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BIOL 322 Genetics > Exam 1 - Chp 4: Descent with Modification - Continuity and Variation in the Genome > Flashcards

Exam 1 - Chp 4: Descent with Modification - Continuity and Variation in the Genome Flashcards

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Biology 101 flashcards
1
Q

How many hydrogen bonds between adenine and thymine?

A

2

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2
Q

How many hydrogen bonds between cytosine and guanine?

A

3

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3
Q

What is semiconservative DNA replication?

A

DNA replication occurs to produce two double stranded DNA molecules consisting of a parent strand paired with a daughter strand

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4
Q

What temperature is DNA heated to to cause it to anneal (separate)?

A

95C

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5
Q

What do origin binding proteins do?

A

Recognize the origin of replication

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6
Q

What does DNA helicase do?

A

Separates DNA strands for replication

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7
Q

What do single strand binds proteins (SSBs) do?

A

Keep DNA strands apart long enough for DNA polymerase to bind during DNA replication

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8
Q

What does primase do in DNA replication?

A

Initiates synthesis of each Okazaki fragment and the leading strand by creating an RNA primer so DNA polymerase can add to the primer because it has a 3’ OH group

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9
Q

Why does DNA polymerase require RNA polymerase to begin DNA synthesis?

A

DNA polymerase can only add nucleotides to the 3’ OH group of another nucleotide which is not available when starting a new DNA strand, RNA polymerase does not require a 3’ OH group to being RNA synthesis

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10
Q

What are Okazaki fragments?

A

Because the replication fork heads towards the 3’ end of the template lagging strand, DNA polymerase must synthesize the lagging strand in fragments as it because it is moving in the 3 → 5 direction of the new lagging strand

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11
Q

Going towards the replication fork, which direction does the template leading strand go? The template lagging strand?

A

3’ → 5’
5’ →3’

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11
Q

How many replication forks form at the origin of replication? where do they go?

A

Two; opposite directions along the DNA strand

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12
Q

How is the fragmented lagging strand completed in DNA replication?

A

Okazaki fragments are sealed together by DNA ligase

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13
Q

How is the RNA primer that initiated DNA synthesis handled without losing genetic information?

A

It is complementary to a repetitive telomere sequence known as TERC so the RNA primer can be degraded and only a TERC sequence is lost

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14
Q

How do eukaryotes prevent loss of genetic information in offspring if telomeres and constantly decreasing in size?

A

Telomerase copies TERC and maintains its length in germlin cells

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15
Q

How does prokaryotic DNA replication end?

A

When the two replication forks reach each other on the other side of the circular DNA molecule

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16
Q

What is a clamp loader and sliding clamp involved in DNA replication?

A

The clamp loader loads the sliding clamp onto DNA which stabilizes DNA polymerase during replication

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17
Q

What does topoisomerase do?

A

cuts double stranded DNA downstream of replication fork to relieve tension from supercoiling

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18
Q

What are the five things needed to perform PCR

A

DNA
DNA polymerase
Primers in high concentration
dNTPS
Buffer and MgCL2

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19
Q

What DNA polymerase is typically used in PCR?

A

Taq polymerase - found in thermos aquaticus that lives in deep sea vents so their proteins can withstand annealed temperature

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20
Q

What are the four steps of PCR?

A

1) Anneal by heating up sample to 95 C
2) primers bind to target sequences
3) DNA polymerase adds dNTPs
4) Two double strands now produced, repeat process over and over

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21
Q

What are tautomers?

A

isomers of nucleotide bases that nucleotides can easily switch to

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22
Q

What are consequences of tautomers?

A

Mismatch pairing, unstable pairing, incorrect base pairing during replication

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23
Q

Describe proofreading that occurs during replication

A

DNA polymerase reverses, uses exonuclease to excise base and polymerase replaces it

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24
Q

During what stage of cell division do cells check their DNA for most mistakes?

A

G2 phase, after S-phase DNA replication

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25
Q

What happens if a cell detects DNA damage during a checkpoint in cell division?

A

Cell division is halted and the damage is fixed

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26
Q

What happens if cell damage cannot be fixed in a eukaryotic cell?

A

Apoptosis

27
Q

What is apoptosis?

A

Programmed cell death

28
Q

What response does a bacteria have to DNA damage?

A

SOS response; de-repress DNA repair genes and inhibit cell division. Repress SOS response once damage is fixed

29
Q

How is mismatch repair preformed?

A

Mismatch and surround bases are removed by exonuclease, replaced by DNA polymerase, and the DNA backbone is sealed by ligase

30
Q

How does the cell identify the original/correct strand in mismatch repair?

A

It is methylated, cell also methylates repair once done

31
Q

How is UV damage repaired?

A

Photolyase recognizes pyrimide dimers caused by UV rays and and breaks it apart using photo reactivation -energy from light

32
Q

How do humans repair UV damage?

A

Excision repair, do not have photoylase

33
Q

How is overmethylation of bases fixed?

A

Direct repair - breaking of bonds

34
Q

How is the breakage of between the sugar and base repaired?

A

Base excision repair via exonuclease, DNA polymerase, and ligase

35
Q

How are changes to multiple adjacent bases or extension damage fixed?

A

Nucleotide excision repair using exonuclease, DNA polymerase, and ligase

36
Q

How are double stranded breaks repaired?

A

Using ligase but can cause major issues if not attached correctly

37
Q

What happens if a mutation affects essential cell function?

A

Apoptosis

38
Q

What process does mutation need to affect to cause the cell to proliferate without normal growth?

A

Cell division

39
Q

If a mutation affects non-essential function, what happens to the cell?

A

Maintains relatively normal function, unharmful

40
Q

What do tumor suppressor genes do?

A

Regulate cell growth and prevent uncontrolled division

41
Q

What do proto-oncogenes do?

A

Promote normal cell growth and division

42
Q

What are oncogenes?

A

Proto-oncogenes that have been mutated causes rapid cell replication

43
Q

What does a mutation in a tumor suppressor gene do?

A

Allow unregulated cell growth and proliferation leading tumors

44
Q

What is p53?

A

A gene crucial for monitoring DNA integrity, can turn genes on and off, and activate repair processes or cell death

45
Q

What is retinoblastoma?

A

A common tumor suppressor gene that stops cells from dividing too rapidly

46
Q

What are the three major ways proto-oncogenes becomes oncogenes?

A

Mutation
Chromosomal Translocation
Regulation of protein product due to increased mRNA stability

47
Q

What is chromosomal translocation?

A

Gene broken down in the middle during crossover event or double stranded break and is reincorporated incorrectly

48
Q

What is a driver mutation?

A

Mutation responsible for transformation from normal growth to unregulated growth

49
Q

What is a passenger mutation?

A

Mutation that arises and accumulates more as the cell divides randomly after the driver mutation

50
Q

Is the passenger or driver mutation the cause of cancer?

A

Driver

51
Q

What are three possible fates of mutations?

A

Advantageous change
Neutral change
Deleterious change

52
Q

What are 4 places with DNA that advantageous or deleterious mutations occur at?

A

1st or 2nd base pair of codon
Protein coding sequences
Control regions
Noncoding RNA that has a task

53
Q

What are 3 places within DNA that neutral changes occur at?

A

Noncoding DNA
3rd base pair in codon
Pseudogene

54
Q

What kind of selection do deleterious changes in DNA result in?

A

purifying selection

55
Q

What is high number of neutral mutants within a population signify?

A

Purifying selection

56
Q

What kind of selection do advantageous changes in DNA result in?

A

Positive selection

57
Q

What can be used to map out genetic changes

A

Phylogenic trees

58
Q

What does monophyletic mean?

A

Branch of phylogenic tree that includes common ancestor and all of its descendants

59
Q

What does polyphyletic mean?

A

Groups on phylogenic tree derived from different common ancestors

60
Q

What does paraphyletic mean?

A

Group descended from a common ancestor but not including all descendants

61
Q

What is descent with modification?

A

Small changes between generations eventually lead to large changes within populations and species

62
Q

What is a transition mutation?

A

When a pyrimide is replaced with another pyrimide or a purine with another purine

63
Q

What is transversion mutation?

A

A pyrimide is paired with another pyrimide or purine with purine

64
Q

Is a transversion or transition more harmful? Which is easier to detect? Why?

A

A transversion mutation is more harmful and easier to detect because it distorts helix structure by changing distance between the two DNA strands

BIOL 322 Genetics (9 decks)

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