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College > Genetics test 5 > Flashcards

Genetics test 5 Flashcards

1
Q

functions of protein macro level

A

form structures - hair, scales, feathers
glow to act as a signal between organisms
Be used to kill - rattlesnake venom

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2
Q

Functions of protiens within and between cells

A

Machines - DNA polymerase, ATP synthase, Dynein
Signals - Insulin, Oxytocin, Leptin
Structures - microtubules, actin, membrane channels

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3
Q

acidic amino acids

A

Non essential
negative charge
hydrophilic
ionic and hydrogen bonds

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4
Q

basic amino acid

A

lysine
positive charge
hydrophilic
ionic and hydrogen bonds

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5
Q

neutral polar amino acids

A

threonine
no charges

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6
Q

nuetral nonpolar amino acids

A

tryptophan
phenylalanine
valine
isoleucine
leucine
methionine
hydrophobic

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7
Q

start codon

A

AUG

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8
Q

Stop codon

A

UAA
UAG
UGA

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9
Q

amino acids are linked together via

A

peptide bonds

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10
Q

Protien structure language

A

a chain of amino acids is a peptide or polypeptide
one oe more chains together may be a protien
protiens have structure: primary, secondary, tertiary, and quartenary

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11
Q

Primary structure of protiens

A

order of amino acids in polypetide chain

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12
Q

secondary structure of protiens

A

regular folding of a single chain
maintained by weak bonds (hydrogen pairing)
ALPHA helix or BETA sheet

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13
Q

Tertiary structure of protiens

A

three-dimensional structure of an entire polypeptide chain

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14
Q

Quartenary structure of protiens

A

arragement of multiple polypeptides into a single multi-subunit complex

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15
Q

Structure of tRNA

A

75-90 nt long - different sequences
cloverleaf configuration
loop 2 contains anticodon
each tRNA binds one amino acid

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16
Q

anticodon

A

tRNA anticodon pairs with its complementary codon on the mRNA molecule
appropriate amino acid is inserted into the polypeptide

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17
Q

charging of tRNA

A

one ATP required
aminoacyl tRNA synthetase enzyme catalyzes reaction
molecules are chemically linked to proper amino acids
amino acids converted to active form - reacts with ATP to create aminoacyladenylic acid

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18
Q

Bacterial/prokaryotes ribosomes

A

70S = 50S (large) + 30S (small)
50 has 23S and 5S rRNA
30 has 165 rRNA
unit arranged as 5’–16S–23S–5S–3’
transcibed as single pre-rRNA transcript, but bound by ribosomal protiens and cleaved by enzymes co-transcriptionally to produce ribosomal complex
bacteria only have one RNA polymerase, so it also transcibes this RNA

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19
Q

Eukaryotic ribosomes

A

80S = 60S (large) + 40S
Large subunits have 28S, 5.8S and 5S rRNA
Small subunits contain 18S rRNA
Unit arranged as 5’–18S–5.8S–28S–3’
pre-rRNA is enzymatically cleaved by RNA pol III, the massive transcription from the tandem copies leads to nucleolus formation
The 5S rRNA is transcribed from a separate locus - RNA Pol I

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20
Q

ribosome site A

A

aminoacyl site
where the incoming charged tRNA binds

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21
Q

ribosome site P

A

aminoacyl site
where a tRNA bound to the growing polypeptide chain sits

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22
Q

ribosome site E

A

exit site
where a free uncharged tRNA preparing to exit the ribosome sits

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23
Q

shine dalgarno

A

relationship between start AUG and shine-dalgarno sequence
shine dalgarno binds to a complementary sequence in the 16S rRNA
shine-dalgarno sequence is located in the 5’ UTR of mRNA about 8-12 nts before the AUG start codon

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24
Q

prokaryotic initiation of translation

A

1) load mRNA onto small subunit
2) load first tRNA
3) add large subunit, kick out IF’s, hydrolyze GTP

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25
Q

Step 1 of prokaryotic initation of translation - load mRNA onto small subunit

A

Initiation factor-1 blocks A site
IF-3 blocks 50S attachment
helps mRNA binding to 30S
shine-delgarno sequence complementary to 16S rRNA in 30S subunit

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26
Q

Step 2 of prokaryotic initation of translation - load first tRNA

A

since A site is blocked and E site doesn’t exists, tRNA loads into P site
IF-2 brings a special fMET tRNA for iniation in prokaryotes

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27
Q

how are eukaryotic initation of translation different

A

IF’s = eIF’s and there are many more than 3
Initiator Met is NOT modified
no shine-dalgarno
Best model is scanning model for identifying start

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28
Q

Key points in the scanning model

A

eIF-4e is “cap binding protien’ (binds 5’ cap on mRNA)
the poly-a-tail loops around and is involved through association with eIF-4F and eIF-4G
the 40S subunit, bound to Met-tRNA
Met loads onto 5’ end and slides along looking for an AUG that is not a Kozak sequence

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29
Q

elongation

A

Once 70S initiation complex is formed, fMet-tRNA
fMEt is bound to AUG codon in the P site of the ribosome
1) Next charged tRNA loaded into the A site
2) peptide bond formation
3) translocation
4) repeat steps 1-3

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30
Q

elongation step 1

A

EF-Tu (elongation factor 2) TS and GTP/GDP are required to bring new tRNA’s to the ribosome for elongation

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31
Q

elongation step 2

A

peptide bond forms between the two adjacent amino acids, catalyzed by peptidyl transferase
The linked amino acids are attached to the tRNA in the A site, forming a peptidyl-tRNA

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32
Q

elongation step 3

A

the ribosome shifts doen one codon
the empty tRNA is ejected from the E site
the tRNA + growing chain shifts to P site, the A site is empty again

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33
Q

termination

A

1) stop codon is encountered
2) release factor (RF1) binds to stop codon
3) polypeptide chain is released
4) RF3-GDP binds causing RF1 relase. GTP replaces the GDP and GTP hydrolysis relases RF3
5) ribosome recycling factor (RRF) binds to A site
6) EF-G-GTP binds to ribosome. Hydrolsysis of GTP tp GDP causes translocation of the ribosome, putting RRF in the P site, and the tRNA in the E site
7) RRF relases the uncharged tRNA, EF-G then releases RRF, and the two ribosomal subunits dissociate from the mRNA

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34
Q

tetrapeptide

A

a polypeptide made up of four or more amino acids

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35
Q

N-terminus

A

Amino group

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36
Q

C-terminus

A

Carboxyl group

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37
Q

R-group

A

will differ based on the amino acid

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38
Q

a-carbon

A

carbon at the center of the amino acid

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39
Q

peptide bond

A

bond between amino acids

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40
Q

inducible enzymes

A

bacteria adapt to environment by producing inducible enzymes only when specific substrates are present

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41
Q

constitutive enzymes

A

enymes are continuously produced regardless of the chemical makeup of the environment

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42
Q

positive control

A

transcription occurs only when regulator molecule directly stimulates RNA production

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43
Q

negative control

A

genetic expression occurs unless shut off by regulator milecule

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44
Q

gene regulation - prokaryote

A

metabolic response to the environment

45
Q

gene regulation - eukaryote

A

cell-type specific gene expression
all cells have the same DNA but specific cells need to express specific genes depending on thier function
expression under certain conditions

46
Q

operons

A

genes coding for enzymes with similar functions organized in clusters with their regulatory sequences

47
Q

cis-acting

A

regulatory region on same strand
regulatory site determine if genes are transcribed into mRNA

48
Q

trans-acting elements

A

binding at cis-acting site regulates cluster negatively (turning off transcription) or positively (turning on transcription)

49
Q

Lac (lactose) operon

A

has three structural genes: lacZ, lacY, and lacA
all three genes transcribed as single unit
result in polycistronic mRNA

50
Q

cistron

A

part of nucleotide sequence coding for single gene

51
Q

In the presence of lactose

A

transciption occurs onyl when repressor fails to bind operator region
repressor is allosteric - reversibly interacts with another molecule, causes conformational change in shape and chemical activity

52
Q

Lac operon subject to negative control

A

repressor normally binds DNA sequence in operator region
inhibits RNA polymerase
represses transciption of strutual genes

53
Q

catabolite-activating protien (CAP)

A

helps activate expression of lac operon
able to inhibit expression in the presence of glucose
inhibition called catabolite repression

54
Q

cAMP: cyclic adenosine monophosphate

A

to bind to promoter, CAP must be bound to cyclic adenosine monophosphate
glucose inhibits activity of adenylyl cyclase, which catalyzes conversion of ATP to cAMP
prevents CAP from binding when glucose is present

55
Q

closed chromatin

A

inhibitory conformation (closed chromatin)
tight association of DNA with histones inhibits access to DNA protiens-affects transcription
chromatin structure must become “open” prior to transcription initation

56
Q

DNA methylation

A

type of chromatin modification
plays role in gene regulation: represses gene expression
methylation occurs most often: at 5 posistion cytosine

57
Q

Enhancers

A

located on either side of gene, some distance from gene or even within gene
increase rate of transcription
confer time- and tissue- specific gene expression

58
Q

silencers

A

repress the level of transcription initiation
acts as negative regulator of transcription
acts in tissue- or temporal- specific ways in gene expression

59
Q

transcription factors

A

promoters, enhancers and silencers act as binding sites for transcription factors
Activators
repressors

60
Q

activators

A

increase transcription iniation

61
Q

repressors

A

reduce transcription initiation

62
Q

coactivators

A

serve as bidge between activators and promoter-bound GTFs

63
Q

enhanceosomes

A

Large complexes of activators and coactivators that direct transcription activation

64
Q

repressor protiens

A

at silencer elements decrease rate of PIC assembly and RNA Pol II release

65
Q

introns

A

areas within a gene that are going to be ignored

66
Q

exons

A

areas within a gene that are going to be expressed

67
Q

type of mutation that changes the entire sequence of DNA following the mistake

A

frameshift mutation

68
Q

tRNA and mRNA are involved in

A

protien synthesis

69
Q

a mutation can chanve the _____ and be replicated when forming new cells

A

Genetic code

70
Q

DNA replication is

A

semiconservative

71
Q

after transcription, mRNA leaves the nucleus and attaches itself to a

A

ribosome

72
Q

________ carries amino acids to the site of protien synthesis

A

tRNA

73
Q

the bases are often abbreviated to _, _, _, and _

A

ACGT

74
Q

_____ joins the okazaki fragments

A

ligase

75
Q

unwound DNA

A

chromatin

76
Q

a mutation can be ______, beneficial, or harmful

A

neutral

77
Q

DNA polymerase replicates one stran ______ and one not

A

continuously

78
Q

A purine —> purine or pyrimidine —> pyrimidine mutation

A

transition

79
Q

A(n) _____ is a sequence of three bases in a tRNA molecule

A

anticodon

80
Q

Passed on from parents to offspring

A

trait

81
Q

_____ connect the bases

A

hydrogen bonds

82
Q

Part of a chromosome, passed on from parents to offspring

A

gene

83
Q

_____ adds nucleotides and checks to make sure the new copy
is correct

A

DNA polymerase

84
Q

Ribosomes are located on the _____

A

Endoplasmic reticulum

85
Q

Because it only makes 5’-3’, DNA polymerase makes little
sections for the other side called _____

A

okazaki fragments

86
Q

One base is placed incorrectly

A

substiution

87
Q

One base is added

A

insertion

88
Q

_____ creates a primer on the DNA strand by adding RNA
nucleotides

A

primase

89
Q

DNA is shaped like a twisted ladder, or ____

A

double heliex

90
Q

Mutations can be _____

A

inheritable

91
Q

In DNA, adenine pairs with _____

A

thymine

92
Q

One base is deleted

A

deletion

93
Q

A purine —> pyrimidine or pyrimidine —> purine mutation

A

transversion

94
Q

The message from the mRNA will be translated into an _____
sequence

A

amino acid

95
Q

A(n) _____ is a sequence of three bases that codes for an amino
acid

A

codon

96
Q

The sides of DNA are made of _____ and phosphate.

A

deoxyribose

97
Q

Transcription happens in the _____

A

nucleus

98
Q

DNA replication does not happen when the cell _____

A

divides

99
Q

DNA is _____

A

antipararallel

100
Q

A change that takes place in DNA

A

mutation

101
Q

A and G are both _____

A

purines

102
Q

RNA has _____ instead of thymine

A

uracil

103
Q

Translation occurs in the _____, specifically on the ribosomes

A

cytoplasm

104
Q

_____ contain nitrogen

A

nitrogen bases

105
Q

Transcription is the process of making _____

A

mRNA

106
Q

T and C are _____

A

pyrimidines

107
Q

_____ are made in the ribosomes

A

protiens

108
Q

Helicase _____ DNA

A

unwinds

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