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First Aid Biochemistry > Molecular > Flashcards

Molecular Flashcards

(87 cards)

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1
Q

“beads on a string” Condensed DNA

A

Chromatin, H1 is the only histone that is not in the nucleosome core

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2
Q

Condensed, transcriptionally inactive, sterically inaccessible

A

heterochromatin

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3
Q

Transcriptionally active chromatin

A

euchromatin

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4
Q

DNA methylation

A

at CpG islands will repress transcription

allows mismatch repair enzymes to distinguish between old and new

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5
Q

Histone methylation

A

reverisbly represses DNA transcription

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6
Q

Histone acetylation

A

relaxes DNA coiling, allows DNA transcription

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7
Q

Uracil

A

Deaminated cytosine, found in RNA

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8
Q

C-G bond

A

3 H bonds, increase in these will increase in melting temp

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9
Q

A-T bonds

A

2 H bonds

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10
Q

Amino acids necessary for purine synthesis

A

Glycine, Aspartate, Glutamine
remember purines are A and G
pyrimidines are C, T, U

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11
Q

De novo Pyrimidines

A

make temporary base (orotic acid)
add sugar + PRPP
modify base

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12
Q

Leflunomide

A

inhibits dihydroorotate dehydrogenase

interferes with nucleotidee synthesis

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13
Q

Mycophenolate & Ribavirin

A

inhibit IMP dehydrogenase

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14
Q

Hydroxyurea in ribonucleotide synthesis

A

inhibits ribonucleotide reductase

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15
Q

inhibits dihydrofolate reductase in humans

A

methotrexate

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16
Q

inhibits dihydrofolate reductase in bacteria

A

trimethoprim

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17
Q

inhibits dihydrofolate reductase in protozoa

A

pyrimethamine

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18
Q

Lesch-Nyhan Syndrome

A

absent HGPRT, X-linked
hyperuricemia, Gout, agression, self-mutilation, retarded, dystonia
excess uric acid production and de novo purine synthesis

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19
Q

HGPRT

A

necesary for purine salvage

converts hypoxanthine to IMP and guanine to GMP

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20
Q

Adenosine Deaminase Deficiency

A

excess ATP and dATP

prevents DNA synthesis and thus decrease lymphocyte count

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21
Q

Unambiguous

A

each codon specifies only 1 amino acid

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22
Q

Degenerate/Redundant

A

most amino acids are coded by multiple codons

exceptions: methionine(AUG) and tryptophan (UGG)

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23
Q

Commaless, nonoverlapping

A

read from fixed starting point as a continuous sequence of bases

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24
Q

Universal

A

genetic code is conserved throughout evolution except in humans (mitochondria)

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25
Helicase
unwinds DNA template at replication fork
26
single-stranded binding proteins
prevent strands from annealing
27
DNA topoisomerases
create a single- or double-stranded break in the helix to add or remove supercoils
28
fluoroquinolones
inhibits DNA gyrase (prokaryoktic topoisomerase II)
29
Primase
makes an RNA primer on which DNA polymerase III can initiate replication
30
DNA polymerase III
5' => 3' synthesis and proofreads 3' => 5' exonuclease prokaryotes ONLY elongates both leading and lagging strands
31
DNA polymerase I
Prokaryotic ONLY | degrades RNA primer and replaces it with DNA
32
DNA ligase
joins Okazaki fragments
33
Telomerase
An RNA-dependent DNA polymerase that adds DNA to 3' ends of chromosomes to avoid loss of genetic material with every duplication
34
Transition mutation in DNA
purine to purine or pyrimidine to pyrimidine
35
Transversion mutation in DNA
purine to pyrimidine or vice versa
36
Silent Mutation
nucleotide substitution by codes for same amino acid
37
Missense Mutation
nucleotide substitution resulting in a changed amino acid like sickle cell disease
38
Conservative missense mutation
new amino acids is similar to the replaced one in chemical structure
39
Nonsense mutation
nucleotide substitution resulting in an early stop codon
40
Frameshift Mutation
deletion of insertion or # of nucleotides not divisible by 3, results in a truncated non-fx protein Ex. Duchenne muscular dystrophy
41
Defective in xeroderma pigmentosum
nucleotide excision repair
42
nucleotide excision repair
endonucleases to remove damaged bases DNA polymerase and ligase to fill and reseal gap repairs pyrimidine dimers from UV light
43
Base Excision Repair
base-specific glycosylase to recognize altered base 1+ nucleotides are moved with AP-endonuclease cleaving 5' end lyase cleaves 3' end DNA-polymerase-beta fills gap and DNA ligase seals it
44
Repair of spontaneous/toxic deamination
base excision repair
45
Defective in hereditary nonpolyposis colorectal cancer
mismatch repair
46
Mismatch repair
newly syn strand is recognized, mismatched nucleotides are removed, gap is filled and resealed
47
DNA repair that is mutated in ataxia telangiectasia
Nonhomologous end joining
48
repairs double-stranded breaks in DNA
Nonhomologous end joining
49
Direction that mRNA and DNA are syn in
5' to 3'
50
mRNA is read in what direction?
5' to 3'
51
Start codon for Prokaryote
AUG, formylmethionine (f-met)
52
Start codon for Eukaryote
AUG, for methionine | may be removed before translation is complete
53
Stop codons
UGA, UAA, UAG
54
Promoter
RNA polymerase finds to DNA upstream from gene locus (TATA box)
55
Enhancer
DNA that alters gene expression by binding transcription factors
56
Silencer
site where repressors bind
57
RNA Polymerase I
in eukaryotes, makes rRNA (most numerous)
58
RNA Polyermase II
in eukaryotes, makes mRNA, largest RNA | opens DNA at promoter site
59
RNA Polymerase III
in eukaryotes, makes tRNA, smallest RNA
60
alpha-amanitin
in Amanita phalloides, inhibits RNA polymerase II
61
Prokaryotic RNA Polymerase
multisubunit complex, makes all 3 kinds of RNA
62
initial RNA transcript
heterogenous nuclear RNA, hnRNA
63
Processes in nucleus following transcription
Capping of 5' end Polyadenylation of 3' end Splicing of introns thusly makes mRNA
64
where mRNA is translated
cytosol
65
AAUAAA
polyadenylation signal
66
snRNPs
bind pre-mRNA at intron to aid in splicing
67
Lariat
looped intermediated for splicing out introns from mRNA | when released, the 2 exons are joined
68
antibodies to spliceosomal snRNPs
anti-Smith antibodies, highly specific for SLE
69
Anti-U1 RNP antibodies
highly associated with mixed CT disease
70
coding segment for protein
exons
71
non-coding segments of DNA
introns
72
tRNA 3' end
CCA - for can carry aminos
73
T-arm of tRNA
contains thymine, pseudouridine, cytosine, necessary for tRNA-ribosome binding
74
D-arm of tRNA
contains dihydrouracil necessary for tRNA recognition to correct aminoacyl-tRNA synthetase
75
mischarged tRNA
reads usual codon but inserts wrong amino acid
76
aminoacyl-tRNA synthetase
scrutinizes AA before and after it binds to tRNA, if incorrect the bond is hydrolyzed
77
tRNA wobble
codons differing in the 3rd wobble position may code for the same tRNA/amino acid due to degeneracy genetic code
78
Protein Synthesis - Initiation
GTP hydrolysis, eIF help assemble 40S with initiator tRNA and are released when mRNA and 60S assemble
79
2nd step of protein synthesis
Elongation
80
A site
for incoming aminoacyl-tRNA (except for methionine)
81
P site
rRNA catalyzes peptide bond formation, transfers growing polypeptide to AA in A site growing peptide
82
E site
hold empty tRNA as it exits
83
Trimming
Post translational modification | removal of N or c terminal propeptides from zymogen to make mature protein
84
Covalent Alterations
Post translational modification | phosphorylation, glycosylation, hydroxylation, methylation, acetylation, and ubiquitination
85
Chaperone Protein
Intracellular protein involved in facilitating and/or maintaining protein folding
86
Heat Shock Protein
Ex of Chaperone protein, in yeast | HSP60, expressed at high temperatures to prevent protein denaturing and misfolding
87
World's shortest Joke: 2 women were sitting quietly
False. Your Penis.

First Aid Biochemistry (5 decks)

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