Lesson 6 Flashcards

DNA Replication

1
Q

Deoxyribonucleic acid is made out of:

A

sugars (deoxyribose)
phosphates
nitrogen bases

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2
Q

Who discovered the DNA structure in 1953?

A

James Watson and Francis Crick

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3
Q

What is Chargoff’s Rule?

A

A=T
C=G

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4
Q

What are the four requirements for DNA to be a genetic material?

A
  • Must carry information
  • Must replicate
  • Must allow for information to change
  • Must govern the expression of the phenotype
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5
Q

DNA requirement that is cracking the genetic code

A

Carrying information

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6
Q

DNA requirement that replicates

A

DNA replication

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7
Q

DNA requirement for allowing information to change

A

Mutation

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8
Q

DNA requirement that govern the expression of the phenotype

A

Gene function

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9
Q

Where does DNA store information?

A

In the sequence of its bases

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10
Q

Much of DNA’s sequence of information is accessible only when:

A

The double helix is UNWOUND

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11
Q

When do proteins read the DNA sequence of nucleotides?

A

As the DNA helix unwinds

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12
Q

Can proteins bind to a DNA sequence or initiate the copying of it?

A

Both

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13
Q

How are some genetic information accessible even in intact?

A

In double-stranded molecules

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14
Q

How do some proteins recognize the base sequence of DNA without unwinding it?

A

with restriction enzymes

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15
Q

Three things that happens when cells divide:

A
  • growth
  • repair
  • replacement
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16
Q

Before cells divide, what happens to the cell structures, organelles and genetic information?

A

Double

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17
Q

DNA replication occurs with

A

great fidelity

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18
Q

Essential for DNA replication:

A
  • Somatic cell DNA stability
  • reproductive-cell DNA stability
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19
Q

What does stability have to do with DNA replication?

A
  • ensures identity
  • to avoid occurrence of genetic diseases
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20
Q

It is the process of duplication of the entire genome prior to cell division

A

DNA replication

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21
Q

The significance of DNA replication

A

Biological Significance

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22
Q

Why is extreme accuracy of DNA replication necessary?

A

In order to preserve the integrity of the genome in successive generations

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23
Q

When does replication occur in eukaryotes?

A

S phase

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24
Q

Replication rate in eukaryotes that results in a higher fidelity/accuracy of replication

A

slower

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25
Q

3 possible models of DNA replication

A
  • Semi-conservative
  • Conservative
  • Dispersive
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26
Q

Basic rules of DNA replication

A
  1. semi-conservative
  2. starts at the “origin”
  3. uni/bidirectional
  4. semi-discontinuous
  5. RNA primers required
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27
Q

One strand of duplex passed on unchanged to each of the daughter cells

A

Semi-conservative

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28
Q

Act as a template for the synthesis of a new, complementary strand by the enzyme DNA polymerase

A

“conserved” strand

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29
Q

Who demonstrated the semi-conservative model of DNA?

A

Meselson and Stahl

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30
Q

The initiator proteins that identify specific base sequences on DNA

A

sites of origin

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31
Q

Prokaryotes origin

A

single

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32
Q

Eukaryotes origin

A

multiple sites

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33
Q

The direction of synthesis is always

A

5’ - 3’

34
Q

In 5’-3’ direction, what are only added to the 3’ end of the growing strand?

A

nucleotides

35
Q

What part of the new nucleotide binds to the 3’-OH group of the last nucleotide of the growing strand?

A

5’-phosphate group

36
Q

In DNA replication, free nucleotides are added unto a _________ in a 5’ to 3’ direction taking energy for what bonds?

A

polynucleotide chain, phosphodiester bonds

37
Q

The energy needed for the phosphodiester bonds to form are generated

A

only one way

38
Q

Bonds that form between sugar and phosphate to form the backbone of nucleic acids for stability

A

Phosphodiester bonds

39
Q

Directions of DNA replication

A

Unidirectional & Bidirectional

40
Q

Process of DNA replication

A

semi-discontinuous replication

41
Q

Anti-parallel strands that replicate simultaneously

A

Leading strand & Lagging strand

42
Q

What strand synthesizes continuously in 5’-3’?

A

Leading

43
Q

What strand synthesizes in fragments in 5’-3’?

A

Lagging

44
Q

New strand synthesis is always in what direction?

A

5’-3’ direction

45
Q

DNA fragments in the Lagging strand

A

Okazaki fragments

46
Q

It is required short nucleic acid sequence that provides a starting point for DNA synthesis

A

RNA primer

47
Q

A primer must be synthesized before DNA replication can occur by what enzyme?

A

Primase

48
Q

A type of RNA polymerase that synthesizes a primer

A

primase

49
Q

What enzyme synthesizes DNA?

A

DNA polymerase

50
Q

DNA polymerase can only attach ___________ to an existing strand of nucleotides

A

new DNA nucleotides

51
Q

It serves to prime and foundation for DNA synthesis

A

primer

52
Q

Primers are ______ before DNA replication is complete

A

removed

53
Q

The gaps in the sequence are filled in with DNA by ___________

A

DNA polymerase

54
Q

Core proteins at the replication fork

A
  1. Topoisomerases
  2. Helicases
  3. Primase
  4. Single strand binding proteins
  5. DNA polymerase
  6. Tethering protein
  7. DNA ligase
55
Q

Prevents torsion by DNA breaks

A

Topoisomerase

56
Q

Separates 2 strands

A

Helicase

57
Q

RNA primer synthesis

A

Primase

58
Q

Prevent reannealing of single strands

A

Single strand binding protein

59
Q

Synthesis of new strand

A

DNA polymerase

60
Q

Stabilizes polymerase

A

Tethering protein

61
Q

Seals nick via phosphodiester linkage

A

DNA ligase

62
Q

What are the steps of Replication?

A
  1. Initiation
  2. Elongation
  3. Termination
63
Q

Proteins bind to DNA and open up the double helix and prepare DNA for complementary base pairing

A

Initiation

64
Q

Proteins connect the correct sequences of nucleotides into a continuous new strand of DNA

A

Elongation

65
Q

Proteins release the replication complex

A

Termination

66
Q

DNA replication usually proceeds in what direction

A

Bidirectionally

67
Q

DNA polymerase III adds nucleotidesin what direction

A

5’ - 3’ direction

68
Q

It removes the RNA primer and replaces it with DNA

A

DNA polymerase I

69
Q

They have 3’ to 5’ exonuclease activity

A

DNA polymerase I & DNA polymerase III

70
Q

What exonuclease activity is in 3’ to 5’?

A

Proofreading

71
Q

It has a 5’ to 3’ exonuclease activity

A

DNA polymerase I

72
Q

What exonuclease activity is in 5’ to 3’?

A

DNA repair

73
Q

It is preparing the double helix for use as a template

A

Initiation

74
Q

Relieves the strain ahead of the replication fork

A

DNA gyrase

75
Q

Linkage of subunits through the formation of phosphodiester bonds

A

Polymerization

76
Q

What does a DNA polymerase III first joins?

A

Correctly paired nucleotides to 3’ end of the growing chain

77
Q

When must the last primer sequence be removed from the end of the lagging strand?

A

During termination

78
Q

What do you call the last portion of the lagging strand containing a repeating non-coding sequence of bases?

A

The telomere section

79
Q

What leads to shorter strands after each cycle?

A

Enzymes snip off each a telomere at the end of each replication

80
Q

Enzymes that proofread the new double helix structures and remove mispaired bases

A

Nucleases

81
Q

It fills in the gaps created by the excised bases

A

DNA polymerase