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MCB2004 > L10: Microbial Genetics > Flashcards

L10: Microbial Genetics Flashcards

(74 cards)

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1
Q

the “central dogma” of molecular biology

A

genetics

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2
Q

genetics

A

the science of heredity: what genes are, how they carry information, how that info is expressed, and how genes are replicated

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3
Q

vertical gene transfer

A

the passing of genes to progeny (offspring)

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4
Q

gene expression

A

process of a gene becoming functional
DNA to protein

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5
Q

what are the 3 steps of gene expression?

A

replication (DNA doubles)
transcription (DNA to RNA)
translation (RNA to protein, ribosome)

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6
Q

genome

A

all the genetic material in a cell; all organisms have one

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7
Q

chromosomes

A

structures containing DNA that physically carry hereditary information; they contain genes

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8
Q

gene

A

a segment of DNA that encodes a functional product (usually a protein)

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9
Q

genomics

A

the molecular study of genomesgen

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10
Q

genotype

A

the genes of an organism

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11
Q

phenotype

A

the expression of an organism’s genes

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12
Q

DNA is a polymer of the nucleotides: adenine, thymine, cytosine, and guanine, which are…

A

dATP
dTTP
dCTP
dGTP

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13
Q

DNA is the genetic material of _____ cells

A

all

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14
Q

the backbone of DNA is the…

A

deoxyribose-phosphate

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15
Q

strands of DNA are held together by ________ between base-pairs of AT and GC

A

hydrogen bonds

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16
Q

DNA strands are _________ in direction

A

antiparallel

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17
Q

TRANSCRIPTION (eukaryotes): step 1?

A

starting at an RNA primer, DNA polymerase copies DNA in the 5’ to 3’ direction

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18
Q

TRANSCRIPTION (eukaryotes): step 2?

A

leading strand synthesized continuously
lagging strand synthesized discontinuously

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19
Q

TRANSCRIPTION (eukaryotes): the lagging strand comprises…

A

Okazaki fragments

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20
Q

TRANSCRIPTION (eukaryotes): Okazaki fragments

A

segmented pieces of the lagging strand in the 3’ to 5’ direction since DNA polymerase can only go in the 5’ to 3’ direction

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21
Q

TRANSCRIPTION (eukaryotes): step 3?

A

RNA primers are removed and Okazaki fragments are joined together by DNA ligase

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22
Q

TRANSCRIPTION (eukaryotes): step 4?

A

the energy comes from cutting the outermost 2 phosphate groups off of each nucleotide as it is added to the growing DNA chain

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23
Q

TRANSCRIPTION (eukaryotes): step 5?

A

stops when DNA polymerase reaches the terminator sequence on DNA

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24
Q

cellular organisms have ________ w/ proofreading abilities, so mutation rate is low under most conditions

A

DNA polymerase

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25
DNA replication is ___________, meaning that each new DNA has 1 old and 1 new strand
semiconservative
26
bacterial DNA replication differs from eukaryotic DNA replication in the sense that...
it is bidirectional
27
RNA
produced via transcription of DNA; contains ribose instead of deoxyribose, and is single-stranded
28
what are the 3 main types of RNA?
mRNA rRNA tRNA
29
mRNA
messenger RNA, which is the carrier of information between DNA and protein synthesis (translation)
30
rRNA
ribosomal RNA, which is structural RNA that comprises part of the ribosome (translation)
31
tRNA
transfer RNA, which brings amino acids to the ribosome to construct proteins (translation)
32
true or false: in bacteria, transcription and translation can occur simultaneously
true
33
operons
a unit made up of linked genes that regulate other genes responsible for protein synthesis
34
operons comprise...
promoters and operators
35
in bacteria, there can be up to ______ genes organized in operons
4 to 5
36
promoter
a specific DNA sequence located at the start of a gene that acts as a binding site for RNA polymerase, marking where transcription should begin
37
what is the difference between eukaryotic and bacterial promoters?
there can be several genes under the control of 1 promoter in an operon
38
the promoter controls/activates...
transcription
39
________ is often induced by a specific stimulus
transcription of an operon
40
transcription of a gene produces...
mRNA
41
transcription can also be induced by the removal of a ________from an operator
repressor
42
repressor
protein that acts as an on/off switch for gene expression
43
induction of an operon definition
the process where a group of genes within an operon are turned on (activated) in response to the presence of an inducer/operator
44
exons
coding regions of eukaryotic genes
45
introns
noncoding regions of eukaryotic genes
46
true or false: bacterial genes are split into exons and introns
false; they are NOT
47
in eukaryotes, after genes are transcribed to mRNA, the introns are _________ before the mRNA is translated by the ribosome
spliced
48
true or false: there is no splicing in bacteria
true; bacteria have no nucleus so splicing cannot occur
49
TRANSLATION: mRNA is translated into...
codons
50
codons
series of 3 nucleotides, which code for 1 amino acid
51
what is the start codon for translation of mRNA?
AUG - methionine (eukaryotes); formylmethionine (prokaryotes)
52
what are the stop codons for translation of mRNA?
UAA, UAG, and UGA (no amino acid to code for)
53
differences between bacterial and eukaryotic ribosomes allow us to use drugs that specifically affect...
bacterial ribosomes
54
why can mRNA be translated while still being transcribed from DNA in prokaryotes?
prokaryotic chromosomes are NOT in a separate compartment (nucleus)
55
what 4 things are required for translation?
amino acids ribosomes mRNA tRNA
56
mutation
a permanent change in the genetic material; can be neutral, beneficial, or harmful
57
mutagen
agent that causes mutations
58
spontaneous mutations
mutations that occur in the absence of a mutagen (i.e. RNA viruses)
59
example of a spontaneous mutation?
SARS-CoV2/COVID-19; mutates spontaneously at a rapid rate
60
base substitution (point) mutation
change in 1 base of DNA; is a type of silent mutation
61
missense mutation
base substitution that results in an amino acid change; is a type of point mutation
62
silent mutation
a change in a codon that does NOT result in a change of amino acid
63
nonsense mutation
base substitution that results in a "nonsense" stop codon; puts a stop codon in the wrong place
64
nonsense mutations cause...
a short, "truncated" and probably non-functional version of the protein
65
frameshift mutation
occurs when the 3-letter code is disrupted w/ an insertion or deletion of 1+ nucleotide pairs
66
what are the 4 main types of mutagens?
ionizing radiation UV rays chemicals DNA repair
67
ionizing radiation
causes the formation of ions that can react w/ nucleotides and the deoxyribose-phosphate backbone and form breaks in the DNA
68
UV rays
creates thymine dimers; covalently links the 2 bases together and causes mispairing
69
chemical mutagens
chemicals that damage DNA bases, become intertwined in the DNA double-helix, and cause mispairing of bases
70
DNA repair
multiple mechanisms for DNA repair, but they can't always keep up with the damage
71
translesion synthesis
a type of "last resort" DNA repair by adding a random nucleotide to create a "sloppy copy" of the original gene often causes mutation, but saves the live of the cell
72
spontaneous mutation rate
1 in 10^9 replicated base pairs 1 in 10^6 replicated genes
73
mutagens increase the mutation rate to...
1 in 10^5 or 1 in 10^3 per replicated gene; depends on the potency of the mutagen
74
Ames test
a bacterial mutation test used to measure the potency of a mutagen

MCB2004 (7 decks)

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