Cycle 4 (Workshop + Study Session) Flashcards

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1
Q

Define and state the types of DNA damage

A

Exogenous: Coming from outside the cell (e.x. UV, IR, chemicals)
Endogenous: Coming from inside the cell (e.x. Cell Metabolism (ROS), replication errors)

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2
Q

What is the difference between mutations and DNA Damage?

A

Mutations are changes in the double stranded DNA sequence, while DNA damage is any change to DNA that is not double stranded

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3
Q

True or False:
Genetic variation refers to DNA damage

A

False, genetic variation refers to mutations

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4
Q

Can DNA damage lead to mutations?

A

Yes

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5
Q

What are ROS?

A

Reactive Oxygen Species
Very electronegative and unstable, will take electrons away from any sort of molecule nearby to regain stability (Targets DNA)

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6
Q

What can taking electrons away from DNA lead to?

A

Double-stranded breaks

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7
Q

What is the Oxygen Paradox?

A

While oxygen is crucial to many cell functions, too much of it can ultimately lead to cell death

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8
Q

Too much oxygen causes _________ ______

A

Oxidative Stress

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9
Q

What helps our cells combat the effects of ROS?

A

Antioxidants

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10
Q

True or False:
DNA Polymerase can proofread during replication

A

True

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11
Q

How does DNA polymerase recognize that a mistake has been made?

A

Detection of distortion in the DNA backbone

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12
Q

How does DNA polymerase remove incorrect bases?

A

Moves backwards and removes the incorrect base through 3’-5’ exonuclease

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13
Q

True or False:
3’-5’ exonuclease can remove several bases at a time from the end of the chain

A

False, 3’-5’ exonuclease can remove bases one at a time from the end of the chain

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14
Q

Describe the _ steps in mismatch excision repair

A

4

Repair enzymes detect the distortion

Mismatch/repair enzymes bind to the damaged region and excise (cleave) the backbone through endonuclease activity

DNA polymerase fills in the gap

Ligase seals the nick

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15
Q

Define:
Mismatch repair

A

When the mistake is brought upon by mistakes by DNA polymerase III that are not fixed by proofreading

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16
Q

Define:
Excision repair

A

Used when there are exogenous sources of DNA damage

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17
Q

True or False:
Repair enzymes that have endonuclease activity can make cuts at the ends of the backbone

A

False, repair enzymes that have endonuclease activity can make cuts that are within the backbone

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18
Q

Define:
Thymine Dimers

A

A type of damage that occurs when adjacent thymines are exposed to UV light

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19
Q

How are thymine dimers repaired?

A

Photolyase + white light
Excision repair

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20
Q

Describe a thymine dimer

A

Formed under UV light, when two T bases to covalently bond together (forming a dimer)

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21
Q

Define:
Non-Homologous End Joining (NHEJ)

A

Repairs double-stranded breaks by joining blunt ends without using a template

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22
Q

True or False:
NHEJ is relatively precise

A

False, NHEJ is very sloppy as it grabs floating nucleotides and puts them back in random orders and numbers

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23
Q

What mutations can NHEJ result in?

A

Insertion, deletion, or inversion

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24
Q

True or False:
Only 90% of your DNA is essential coding

A

False, only 10% of your DNA is essential coding

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25
Q

What does 2% in the 10% of essential coding account for?

A

Protein coding

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26
Q

What types of mutations are there?

A

Substitution, deletion, insertion, and inversion

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27
Q

Define:
Substitution mutation

A

Also known as point mutation, when one base changes

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28
Q

Define:
Deletion mutation

A

When a base pair is removed

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29
Q

Define:
Insertion mutation

A

Base pair is added

30
Q

Define:
Inversion mutation

A

When a sequence is flipped

31
Q

What are the _ types of point mutations?

A

3
Silent
Nonsense
Missense

32
Q

Define:
Silent point mutation

A

The base change will result in a change in the mRNA, but still codes for the same amino acid

33
Q

Define:
Nonsense point mutation

A

The base change will result in a change in the mRNA and code for a premature stop codon, potentially leading to a nonfunctioning protein

34
Q

Define:
Missense point mutation

A

Base change will result in a change in the mRNA and will change the amino acid it codes for; may cause an issue

35
Q

Define:
Single Nucleotide Polymorphisms (SNPs)

A

Single nucleotide changes “in pairs”

36
Q

True or False:
SNPs are the most common type of genetic variation between individuals

A

True

37
Q

True or False:
SNPs will cause individuals to develop certain diseases

A

Not exactly. Majority of SNPs have no effect on health and development

38
Q

Backward slippage occurs in the ___________ strand

A

Synthesized strand

39
Q

Backwards slippage will cause _________, causing the copied DNA to be ______

A

Insertion
Longer

40
Q

Where is backward slippage more common?

A

More common in regions where the DNA sequence is repetitive

41
Q

In backwards slippage, a strand slips during replication and creates a ____

A

Loop

42
Q

Why is the loop created in backwards slippage not repaired?

A

It is very stable and not recognized by DNA polymerase III or other repair enzymes

43
Q

What kind of slippage occurs in the template strand?

A

Forward slippage

44
Q

Forwards slippage will cause _________, causing the copied DNA to be ______

A

Deletion
Shorter

45
Q

When does forward slippage happen?

A

Can happen when the DNA polymerase is going too fast

46
Q

True or False:
Tautomeric shifts are NOT spontaneous events

A

False, tautomeric shifts are SPONTANEOUS events

47
Q

True or False:
Tautomeric shifts DO NOT result in a mismatch

A

True

48
Q

If a tautomeric shift is not recognized by the cell as a mismatch, what is it?

A

A shift in preferential base pairing

49
Q

Thymine and Guanine are mainly in ____ form, but can shift to ____ form

A

KETO
ENOL

50
Q

Adenine and Cytosine are mainly in _____ form, but can shift to _____ form

A

AMINO
IMINO

51
Q

What does ENOL T pair with?

A

Guanine

52
Q

What does IMINE A pair with?

A

Cytosine

53
Q

Define:
Mutagens

A

Things that increases the rate of mutations in cells

54
Q

True or False:
DNA polymerase has perfect specificity

A

False, DNA polymerase does not have perfect specificity

55
Q

What is an example of analogous molecule to thymine?

A

5-bromouracil

56
Q

What can analogous molecules do to DNA replication?

A

Analogs are much more unstable in most cases and thus more likely to undergo tautomerization and cause mutation through tautomeric shifts

57
Q

Define:
Analogous

A

Similar in structure

58
Q

Define:
Transition Mutation

A

Purine to purine OR Pyrimidine to pyrimidine

59
Q

Define:
Transversion Mutation

A

Purine to pyrimidine OR Pyrimidine to purine

60
Q

Give an example of a transition mutation:

A

AT to GC

61
Q

Give an example of a transversion mutation

A

AT to CG

62
Q

What are transposable elements?

A

Short regions of DNA that are able to move (“jump”) around the genome

63
Q

Where can we generally find transposable elements?

A

TEs are generally found in between genes - in the “safe havens”

64
Q

True or False:
Transposable Elements generally appear in between genes, which affects gene function

A

False, TEs generally appear in between genes in the “safe havens” so they don’t interfere with the function of genes

65
Q

Genome size does not necessarily reflect the ______ of _____ an organism has

A

Number
Genes

66
Q

How many TEs can a genome have?

A

Many, depending on the organism.

67
Q

___ are the reason that genomes can be so _____

A

TEs
Large

68
Q

True or False:
Most transposable elements are dead

A

True, most are silenced/deactivated by the host and longer undergo transposition (jumping around)

69
Q

Can transposable elements still be active?

A

Yes, few can be active and fewer still can transpose

70
Q

If a TE lands on a gene, what can it cause?

A

Can cause disease-causing mutations OR gene shuffling

71
Q

Define and give an example of a:
Multifactorial Disease

A

A disease that can be caused by a variety of factors, both environmental (exercise, diet, lifestyle) and genetics (SNPs)

E.x. Heart disease

72
Q

True or False:
TEs can take a piece of genome and add it to another section

A

True, it can do this under a different promoter