Module 5—The Molecular Basis of Inheritance Flashcards

(55 cards)

1
Q

Friedrich Miescher

A

accidentally isolated DNA for the first time

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2
Q

Albrecht Kossel

A

discovered 4 nitrogenous bases

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3
Q

Phoebus Levene

A

tetranucleotide hypothesis - incorrect belief that the pattern of bases repeated, making DNA unlikely to be the genetic information

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4
Q

Griffith experiment

A

first demonstration of heredity by something abiotic (DNA from dead cells)

combination of dead pathogenic cells with live harmless cells yielded pathogenic cells (“transformation”)

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5
Q

Avery, Macleod & McCarty

A

showed DNA to be the molecule assimilated into a “transformed” cell

destroying DNA prevented transference, but destroying RNA & protein did not

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6
Q

Hershey & Chase

A

showed that DNA is the genetic material

radiolabelled DNA and protein of phage T2; labels showed DNA in E. coli, but not protein

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7
Q

radiolabelling of phage protein

A

radioactive sulfur

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8
Q

radiolabelling of phage DNA

A

radioactive phosphorus

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9
Q

deoxyribose vs ribose

A

ribose has OH groups at 2’ and 3’

deoxyribose has H at 2’ position instead of OH

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10
Q

purines

structure

A

2 rings

adenine & guanine

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11
Q

pyrimidines

structure

A

1 ring

cytosine, thymine, uracil

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12
Q

Chargaff

A

found that base composition of DNA varies between species, but all species have equal ratios of A to T, and C to G

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13
Q

Franklin & Wilkins

A

produced x-ray crystallography images of DNA helical pattern

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14
Q

Watson & Crick

A

deduced structure of DNA:

  • double helix structure
  • double strand
  • complementary base pairing (only A + T and C + G provided uniform width)
  • antiparallel backbones
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15
Q

3 forms of DNA

A

A form

B form

Z form

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16
Q

most important/normal form of DNA

A

B form

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17
Q

2 areas of DNA where base pairs are accessible

A

major & minor grooves

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18
Q

diameter of DNA

A

2 nm

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19
Q

each base is ___ nm apart

A

3.4

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20
Q

DNA makes a complete turn every ___ bases, or every ____ nm

A

10

34

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21
Q

dehydration of DNA produces…

A

A form

no grooves; tighly wound

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22
Q

tension on DNA produces…

A

Z form

left handed

transient

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23
Q

2 DNA strands are linked by…

A

hydrogen bonds between base pairs

24
Q

bonds between stacked base bairs

A

van der waals

25
\_\_\_ H bonds between A & T
2
26
\_\_\_ H bonds between C & G
3
27
correct model of duplication
semiconservative daughter molecule composed of a new one and an old one
28
Meselson & Stahl
tested semiconservative model of duplication & found it to be correct
29
location of DNA duplication
the replication bubble
30
at the center of the replication bubble
origin of replication
31
where two ends of the replication bubble meet
replication fork
32
helicase
unwinds parental double helix at replication forks
33
single strand binding proteins
bind to strand of parental DNA just inside bubble keep hydrogen bonds from reforming
34
topoisomerase
relieves overwinding strain ahead of replication forks (outside of bubble) breaks, swivels and rejoins strands
35
primase
lays down RNA primers at 5' ends of leading strand and Okazaki fragments
36
DNA pol III
synthesizes new DNA strands by adding new nucleotides to the primers
37
DNA pol I
removes primers & replaces them with DNA nucleotides
38
DNA ligase
joins Okazaki fragments joins 3' end of former primer location to the rest of the leading strand
39
DNA polymerization direction
5' → 3'
40
new nucleotides added to…
OH group at 3' location on deoxyribose
41
free nucleotide structure bond name what is released after binding to new strand? purpose?
_DATP_ has 3 phosphates binds to DNA strand by _phosphodiester_ linkage _pyrophosphate_ (two PO4) released, providing energy to “pay” for synthesis of large polymer
42
complex of all DNA duplication enzymes
DNA replication machine
43
trombone model
DNA replication complex is anchored/stationary in the nucleus DNA is passed through it and duplicated 1 helix enters, 2 helices exit
44
mismatch repair occurs during..
duplication
45
steps of mismatch repair
enzymes detect mismatched base pairs nuclease excises damaged segment DNA pol fills in missing nucleotides correctly ligase seals the free end (3')
46
repair enzymes discovered in humans
107
47
problem for eukaryotes that prokaryotes do not have solution
duplication leads to degeneration of the ends of chromosomes - loss of genes _telomerases_ lay down _telomeres_ (RNA templates) telomeres postpone erosion of chromasomes by providing a buffer region that can safely be lost
48
first level of DNA packing
histones
49
help control nucleosome position/packing
H1 histones histone tails
50
organize chromatin into dense loops during division
condensins
51
condenses are activated by…
mitotic cyclin-cdk complexes
52
period of greatest chromosome density
metaphase
53
densely packed chromatin
heterochromatin
54
loosely packed chromatin
euchromatin
55
suggests order in the organization of the genome during interphase
fluorescent labelling