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Foundations 1 > DNA Replication and Repair > Flashcards

DNA Replication and Repair Flashcards

1
Q

What is chromatin?

A

DNA
Histones
Non-histone proteins

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2
Q

What are the types of histones and their functions?

A

H1 - links
Cores: H2A, H2B, H3, H4

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3
Q

What is a nucleosome?

A

Basic unit of DNA organization around histone octomer

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4
Q

What is a histone octomer?

A

Two of each of the 4 core histones

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5
Q

What is the interphase chromosome?

A

Nucleosomes arranged for transcription, replication and repair

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6
Q

What is the mitotic chromosome?

A

Chromatin is condensed for cell division

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7
Q

What is a telomere?

A

Caps at ends to prevent deterioration
TTAGGG repeated

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8
Q

What is a centromere?

A

Noncoding DNA that binds to mitotic spindle with satellite DNA sequences

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9
Q

What are the two types of chromatin?

A

Heterochromatin - condensed
Euchromatin - dispersed

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10
Q

What are the two types of heterochromatin?

A

Constitutive - always condensed
Facultative - can be condensed or as euchromatin

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11
Q

When does DNA replication occur?

A

In the S phase of the cell cycle

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12
Q

What are the requirements for DNA replication?

A

Template DNA
Free deoxyribonucleotides
Unwinding by helicase
RNA primer

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13
Q

What initiates replication?

A

RNA primer by DNA primase
-Used multiple times on lagging strand

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14
Q

What are the functions of DNA polymerase?

A

DNA elongation
Proofreading and correction

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15
Q

What removes RNA primers?

A

DNA polymerase I in prokaryotes
RNase H in eukaryotes

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16
Q

How are DNA strands resealed?

A

DNA ligase

17
Q

What is the function of topoisomerases?

A

Unwind supercoiling and any tangles ahead of replication fork

18
Q

What are the DNA polymerases in prokaryotes and its functions?

A

DNA pol I - RNase activity and fills in gap left
DNA pol II - repair
DNA pol III - elongation

19
Q

What are the types and functions of DNA pol in eukaryotes?

A

DNA pol alpha - synthesis of short fragments from primer - Okazaki
DNA pol gamma - mitochondrial DNA replication
DNA pol delta and epsilon - elongation from pol alpha

20
Q

What are the properties topoisomerase type I?

A

Cleaves one strand of DNA
ATP not required

21
Q

What are the properties of topoisomerase type II?

A

Cleaves both strands of DNA
Requires ATP

22
Q

What is the role of telomerase?

A

Adds telomeres using RNA template
Not expressed in most cells

23
Q

What are 5 causes of DNA damage?

A

Replication errors
Spontaneous
Chemical
Reactive oxygen species
Radiation (UV and ionizing)

24
Q

What are three types of DNA damage?

A

Single base
Two base
Strand breaks

25
Q

What are 5 repair pathways?

A

Base excision
Nucleotide excision
Nonhomologous end joining
Homologous recombination
Mismatch repair

26
Q

What is the general mechanism for DNA repair?

A

Recognition
Excision
Replacement
Ligation

27
Q

What are the types of single base damages?

A

Incorrect base pairing
Alteration of bases (chemical changes or deamination)
Deletion of bases
Insertion of extra nucleotides

28
Q

What is base excision repair?

A

2 step removal of damaged base
-base removed
-sugar removed
DNA pol adds new nucleotide
Nick sealed by DNA ligase

29
Q

What are the types of two base alteration?

A

UV light causing thymine-thymine or C-C or C-T
Two base alteration - crosslinking
-interstrand or intrastrand

30
Q

What type of DNA damage occurs with bulky adducts?

A

Cause kinks in DNA structure

31
Q

What is nucleotide excision repair?

A

Remove section of one strand and replace

32
Q

What is non-homologous end joining?

A

Double-stranded staggered break with loss of some nucleotides before ends are rejoined
Error prone

33
Q

What is homologous recombination?

A

Occurs after replication
Double-stranded break with nucleotide loss, but repaired using information for sister chromatid

Foundations 1 (28 decks)

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