Nucleic Acids Flashcards

1
Q

Fred Griffith

A

discovered transformation

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2
Q

pneumococci R strain

A

no capsule, not pathogenic

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3
Q

pneumococci S strain

A

pathogenic, encapsulated

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4
Q

transformation of pneumococci

A

combined harmless R bacteria with heat-killed S bacteria –> R turned to S and caused pneumonia

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5
Q

Avery, McCarty, MacLeod

A

identified that DNA was the transforming principle

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6
Q

Hershey and Chase

A

used bacteriophages to determine if genetic information was DNA or protein

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7
Q

Hershey and Chase experiment

A

labeled one batch of phage with S (in protein) and one with P (in DNA) –> bacteria infected with phage –> centrifugation –> P was found in bacteria but S was found in supernatant

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8
Q

DNA base pairing

A

A with T and C with G

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9
Q

Watson-Crick model of DNA

A

bases are on inside, phosphate backbone on outside; 3.4A between bases, 10.6A per turn

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10
Q

Meselson-Stahl

A

found out that DNA was semi-conservative

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11
Q

Meselson-Stahl experiment

A

grew E. coli for several generation with N15 as only nitrogen source –> shift to N14 –> isolate DNA at various times –> weigh by centrifugation

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12
Q

What are genes?

A

a discrete region of DNA that encodes functional RNA with coding and regulatory regions

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13
Q

central dogma violations

A

RNA viruses (RNA –> RNA), retroviruses (RNA –> DNA), non-protein genes (RNA –> function), epigenetics

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14
Q

roles of DNA

A

storage of genetic information and structure

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15
Q

roles of RNA

A

storage of genetic information, structure, transfer of information, information interpretation, enzymes, gene regulation

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16
Q

Watson-Crick model

A

helical molecule will give an X-ray diffraction pattern that forms an X –> Rosalind Franklin’s X-ray diffraction of DNA showed an X

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17
Q

Meselson-Stahl results

A

DNA has heavy banding at beginning –> first generation has halfway between heavy and light –> after two generation some are intermediate and some are light

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18
Q

DNA backbone

A

ribose sugar + phosphate

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19
Q
A

ribose, -OH at 2’

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20
Q
A

2-deoxyribose; no -OH at C2

21
Q

linkage between ribose sugar and phosphate

A

phosphodiester linkage

22
Q

purines

A

two rings, A and G

23
Q

pyrimidines

A

1 ring; T and C and U

24
Q
A

adenine

25
Q
A

guanine

26
Q
A

cytosine

27
Q
A

thymine

28
Q
A

uracil

29
Q

nucleoside

A

DNA base + ribose sugar

30
Q

nucleotide

A

DNA base + ribose sugar + phosphate group

31
Q

DNA bases are _

A

planar and hydrophobic; hydrogen bonded to each other

32
Q

A and T have _

A

2 hydrogen bonds

33
Q

G and C have _

A

3 hydrogen bonds, higher melting point

34
Q

usual DNA form

A

B form

35
Q

electron microscopy

A

visualize DNA strand if coat it with a metal

36
Q

spectroscopy of ssDNA vs dsDNA

A

dsDNA will have lower peak absorbance

37
Q

ssDNA wavelength at peak absorbance

A

around 260nm

38
Q

melting temperature of DNA

A

point where half DNA is melted; usually around 50-70 degrees celsius

39
Q

What affects stability of double helix?

A

base stacking, H-bonding, salt interactions with phosphates to mask negative charge

40
Q

restriction enzymes

A

cut palindromic sequences (read same forward and backward); used to make recombinant DNA

41
Q

How does DNA keep from getting tangled?

A

supercoiling, topoisomerases, DNA binding proteins

42
Q

topoisomerases

A

help control strain of supercoiling by changing conformation of DNA-linking number

43
Q

topoisomerase I

A

one phosphodiester bond is broken, changing linking number by 1

44
Q

gyrase (type II topo)

A

double strand break; linking number changes by -2

45
Q

novobiocin

A

blocks binding of ATP to gyrase

46
Q

nalidixic acid, ciprofloxacin

A

interfere with breakage and rejoining of DNA by gyrase and are used to treat UTIs

47
Q

bleomycin

A

cervix and uterus, head and neck, testicle and penis, lymphoma

48
Q

etoposide

A

testicle and lung cancers

49
Q

chromatin

A

DNA + proteins