA nucleotides

41
Q

___ ___________ proofread DNA as it is added

A

DNA Polymerases

42
Q

________ can repair __________ based pairs or ________ DNA

A

enzymes; mismatched; damaged

43
Q

Describe nucleotide excision repair.

A

cutting out damaged DNA and replacing it with new DNA

44
Q

Describe nuclease

A

an enzyme that cuts out damaged DNA

45
Q

In nucleotide excision repair, what happens after DNA is cut out?

A
  1. DNA Polymerase adds new nucleotides

2. Ligase seals the new nucleotides

46
Q

Why is DNA cut short after every replication?

A

DNA can’t be added to 5’ end new strands

47
Q

How is DNA code protected from being cut?

A

meaningless code protects the real code

48
Q

Describe telomeres

A

repetitive nucleotide sequences at the end of DNA that do not contain genes

49
Q

Describe telomerase

A

an enzyme that lengthens telomeres in gamete DNA

50
Q

Why is telomerase needed?

A

so a zygote can start off with a full set of telomeres

51
Q

Describe histones

A

DNA wrapped around bead like proteins

52
Q

Describe chromatin

A

DNA and histones together

53
Q

What happens into DNA packaging after histones are made?

A

the Chromatin is coiled together into a larger fiber