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Molec of Gene > Exam 1 > Flashcards

Exam 1 Flashcards

(54 cards)

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1
Q

A DNA

A

right handed
wider and shorter than DNA B
Form of dsRNA

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2
Q

B DNA

A

right handed
rise = 34 nm
10 bp / turn
better for sequence specific binding

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3
Q

Z DNA

A

left handed
thinner and longer
longest rise

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4
Q

dsRNA

A

A form

b/c of ribose

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5
Q

why does sequence specific binding usually occur through major groove

A

because

  1. greater area
  2. more contacts
  3. easier to distinguish between 4 base pair combinations
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6
Q

alternative tautomeric states of A and C

A

Amino OR Imino

with AMINO more prominent

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7
Q

alternative tautomeric states of T and G

A

Keto OE Enol

with KETO more prominent

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8
Q

Covalent backbone bonds allow DNA bases to do what? Why is this important?

A

Flip out - usefull for:

  1. repair
  2. methylation
  3. recombination
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9
Q

Causes of Z DNA

A
  1. switch between syn and anti conformation

2. sequence containing alternating purines and pyrinadines

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10
Q

Denaturing and reannealing

A

can be denatured by heat, high pH and reannealed by slow cooling

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11
Q

Melting Temp (Tm) variables

A
  1. sequence
  2. length
  3. salt conc
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12
Q

higher salt effect on melting temp

A

higher salt content = higher melting temp

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13
Q

levels of DNA structure

A
  1. primary
  2. secondary
  3. tertiary
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14
Q

primary DNA structure

A

nucleotide sequence

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15
Q

secondary DNA structure

A

double helix structure

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16
Q

tertiary DNA structure

A

folding of helix to fit into the cell

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17
Q

DNAs that are covalently closed circles

A

some bacterial chromosome
plasmids
some virus

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18
Q

cccDNA

A

covalently closed circle DNA

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19
Q

cccDNA charcteristic

A

“topologically constrained” therefore fixed number of times that it can coil

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20
Q

twist

A

=# of times one strand wraps around the other

one twist = 10 bp

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21
Q

writhe

A

=# of times double helix crosses over itself

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22
Q

Linking number

23
Q

Relaxed cccDNA

Study These Flashcards
A

Lk = Lk0 = bp/10.5

24
Q

supercoiling occurs when

Study These Flashcards
A

Lk does not equal Lk0

25
Topoisomerases
cleave phosphodiester bond so helix can swing around as it unwinds
26
Topo I
breaks and reforms at one strand no ATP changes Lk by one
27
Topo II
ds breaks needs ATP changes Lk in steps of 2
28
What is DNA gyrase a type of
Topo II
29
DNase I
nicks DNA, releases supercoiling
30
topos use what to hold the DNA after cut?
a covalent intermediate | connects 3 OH to tyrosine
31
Which enzyme can increase supercoiling?
DNA gyrase
32
how can super coiled DNAs (topoisomers) be separated from one another?
by gel electrophoresis most supercoiled will move the fastest linear DNA is medium speed circular DNA is slowest
33
why U not T in RNA?
has greater range of base pairing enhanced self complimentary abilities can also do unconventional bps like base to backbone or base triples
34
ribose in RNA
results in A form structure less capable of sequence specific recognition by protein (b/c smaller major groove) more reactive
35
5 functions of RNA
1. carry information (mRNA) 2. adapter (tRNA) 3. structure (ribosome) 4. regulation (of translation) 5. catalytic (ribosome, RNA splicing)
36
Is RNA genomic?
only in some viruses
37
secondary structure of protein
= local confomation | 3D arrangement of short strands of AAs
38
tertiary structure of protein
= folded arrangement of entire peptide chain under physiological conditions
39
protein domains
a part of a polypeptide chain with a folded structure that does not depend on any other part of the protein for stabilization usually between 50 and 300 AAs long
40
Motif (sequence)
short AA sequence with characteristic properties
41
Motif (structural)
domain structure that occurs in many different proteins | ex. helix turn helix
42
classes of protein domains
FOLD and HOMOLOGY
43
FOLD (protein domain class)
2 structure + chain passage from one helix/strand to another
44
HOMOLOGY
homologous proteins | proteins similar enough to suggest a common evolutionary origin
45
Proteins that recognize DNA sequences
homeodomains zinc fingers luecine zipper
46
zinc finger
most abundant DNA recognition domain zinc ion holds together folded domain when binds to DNA short alpha helix enters major groove, and zinc finders connect successive bps
47
leucine zipper
2 alpha helicies form a pincer on DNA
48
homeodomain
helix turn helix DNA binding domains
49
How many DIFFERENT chromosomes are found within the nucleus of Homo Sapiens?
24
50
How many different chromosomes are found in Drosophila? | In Drosophila nuclei?
5 4
51
copy number
how many copies of each chromosome something has
52
size of human genome
3.2 B bp
53
number of genes in humans
20,000
54
distance between euk origin of rep
every 30-40 kb

Molec of Gene (2 decks)

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