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MCAT bio > molecular genetics > Flashcards

molecular genetics Flashcards

(105 cards)

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1
Q

central dogma

A

DNA –> RNA –> protein
- transcription and translation

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2
Q

hershey-chase experiment

A

radiolabeled sulfur and phosphorus to distinguish where genetic info was (protein vs nucleic acids)
- result was radiolabeled phoshporus which is in dna not protein

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3
Q

reverse transcriptase

A

allows dna to be transcribed from rna
- retroviruses
- special kind of dna polymerase that operates with rna template

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4
Q

codon

A

3 dna nucleotides that code for an amino acid
4^3 = 64 combinations

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5
Q

degeneracy

A

multiple codons can make the same amino acid
- increase resistance to error

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6
Q

wobble position

A

provide protection against mutation in the final nucleotide of a codon. most codons are defined by the first two nucleotides

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7
Q

stop codons

A

UGA, UAG, UAA

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8
Q

start codon

A

AUG (met)

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9
Q

watson and crick model of dna

A

dna is a double helix of antiparallel strands with a sugar phsophate backbone
- complimentary basepairing
- interior stabilized by h bonds between bases and hydrophobic interactions between stacked bases

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10
Q

base stacking

A

arrangement of nucleotide nitrogenous bases that allow for hydrophobic interactions`

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11
Q

compliementary dna strands

A

are complimentary and antiparallel (be aware of directionality when looking at question wording)

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12
Q

how is dna organized in eukaryotes

A

linear chromosomes in the nucleus

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13
Q

autosomes

A

22 chromosomes in humans that are somatic cells and have two copies each. 1 maternal and 1 paternal

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14
Q

sex chromosomes

A

two each
female XX
male XY

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15
Q

how is the massive content of dna squeezed into chromosomes

A

histones and chromatin

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16
Q

histones

A

proteins that are wound around dna with subproteins: h1 h2A h2B H3 H4
core: two dimers ofh2a and h2b and a tetramer of h4 and h3
h1: linking unit

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17
Q

nucleosomes

A

dna-histone complex
- beads on a string

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18
Q

chromatin

A

structure formed by nucleosomes (dna and histones)

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19
Q

euchromatin

A

loose configuration that allows dna to be easily transcribed
- during interphase (allows for transcription)

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20
Q

heterochromatin

A

tighly coiled dense form of chromatin that is visible during CELL DIVISION

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21
Q

how do histones and dna interact

A

charge driven interactions
- histones are positive and dna is negative

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22
Q

acetylation of histones

A

reduce their positive charge, and loosen binding on dna allowing for an increase in dna transcription

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23
Q

semiconservative replication

A

dna replication where end product is 1 original strand and one new strand

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24
Q

meselson-stahl experiment

A

experiment that distinguished between old and new dna
they grew radioactive N in e. coli and traced it
- found that dna is semi-conservative

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25
orgin of replication
start of dna replication - one place in prok - multiple in euk
26
helicase
unwinds dna for transcription - seperates the strands
27
single stranded binding proteins
keep the strands seperated
28
primase
short rna primer with a free 3' oh that is used to start dna synthesis
29
dna polymerase
reads dna from 3-5 and synthesizes from 5-3
30
dna gyrase/ topoisomerase
alliviates supercoiling created by helicase
31
ligase
links okazaki fragments on the lagging strand
32
DNA polymerase direction
can only add in the 5' to 3' direction and read in the 3' to 5'
33
lagging strand
made into short sequences by dna polymerase that must be ligated together by ligase
34
dna polymerase 1
prokaryotic dna polymerase that assists with okazaki fragments - removes rna primer through excision repair
35
dna polymerase 2
primary eukaryotic dna polymerase involved with repair
36
dna polymerase 3
primary eukaryotic polymerase for dna replication
37
dna polymerase alpha
initiates synthesis in replication in both strands
38
dna polymerase delta
takes over from dna polymerase alpha amd adds dna after the rna primer is removed
39
dna polymerase epsilon
extension of leading strand and dna repair
40
dna polymerase beta
dna repair
41
dna polymerase gamma
replicates miDNA
42
telomerase
extends telomeres at the end of eukaryotic chromosomes
43
what are telomeres
repeating sequences at the end of the chromosome that cope with the fact that dna polymerase can't replicate the end of a chromosome
44
what kind of cells is telomerase active in
stem and cancer (not somatic)
45
transcription
transcribe dna to rna in the nucleus. results in mrna
46
rna polymerase
enzyme that synthesizes pre-mrna during transcription - synthesizes in the 5' to 3' direction
47
promotor region
where rna polymerase binds to dna to begin transcription with the assitance of transcription factors
48
TATA box
most important promotor in eukaryotes
49
template strand for rna synthesis
antisense strand
50
sense strand
the non - template strand that corresponds to the codons on the mRNA molecule
51
requirements for dna polymerase
1. always need a template 2. they add in the 5-3 ' direction 3. they cannot start from scratch (need primer)
52
rna polymerase 2
default rna polymerase that synthesizes hn RNA (precursor to mRNA)
53
hnRNA (heterogeneous nuclear)
precursor to mRNA that must undergo post-transcriptional modification 1. poly a tail 2. 5' cap 3. splicing
54
RNA polymerase 1
synthesizes ribosomal rna in nucleolous
55
rna polymerase 3
synthesizes trna and rRNA
56
does post transcriptional modification of rna occur in prokaryotes?
no, only eukaryotic rna experiences poly A tail addition, 5' cap, and spliciing
57
why does prokaryotic rna not undergo post transcriptional modification?
transcription and translation occur simultaneously so there is no time for modification
58
3' poly A tail
string of 250 adenine nucleotides to the 3' end of the hnRNA - protects mrna from rapid degredation in the cytosol - speed of mrna degredation depends on length of the poly A tail
59
5' cap
7-methylguanylate triphosphate cap on the 5' end of the hnRNA - prevents premature degredation and prepares the RNA complex for export from the nucleus
60
splicing
noncoding (introns) are removed and exons (coding sequences) are left in the RNA and ligated together - exons exit the nucleus - exons can be alternatively spliced leading to protein variation -carried out by the spliceosome and protein complexes --> snRNPs
61
alternative splicing
various combinations of exons produced by the splicosome that allows for large variation in protein produces
62
small nuclear ribonuclear proteins (snRNPs)
spliceosome + small nuclear RNAs and protein complexes
63
translation
process where mRNA is translated into a protein via ribosomes
64
where does translation take place
cytosol in both eukaryotes and prokaryotes
65
tRNA
small RNA molecule with a hairpin structure that translates between codons and amino acids - contains anticodon
66
anticodon
complementary sequence to the mRNA codon
67
aminoacyl tRNA synthetases
charge tRNA with its amino acid by attatching the c terminus of the amino acid to the 3' end of the tRNA molecule - requires 2 atp to charge a tRNA and power the formation of the peptide bond
68
is protein synthesis endergonic or exergonic
endergonic - energy consuming
69
large subunit of euk ribosome and prok
60s and 50s
70
small subunit of euk ribosome and prok
40s and 30s
71
overall ribosome for euk and prok
70 and 80s
72
function of small ribosomal unit
read the RNA
73
initiation
initiator trna binds to the start codon aug and the ribosome is assembled
74
initial amino acid in eukaryotes
methionine
75
initial amino acid in prokaryotes
N-formylmethionine
76
elongation
ribosome reads mRNA from 5' to 3' and synthesizes the polypeptide from N to C terminus
77
a site
contains the next aminoacyl-tRNA complex
78
p site
peptide bond is formed between growing peptide and incoming amino acid
79
e site
trna is no longer charged and detaches from the mrna
80
termination
stop codon (UGA, UAA, UAG) causes release factors to trigger ribosome disassembly and releases the peptide
81
post translational modifications
1. phosphorylation 2. glycosylation 3. protein folding 4. formation of quartenary structure
82
kinases
add phosphates
83
phosphotases
remove phosphates
84
chaperone proteins
assist in protein folding
85
cleavage
cleaving prehormones before they can become active
86
point mutation
one nucleotide base is wrong
87
silent mutation
missense mutation where the amino acid does not change
88
conservative mutation
a type of missense mutation where there is a new amino acid with similar properties
89
non-conservative mutation
missense mutation where amino acid change is large
90
nonsense mutation
premature stop codon
91
frameshift mutation
add/delete amino acid and codons downstream are altered
92
chromosomal deletion
missing a large part of a chromosome
93
chromosomal duplication
adding extra to chromosome
94
inversion
segment is reversed , usually harmless
95
translocation
genes switch places
96
insertion
move between chronosomes
97
transopons
non-coding genetic info that can move between chromosomes
98
anueploidy
too few or too many sets of chromosomes resulting from nondisjunction during cell division
99
monosomy
1 copy of chromosome
100
trisomy
3 copies of a chromosome
101
DNA excision repair
3’ to 5’ endonculease activity
102
Mutagens
Agents that damage dna, usually carcinogens
103
Base excision repair
Small scale errors like mismatched pairs
104
Nucleotide excision repair
Larger lesions of dna, thymine dimers
105
Which interphase checkpoint protects against anueploidy
M phase checkpoint

MCAT bio (12 decks)

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