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genetics > Exam 3 > Flashcards

Exam 3 Flashcards

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Biology 101 flashcards
1
Q

genotype

A

what genetic info u have

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2
Q

phenotype

A

what traits you express

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3
Q

genetic information flow (central dogma)

A

DNA (nucleic acids) –> RNA (amino acids) –> protein

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4
Q

what contains all the info needed to transcribe DNA into mRNA

A

a gene!

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5
Q

translation of start vs stop codon

A
  • start codon is translated and found within the transcribed region
  • stop codon is not translated and is found outside the amino acid sequence (not encoded within the protein)
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6
Q

+1 nucleotide

A

(indicated often with an arrow)
- indicates the transcription start site and first nucleotide to be transcribed

*not necessarily before the AUG start codon

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7
Q

coding versus template strand

A

coding 5’ to 3’
template 3’ to 5’

see the codons within the coding strand (look for ATG)

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8
Q

what direction is RNA synthesized?

A

5’ to 3’ direction of the strand being built

(antiparallel to its complementary strand of DNA)

TEMPLATE = ANTIPARALLEL
CODING = CODONS

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9
Q

gene sequences written/read convention

A

gene sequences are written/read from 5’ to 3’ of the coding strand

*for a given gene, only 1 strand serves as a template

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10
Q

different genes have different ______

A

directions of transcription

this is bc different strands of dsDNA are used as the template for different genes (might be coding for one gene but template for another)

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11
Q

RNAP binds ______ to the promoter

A

upstream and moves downstream toward the rest of the gene

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12
Q

cis and trans elements purpose

A

recruit RNA polymerase to a gene

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13
Q

cis elements

A

regions of DNA that are required for gene expression/regulation

*part of the same molecule as the gene(s) they regulate!

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14
Q

trans elements

A

diffusible molecules (usually proteins) that bind cis elements

*separate molecules from the genes they regulate!

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15
Q

sigma subunit

A

key trans-factor that helps RNAP associate with promoters

in prokaryotes

many subunits functions together as 1 enzyme

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16
Q

consense sequences

A

a sequence of DNA having similar structure and function in different organisms.
(same sequence in the same location)

-10 and -35 consensus sequences are found in nearly all bacterial promoters

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17
Q

-35 consensus sequence

A

TTGACA

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18
Q

-10 consensus sequence

A

TATAAT

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19
Q

differences in euk. cis/trans factors (3)

A

1) no sigma subunit
2) different consensus sequences (TATA box most common)
3) additional cis-reg. elements besides promotor (enhancer/silencer) common. Enhancer often required!

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20
Q

termination sequence in prokaryotes

A

IS transcribed

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21
Q

termination mechanism of transcription

A

hairpin/stem loop
- complementary base pairing with itself

  • strong C-G bonds hold structure together causing the stalling of RNAP
  • When stalling occurs, the weak AU bonds cannot hold mRNA and DNA complex together
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22
Q

Rho protein

A

protein that induces the unwinding of RNA/DNA complex

-transcription termination of prokaryote

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23
Q

splicesome

A

snRNA and proteins

  • functions in recognizing introns and removing them
  • recognizes specific sequences in the DNA that will determine the sites of splicing
  • via BPing, the RNA component of splicesome recognizes the splice site sequences
  • found in nucleus
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24
Q

w/o CAP and Tail, RNA…..

A

would be degraded

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25
Q

If the protein were sufficient to catalyze the reaction, then what is the purpose of having RNA complexed?

A

recognition of the sequences that designate an intron

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26
Q

alternative splicing may generate…

A

2 or more types of mRNA from the same transcript

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27
Q

3 steps of translation

A

initiation, elongation, termination

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28
Q

translation initiation

A

complex of the ribosome, first charged tRNA, mRNA

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29
Q

translation elongation

A

peptide bonds formed as charged tRNAs bring appropriate amino acids

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30
Q

translation termination

A

stop codons signal release factors and complex dissociates (@ A site)

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31
Q

Shine-Delgarno sequence

A
  • ribosome binding site
  • positions ribosomes by start codon
  • found only in prokaryotes
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32
Q

ribosomal peptidyl transferase

A

transfers the peptide in the P site to the amino acid in the A site

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33
Q

termination of translation occurs…

A

when a stop codon is reached and a release factor binds

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34
Q

dehydration synthesis reaction

A
  • catalyzed by ribosomes in order to form a peptide (covalent) bond between 2 amino acids
  • loss of a water molecule
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35
Q

polarity of peptide

A
  • having 2 distinct ends
  • polarity of monomer is preserved in the polymer
    (direction of coding and template in reference to mRNA)
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36
Q

translation builds peptides in what direction?

A

N to C
amino acid to carboxylic acid

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37
Q

open reading frames (ORFs)

A

indicate regions that could potentially encode for a protein
- sequence of codons within the same reading frame starting with 5’-AUG and ending with STOP-3’

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38
Q

mRNAs contain both….

A

translated and untranslated regions

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39
Q
  • the transcription initiation site (+1 site) is….
A

NOT the translation initiation site (AUG)

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40
Q

ORF rule of thumb

A

the longer the ORF, the more likely its a true protein-coding ORF

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41
Q

identifying ORFs

A

use coding strands that look like mRNA

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42
Q

steps for locating proteins (6)

A

1) locate potential start codons (ATGs in any direction if coding strand is unknown)
2) identify the ORFs by finding inframe STOP codons
3) Determine polypeptide length
4) Determine directionality
5) Determine mRNA sequence
6) Translate!

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43
Q

tRNAs

A

translate codons into amino acids
- speak both languages bc can bind to codons that are both complementary and antiparallel

-function is to base pair with the codon on a strand of mRNA during translation.

***ensures that the correct amino acid will be added to the growing polypeptide chain.

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44
Q

how many codons are there?

A

64

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45
Q

how many codons encode for amino acids?

A

61

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46
Q

writing conventions for codons and anticodons

A

5’-codon-3’
3’-anticodon-5’

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47
Q

aminoacyl-tRNA synthetase

A

enzyme that carries out the charging of the tRNA with its specific amino acid

  • attaches an a.acid to its tRNA
  • highly specific for a given amino acid and for a given tRNA
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48
Q

aminoacyl- tRNA product

A

charged tRNA

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49
Q

wobble pairing

A

allows for a single anticodon of a tRNA to interact with more than one mRNA codon

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50
Q

G at the 5’ end of the anticodon recognizes…

A

C or U at the end of mRNA codon

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51
Q

the flow of genetic info can vary…

A

from gene to gene

for the same gene in different contexts

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52
Q

why doesnt bacterium transcribe all of its genes all the time?

A
  • metabolize organisms
  • bacteria only produce the proteins needed for lactose metabolism when lactose is present
  • saves energy and resources only to transcribe/translate when a protein is needed
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53
Q

add (+) regulation with

A

activator

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54
Q

remove (-) regulation with

A

repressor

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55
Q

inducible

A

default state = OFF
- transcription turned ON

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56
Q

repressible

A

default state = ON
- transcription can be turned OFF

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57
Q

constitutive

A

always on
- expression even when there is no lactose around and the operon should be turned off

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58
Q

2 ways to induce a gene

A

1) add activator
2) remove repressor

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59
Q

prokaryotes tend to regulate gene expression at the level of…

A

transcription

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60
Q

polycistronic RNAs

A

mRNAs that code for more than one protein under the control of a single promoter. (share a promotor)

(prokaryotic only)

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61
Q

operon

A

group of prok. genes that share a promoter and get regulated and transcribed as one unit

(energy/resource saver)

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62
Q

5 components of the lac operon

A

Regulatory:
1) promoter (P)
2) operator (O)

Ensures Lac Y/Z expression:
3) LacI

Genes encoding metabolism proteins:
4) LacZ
5) LacY

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63
Q

promoter (p)

A

DNA site where RNA polymerase initially binds

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64
Q

operator (o)

A

the site where the repressor binds

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65
Q

LacI

A

gene that encodes the repressor protein

**gene itself is NOT part of the lac operon
- has its own promoter and its regulated seperately
- still relevant bc protein it encodes regulated the lac operon

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66
Q

LacZ

A

gene that encodes B-galactosidase, an enzyme that breaks down lactose into monosaccharides

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67
Q

B-galactosidase

A

enzyme that breaks down lactose into monosaccharides

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68
Q

LacY

A

gene that encodes permease, an enzyme that makes it easy for lactose to enter the cell

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69
Q

permease

A

an enzyme that makes it easy for lactose to enter the cell

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70
Q

it is only beneficial to transcribe lac operon components when…

A

lactose is present

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71
Q

repressor protein can bind to…

A

allolactose and the operator BUT NOT at the same time

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72
Q

Without lactose….

A

repressor protein binds to operator and RNA poly cannot pass
- transcription DOES NOT occur

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73
Q

With lactose…

A

allolactose binds to repressor protein and changes shape so that it cannot bind to the operator
- transcription DOES occur

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74
Q

allolactose will always…

A

be present under the presence of lactose

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75
Q

WT Lac operon is only transcribed when…

A

lactose is present to inactivate the repressor
INDUCIBLE (default off)
- adding lactose turns on transcription

**induces by removing (-) regulation; stops repressor from binding

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76
Q

2 different mutations that could prevent the lac repressor from binding to the operator…

A

Lac I-
Lac Oc

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77
Q

Lac I- mutation

A

changes the shape of the Lac repressor DNA binding domain
- prevents lac repressor from being made

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78
Q

Lac Oc mutation

A

changes DNA sequence (operator) that Lac repressor recognizes
- prevents lac repressor from binding

  • constitutive expression
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79
Q

Lac Is mutation

A

prevents binding of allolactose
- prevents transcription (default OFF)

*** uninduciable transcription

super repressor

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80
Q

Lac Z- mutation

A

produces nonfunctional B-gal protein
- cannot metabolize lactose

  • does not prevent transcription
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81
Q

Lac Y- mutation

A

produces a nonfunctional permease protein
- stop the metabolism of lactose as it will not be able to enter the cell without permease.

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82
Q

Lac I- and I+ relationship

A

Lac I- is recessive to Lac I+
- heterozygote is inducible, not constitutive
(Lac I+/I- => merozygote)

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83
Q

bacteria (haploid) can become….

A

partial diploids OR merozygotes by aquiring plasmids

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84
Q

repressors cis or trans?

A

trans (diffuse to operator)

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85
Q

I-O+Z+Y+/I+O+Z+Y+ phenotype

A

inducible

  • w/o lactose (still has one I+) so still produces repressor protein and BLOCKS trans.
  • w/ lactose, repressors cannot bind and trans. occurs
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86
Q

I+O+Z+Y+/I+OcZ+Y+ phenotype

A

constitutive
*mRNA produced only from the operon with Oc mutation in CIS

  • w/o lactose, repressors bind to one operator but not the other (some transcription)
  • w/ lactose, all repressors cannot bind to operators (NO transcription)
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87
Q

regulatory elements

A
  • controls expression of genes
  • directly influences whether RNAP transcribes a gene
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88
Q

if lactose metabolism genes are transcribed constitutively…what mutations could have caused such?

A
  • LacI- (repressor doesn’t work)
  • LacOc (operator no longer binds to repressor)
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89
Q

Lac Oc causes constiutive expression only when…

A

alleles are in cis not trans (on same DNA molecule)

DOMINANT (O+ will falil to rescue the constiutive phenotype)

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90
Q

effector lactose induces the lac operon by…

A

removing (-) regulation

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91
Q

effector cAMP induces the lac operon by…

A

adding (+) regulation

92
Q

e. coli prefers to metabolize…

A

glucose for carbon energy source

  • therefore, beneficial to transcribe lac operon only when glucose is absent
93
Q

CRP

A

trans-regulatory factor that binds the promoter and helps to recruit RNAP

  • w/o CRP, RNAP is inefficient for finding and binding to promoter (trans. levels LOW)
94
Q

cAMP

A

effector that causes allosteric changes to CRP to allow it to bind to the promoter

95
Q

cAMP levels are ____ when glucose levels are _____

A

HIGH — LOW

96
Q

bacterial growth in lactose and glucose

A
  1. metabolizes glucose for low level transcription
  2. runs out of glucose, changes gene expression, and plateaus
  3. metabolizes lactose instead for higher levels of transcription
97
Q

transcription of the lac operon is at its MAX when…

A

lactose is present and glucose is absent

98
Q

no glucose or lactose

A

no transcription

99
Q

both lactose and glucose present

A

medium transcription

100
Q

lactose absent and glucose present

A

no transcription

101
Q

catabolic pathway operons

A

inducible (break down)

102
Q

anabolic pathway operons

A

repressible (build up)

103
Q

why are anabolic and catabolic pathways repressible and inducible respectively?

A

anabolic = repressible
- waste to make enzymes needed to build something that is already abundant (auto ON)

catabolic = inducible
- waste to make enzymes needed to break something down that is not present (auto OFF)

104
Q

trp operon

A

controls the expression of tryptophan synthesis of genes (anabolic)

contains:
- trp promoter
- trp operator
- repressor protein binding to operator (trpR)
- structural genes for tryptophan biosynthesis (trpE/B/C/D/A)

105
Q

when tryptophan binds to trp repressor protein bound to operator…

A

transcription does not occur (operon is turned off)

  • repressible (auto ON)
  • adds (-) regulation)
  • anabolic operon repressed in the presence of their metabolic end products (turned off when end product formed)
106
Q

7 types of gene expression

A

Regulation of:
1. chromatin remodeling
2. transcription
——– post-translational
3. splicing and processing
4. transport (out of cell)
5. degradation of mRNA
6. translational
7. protein modification

107
Q

all cells in an organism have….

A

the same DNA

  • same genes and same cis elements
  • BUT may express different trans elements
108
Q

what do differences in the expression of trans elements come from?

A

asymmetries of trans factors are established early in development, sometimes before fertilization

109
Q

the same gene in different cell types will have…

A

the exact same DNA (promoter and all regulatory elements)

110
Q

2 different genes in the same cell types will…

A

not be identical (different reg. elements)

111
Q

each cell is a different environment…

A

has different TFs that may or may not bind to cis reg. elements of different genes

112
Q

a gene will be off unless

A

cis-elements are accessible to bind to TF (by changes in chromatin structure)
- therefore can turn any gene on

113
Q

TFs cannot interact with….

A

cis-elements that are packed into inaccessible chromatin

114
Q

euchromatin

A

loosely packed
open
accessible
transcription ON

115
Q

heterochromatin

A

condensed
closed
inaccessible
transcription OFF

116
Q

chromatin accessibility can be regulated in 3 ways:

A
  1. histone modifications
  2. DNA methylation
  3. Nucleosome sliding/reorganization
117
Q

histone modifications

A
  • Acetylation increases accessibility
    — reduces (+) charge of histones by adding (-) charge to make less affinitive to (-)DNA
118
Q

methylation, ubiquitination, phosphorylation have….

A

variable effects on accessiblity

119
Q

DNA methylation

A
  • usually cytosine in eukaryotes
  • can result in more or less transcription unlike histone methylation

*most often associated with heterochromatin formation, decreased transcription, and gene silencing

120
Q

nucleosome

A
  • DNA and histone

Nucleosomes at the promoters of genes regulate the accessibility of the transcription machinery to DNA,

121
Q

interaction of cis and trans factors in a cell determines…

A

if/how a gene is transcribed

1) basal factors
2) TFs binding to enhancers/silencers
3) Tfs+cofactors

122
Q

basal factors

A

bind to promoters to recruit RNA poly to the gene

LOW LEVEL TRANSCRIPTION if only factor bound to DNA

123
Q

specific TFs bind to …..

A

enhancers or silencers

increases rate of transcription in addition to basal factors

124
Q

Physical interaction with the poly and TFs + their co-factors will…

A

increase or decrease the rate of transcription

125
Q

promoters are always…

A

directly upstream of the transcribed portion of the gene

126
Q

if u change orientation or location of promoter….

A

gene is NOT transcribed

127
Q

enhancers are always…

A

on the same chromosome (in cis) to genes they regulate
- nearby but can be far away (few hundred/thousand bp away on coding gene)

128
Q

if u change orientation or location of enhancer….

A

cis/trans factors can usually still complex and function normally

129
Q

silencer

A

type of enhancer that decreases transcription by binding to repressor proteins

130
Q

context-specific cis elements

A

context-specific if they interact with TFs present/active only in those specific contexts

(cell type, envt.)

131
Q

commonly responsbile for context-specific regulation of euk. genes?

A

enhancers/silencers

132
Q

can contain consensus sequences which interact with context-specific TFs?

A

promoters

133
Q

Hox genes

A

encode TFs that specify the formation of specific parts of the body

134
Q

ex/ front leg hox gene

A

front leg hox gene produces… front leg hox protein (TF) that binds….to cis regulatory elements on gene

135
Q

if body part in wrong spot….

A

body part will still be found noramlly in correct location

136
Q

having a head promoter on a leg hox gene (leg hox TF protein coding region)…

A

results in leg on head

— gene encodes for wherever the promoter directs expression to (INDUCTION)

137
Q

loss of function experiment clues for where a gene is expressed

A
  • function in development of body part
  • when during development/adulthood?
138
Q

flies lacking eyes

A

eyeless gene
ey-/ey-

139
Q

transgenic construct that shows which cells express the eyeless protein from embryo to adult stage

A

design: link eyeless cis elements to reporter gene (GFP)
methods: add this hybrid transgene to normal early embryo
results: look for GFP expression as flyes develop
- indicates where eyeless is being expressed and functioning!

140
Q

GFP

A

green fluorescent protein
- reporter gene we can see in living tissues

141
Q

transgene

A

a gene that has been transferred naturally, or by any of a number of genetic engineering techniques, from one organism to another.

can change phenotypes !!

142
Q

promoters

A

signal RNA poly to begin transcription
- gene sequences near the start site attract RNAP

143
Q

initiation of transcription

A
  • RNA poly binds to dsDNA at promoter
  • RNAP unwinds dsDNA to expose unpaired bases on template strand
144
Q

elongation of transcription

A
  • sigma subunit is released and RNAP looses its affinity for promoter and gains affiinity to DNA
  • mRNA extended 5’ to 3’ antiparallel to template strand
145
Q

termination of transcription

A

terminator RNA sequences signal the end of transcription
- forms hairpin loops
- releases both RNA polymerase and mRNA chain from DNA

146
Q

hairpin loops

A

ssRNA folds back on itself and comp. base pairs with C/G’s

147
Q

primary transcript

A

single strand of RNA resulting from transcription

148
Q

prok. vs euk. primary transcripts

A

P: primary transcript is the mRNA used for synthesis
E: primary transcript undergoes RNA processing before protein synthesis

149
Q

methylated cap

A

structure at the 5’ end of euk. mRNA formed by capping enzyme and methyl transferase

*efficient translation of mRNA into protein

150
Q

poly A tail

A

structure at the 3’ end of euk. mRNA consisting of 100-200 A residue
- stabilizes the mRNA
- uses ribonuclease and poly-A-polymerase

*efficient translation initiation

151
Q

5’ and 3’ untranslated regions (UTRs)

A

sequences located just after the methylated cap and before poly-A-tial
- encoded by exons and don’t include codons

152
Q

RNA splicing

A

deletes introns in euk. pre-mRNA and joins together adjacent exons to form mature mRNA

153
Q

spliceosome

A

a complex intranuclear machine that performs RNA splicing

contains small nuclear ribonucleoproteins (snRNPS)

154
Q

transfer RNA (tRNA)

A

small RNA adapter molecule that through complementary base pairing with codons in mRNA and places a specific amino acid at the correct position in a growing polypeptide chain at ribosome

*each tRNA carries 1 amino acid

155
Q

anticodon

A

3 nucleotides in tRNA molecules that recognize codons on mRNA by comp. BPing and wobble

*runs antiparallel to codon

156
Q

aminoacyl-tRNA synthetases

A

enzymes that catalyze the attachment of tRNAs to their corresponding amino acids, forming charged tRNAs

157
Q

charged tRNA

A

tRNA molecule to which the corresponding amino acid has been attached by aminoacyl-tRNA synthetase

  • bond between tRNA and AA generates energy for peptide bond formation
158
Q

wobble

A

1 tRNA == more than one codon
- 5’ end of anti-codon “wobbles” and can pair with multiple bases at 3’ of codon

159
Q

peptidyl transferase

A

the enzymatic activity of the ribosome responsible for forming peptide bonds between successive amino acids

160
Q

aminoacyl (A) site

A

site on a ribosome to which a charged tRNA first binds

161
Q

peptidyl (P) site

A

site on a ribosome to which the initiating tRNA first binds and the tRNAs carrying the growing polypeptide are located during elongation

162
Q

exit (E) site

A

occupied by tRNAs during period just after their disconnection from a.acids by action of peptidyl transferase and before release from ribosomes

163
Q

initiation codon

A

first codon to be translated and AUG at 5’ end of polypeptide

164
Q

Initiation

A

1st phase of translation for addition of amino acids during elongation

165
Q

ribosome binding site

A

region on prokaryotic mRNAs containing initiation codon and Shine-Delgarno box
— ribosomes bind with site to begin translation

166
Q

Shine-Delgarno box

A

sequence of 6 nucleotides (5’-AGGAGG-3’) in pro. mRNA that is one of two elements constituting a ribosome binding site

167
Q

promoters

A

signal RNA poly to begin transcription

168
Q

TSP initiation

A
  • RNA poly binds to the dsDNA at gene start; recognizes and binds to promoters with (subunit)
  • RNA poly unwinds part of the double helix to expose unpaired bases on the template strand
169
Q

TSP elongation

A
  • when sigma subunit is released, RNA polymerase loses its enhanced affinity for the promoter and regains its strong generalized affinity for any DNA
  • mRNA is extended 5’ to 3’ and moves antiparallel along the DNA template strand
170
Q

TSP termination

A

terminator RNA sequences signal the end of transcription
- form hairpin loops

171
Q

hairpin loops

A

ssRNA folds back on itself bc of comp. base piairng between different regions of the same molecule
- releases both RNA polymerase and RNA chain from DNA

  • C and G bond
172
Q

primary transcript

A

single strand of RNA resulting from transcript
- prokaryotes use primary
- eukaryotes use primary that has underwent RNA processing

173
Q

methylated cap

A

structure at the 5’ end of the euk. mRNA formed by capping enzyme and methyl transferase

  • efficient translation of mRNA into protein
174
Q

poly-A-tail

A

structure at the 3’ end of the euk. mRNA consisting of 100-200 A residues
- stabilizes mRNA with ribonuclease and poly-A-polymerase

  • efficient translation initation
175
Q

5’ and 3’ untranslated regions (UTRs)

A

sequences located just after the methylated cap and just before the poly-A-tail; encoded by exons and doesn’t include codons

176
Q

RNA splicing

A

deletes introns and joins together adjacent exons to form mature mrna in eukaryotes

  • splicesome performs RNA splicing and consists of small nuclear ribonucleoproteins (snRNPs)
177
Q

transfer RNA (tRNA)

A

RNA adapter molecule that places a specific amino acid at the correct position in a growing polypeptide chain at ribosome
*mediates translation of mRNA codons into amino acids

178
Q

anticodon

A

3 nucleotides in tRNA molecules that recognize codons on mRNA by comp. base pairing and wobble

*** codon and anticodons run antiparallel to one another

179
Q

aminoacyl-tRNA synthetases

A

enzymes that catalyze the attachment of tRNAs to their corresponding amino acids —- forming charged tRNAs

*** attach tRNAs to amino acids

180
Q

charged tRNA

A

tRNA molecule to which the corresponding amino acid has been attached by an amino acyl-tRNA synthetase

  • bond between the amino acid and tRNA contains energy that is used to drive peptide bond formation
181
Q

wobble

A
  • allows for one tRNA but more than one codon
  • 5’ end of anticodon (wobble position) can bind to multiple bases at 3’ end of codon
182
Q

peptidyl transferase

A

the enzymatic activity of the ribosome responsible for forming peptide bonds between successive amino acids

183
Q

aminoacyl (A) site

A

site on a ribosome to which a charged tRNA first binds

184
Q

peptidyl (P) site

A

site on a ribosome to which the initiating tRNA first binds and the tRNAs carrying the growing polypeptide are located during elongation

185
Q

exit (E) site

A

occupied by tRNAs during period just after their disconnection from amino acids by action of peptidyl transferase and before release from ribosomes

186
Q

initiation codon

A

first codon to be translated (AUG) part of the final protein

187
Q

TLN initiation

A

1st phase of translation for addition of amino acids during elongation

188
Q

ribosome binding site

A

region on prokaryotic mRNAs containing initiation codon and SD box

  • ribosomes bind with to begin translation
189
Q

Shine-Delgarno box

A

sequence of 6 nucleotides (5’-AGGAGG-3’) in pro.mRNA that is 1 of 2 elements constituting a ribosome binding site

190
Q

initiation factors

A

proteins that help promote the association of ribosomes, mRNA and initiating tRNA during 1st phase of translation

191
Q

TLN elongation

A

the ribosome continues to translate each codon in turn. - Each corresponding amino acid is added to the growing chain and linked via a bond called a peptide bond.

192
Q

elongation factors

A

proteins that aid in elongation of translation

193
Q

polyribosomes

A

a structure by the simultaneous translation of single mRNA molecule by multiple ribosomes

194
Q

termination

A

phase of translation that brings polypeptide synthesis to a halt

195
Q

release factors

A

proteins that recognize stop codons and help end translation

196
Q

polyprotein

A

polypeptide produced by a translation that can subsequently be cleaved by protease enzymes into 2 or more separate proteins

197
Q

posttranslational modifications

A

changes that occur to a polypeptide after translation has been completed

198
Q

catabolic pathways

A

metabolic pathways by which complex molecules are broken down
— inducible regulation

199
Q

anabolic pathways

A

metabolic pathways for the synthesis of complex molecules from simplier ones
— repressible regulation

200
Q

induction

A

the process by which a signal causes expression of a gene

201
Q

inducer

A

a small molecule that causes transcription from a gene
— stimulates the production of protein

202
Q

allolactose

A

inducer of the genes for lactose utilization

203
Q

repressor

A

binds to the operon’s operator

204
Q

inducer

A

binds to the repressor and prevents it from binding to the operator when present

205
Q

allosteric proteins

A

protein that undergoes a reversible change in conformation when bound to another molecule (inducer allolactose)

206
Q

constitutive mutants

A

strains in which certain gene products are made all the time (irrespective of environmental conditions)

ALL THE TIME

207
Q

operator site

A

short DNA sequence near a promoter that can be recognized by a repressor protein; binding of repressor to the operator blocks transcription of the gene

208
Q

lacI+ is ______ to LacI-

A

dominant to lacI- in trans

209
Q

lacIs is _________ to LacI+

A

dominant to lacI+ in trans

210
Q

RNAP I

A

transcribe genes that encode major RNA components of ribosomes (rRNAs)

211
Q

RNAP II

A

transcribes genes that encode proteins

212
Q

RNAP III

A

transcribes genes that encode tRNAs/other small noncoding RNA molecules

213
Q

enhancer

A

cis-acting regulatory element that regulates from nearby promoters
— function by acting as binding sites for TFs and are responsible for spatiotemporal specificity of transcription

214
Q

activator

A

TF that binds to specific DNA seq. with enhancer elements (CpG islands) and increases the level of transcription of a nearby promoter

215
Q

co-activators

A

protein that binds to a transcriptional activator and plays a role in increasing transcription levels

216
Q

H. acetyltransferases (HATs)

A

enzymes that acetylate histone tails lysines resulting in open chromatin
— favors gene expression by clearing promoters of nucleosomes

217
Q

H. methyltransferase (HMTs)

A

enzymes that methylate histone tail lysines and arginines and thereby affecting chromatin structure

218
Q

H. deacetylase

A

enzyme that removes acetyl groups from histone tail lysines

219
Q

H. demethylase

A

enzymes that removes methyls from histone tail lysines

220
Q

do prokaryotes undergo chromatin remodeling?

A

NO
lack histones

221
Q

trans vs cis mutations

A

cis mutations affect the plasmid it is on…not both
- trans elements can work in both plasmids if one is mutated

222
Q

if promoter is mutated…

A

no other genes will function

223
Q

a super repressor can only repress if

A

it is bound to operator

224
Q

Oc is —– to I

A

epistatic
– masked the affects of I

225
Q

Can cell grow if lactose is its only carbon source?

A

no —– requires beta-galactosidase

genetics (5 decks)

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