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funmed > 18 > Flashcards

18 Flashcards

1
Q

what are the purines

A

pure As Gold

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2
Q

what are the pyrimidines

A

CT

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3
Q

whats a nucleotide

A

phosphate group, sugar, and base

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4
Q

to what end are new nucleotides added

A

3´

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5
Q

how many bonds between G and C

A

3

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6
Q

how many bonds between A and T

A

2

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7
Q

what type of bon delinks the base pairs

A

covalent

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8
Q

what kind of bond is in the sugar phosphate backbone

A

peptide bonds

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9
Q

what free structure is on the 5´end

A

free phosphate group

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10
Q

what free structure is on the 3´end

A

unliked OH group on sugar backbone

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11
Q

how many histones does DNA wrap around

A

8

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12
Q

What is the name of the 8 core histones (and linker histone)

A

2 H2A 2 H2B 2 H3 and 2 H4 and linker histone H1

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13
Q

at what part of the histones do the modifications occur

A

tail

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14
Q

what is the main function of histone mofidicaiton

A

they regulate how tightly histones are bound to DNA and therefore whether the chromatin is in the form of a euchromatin or a heterochromatin

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15
Q

What two molecules control the loops that histones create with DNA

A

Cohensins and CTCF

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16
Q

how much more compact are chromosomes in metaphase compared to DNA itself

A

10,000x

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17
Q

at what stage of the cell cycle is the chromosome the densest

A

during mitosis

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18
Q

if the CC lasted a day, how long would interphase last

A

22-24 hrs

19
Q

if the CC lasted a day, how long would mitosis last

A

30-60mn

20
Q

Where does DNA replication start

A

at the origin of replication

21
Q

what form of chormatin is open

A

euchromatin

22
Q

what form of chormatin is closed

A

heterochromatin

23
Q

how long does the replication of the whole genome take

A

8-10 hrs

24
Q

to which end are nucleotides added

A

3’

25
Q

on what strand are Okazaki fragments added

A

lagging strand

26
Q

in what phase of the CC does DNA replication occur

A

S phase

27
Q

what is the function of topoisomerase and how does it work

A

Prevents supercoiling by making nicks in DNA to allow it to relax and DNA ligase sticks it back

28
Q

What are two types of antibiotics that target DNA replication

A

Fluoroquinolones and Trimethoprim - Sulfamethoxazole

29
Q

what bacteria is Fluoroquinolones used for? what enzyme does it target

A

targets topoisomerase in bacteria

Aerobic Gram-positive
Aerobic Gram-negative Some anaerobic Gram-negative species and M.tuberculosis

30
Q

list names of Fluoroquinolones

A

Nalidixic acid ciproflaxacin
levofloxacin
gemifloxacin

31
Q

in what ratio is Trimethoprim - Sulfamethoxazole found

A

1:5
T:S

32
Q

what bacteria is Fluoroquinolones used for? what step does it target

A

Aerobic Gram-positive and Gram-negative species

Target nucleotide synthesis

33
Q

on average when a cell divides. how many mistakes are made

A

12-20

34
Q

What are the two major types of defects in DNA

A

single strand defect

double strand defect

35
Q

what is base excision repair

A

If you have deaminated cytosine it becomes uracil. Uracil DNA glycosylase removes the U then sugar phosphate is removed
And DNA pol adds new nucleotides and DNA ligase seals the nicks

36
Q

what is nucleotide excision repair

A

If you have ionizing radiaiton, you can get pyrimidine dimers being fomed not at the sugar phspohate sude base bs other base. Pyrimidine dimer elision. Super dangerous because RNA cant be made correctly.
Basically nuclease breaks DNA at 12 nucletoide stretch in bacteria and 20 nucleotdeis in humansm then helicase removes that nucletodie strech and the DNA pol and DNA ligase replaces that strand with a normal copy

37
Q

what is mismatch repair

A

Two main enzymes
• MutS binds to mismatched base pair
• MutL scans nearby DNA for nick and triggers strand removal to the
Mismatch
Muts and mut l bind to msitake mutl scans dna looking for a gap, causing remocal of the strand from the gap to the error and replaces it with a new strand.

38
Q

what is non homologous end joining

A

accidental ds break
loss of nucleotides due to degradation from ends
it is linked together despite missing bases
Even though its not the same, its reparied and its function structurally perfectly well.

39
Q

what is non homologous end joining

A

accidental ds break
loss of nucleotides due to degradation from ends
Finds sister chromosome and copies it into the gap

40
Q

what gene is mutation within the NER that causes problems

A

Xeroderma pigmentosum (XP) mutation in a polymerase

causing

Skin cancer, cellular UV sensitivity, neurological abnormalities

41
Q

what gene is mutation within the mismatch repair that causes problems

A

Mutation in MutS, MutL

causes colon cancer

42
Q

what gene is mutation within the mismatch repair that causes problems

A

Mutation in MutS, MutL

causes colon cancer

43
Q

what gene is mutation within the homologous recombination repair that causes problems

A

BRCA2 mutation causes breast and ovarian cancer

funmed (18 decks)

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