Exam 1 9/14 Nguyen Micro Flashcards
(107 cards)
1
Q
Central dogma
A
Dna to rna to protein
2
Q
Purines
A
A and G
3
Q
Pyrimidines
A
C, U, T
4
Q
A-T has ___ H bonds
A
2
5
Q
C-G has ___ H bonds
A
3
6
Q
Direction of transcription
A
5 to 3 prime
7
Q
Codons
A
each amino acid is defined by triplet code
8
Q
Start codon on DNA
A
ATG
9
Q
Start codon on RNA
A
AUG
10
Q
Stop codon DNA
A
TAA, TAG, TGA
11
Q
Stop codon RNA
A
UAA, UAG, UGA
12
Q
True or false: bacteria do not contain histones
A
True
13
Q
Merodiploid
A
Partial duplication of chromosome in cell; contains 2 copies of genes
14
Q
Virulent strains of Vibrio cholerae may contain:
A
2 chromosomes
1st = essential cellular functions, PAIs
2nd = some essential cell functions, plasmid genes
15
Q
DNA methylation in humans promotes formation of:
A
heterochromatin
16
Q
Histone acetylation promotes the formation of:
A
euchromatin
17
Q
Human genes may include what features?
A
- upstream repressor/enhancer sites
- promoter
- introns and exons
- distant enhancer
18
Q
True or false: bacteria does not contain mitochondrial DNA or introns
A
True
19
Q
Operon
A
composed of many genes controlled by a common promoter
20
Q
Cistron
A
coding gene within an operon
21
Q
Operons are generally _____
A
polycistronic
22
Q
Operons have a common _____ for transcription
A
terminator
23
Q
Operon promoter is recognized by:
A
RNA polymerase (initiates gene or cistronic transcription)
24
Q
Operator another name
A
Regulator
25
Positive control
Inducible
26
Negative control
Repressible
27
What is a benefit for bacteria to have operons?
Synthesize all related enzymes "together"; fast and efficient environmental adaptation
28
Constitutive expression examples in bacteria
Transpeptidase, NAG, NAM
29
Negative control operon example
Trp operon
30
Positive control operon example
Lac operon
31
Which operons are examples of regulated expression?
Trp and Lac operon
32
Trp operon is expressed by ____, because:
default; trp is often missing
33
Describe what happens when trp operon is on
1. repressor protein unable to bind DNA
2. polycistronic mRNA transcribed
3. trp A-E make tryptophan synthetase
34
Function of trp operon
Makes more tryptophan when concentration of tryptophan is low in the cell
35
If tryptophan is present in the environment, then:
tryptophan triggers repression
- tryptophan binds repressor protein
- tryptophan + repressor bind DNA
- blocks RNA polymerase so it cannot make mRNA
36
In lac operon, if glucose is low and lactose is available, then:
lac operon is expressed to make lactase
37
Transcriptional regulation of lac operon
not expressed by default, is inducible; repressor binds to operator so RNA Pol can't bind to promoter
38
In lac operon, when lactose is present:
1. allolactose protein binds to repressor, released from operator site on DNA
2. RNA Pol binds to promoter to allow transcription
39
Catabolite activator protein (CAP)
Glucose sensor
40
Hunger molecule
cAMP
41
E. coli makes ___ when low in glucose
cAMP
42
Alternative regulator of lac operon
CAP-cAMP
43
When CAP-cAMP binds to DNA:
increases transcription of lac operon
44
CAP acts as a:
lac operon repressor
45
When glucose is present, ____ cAMP
low
46
When glucose is low, ____ cAMP
high
47
Pathogenicity islands (PAIs)
selective advantage to virulent or pathogenic strains, can regulate many operons at one time
48
Binary fission
Splits into 2 cells
49
OriC
replication initiation site
50
Replication fork
Where dna is splitting
51
Topoisomerase
unwinds DNA
52
helicase
separates dna strands
53
RNA primase
makes rna primers
54
DNA polymerase
adds nucleotides
55
gyrase
supports elongation
56
Leading strand
adds nucleotides to 3' end
57
Lagging strand
cannot add nucleotides to 5' end, okazaki fragments have to be made
58
DNA ligase
replaces rna primer with dna, joins okazaki fragments
59
Genetic variation can be caused by:
mutation, gene transfer
60
Transition replacement
purine replaced with purine; pyrimidine switched with another pyrimidine
61
Transversion replacement
purine switched for pyrimidine
pyrimidine switched for purine
62
Types of mutations
deletion, insertion, inversion, translocation, replication slippage
63
replication slippage mutation
Slipped-strand mispairing
64
Tandem repeats
large number of repeats, forma a loop
65
Silent mutation
results in same amino acid
66
Nonsense
insertion of stop codon - may have partial protein function
67
Missense
results in different amino acid
68
Proofreading repair
done by DNA Polymerase - detects and replaces incorrect nucleotide in just made dna
69
Restriction endonucleases
excision repair/damage repair; defensive mechanism, creates palindromes, uses in genetic engineering
70
CRISPR
clustered regularly interspaced short palindromic repeats
71
Very precise gene editing tool
CRISPR
72
Cas
CRISPR associated protein
73
Cas function
guide recognizes and cuts specific dna strands
74
Prokaryotes SOS dna repair is used for:
extensive dna damage -- error prone
75
Mutation rate ____ during SOS repair
Increases; increases drug resistance
76
Gene transfer methods
conjugation, transduction, transformation, transposition
77
Conjugation
bacterial sex
78
Transduction
Viral infection
79
Transformation
taking foreign dna
80
Transposition
jumping genes
81
Plasmids r factor
Resistance
82
Plasmids f factor
Fertility
83
True or false: plasmids can be found in both gram + and - bacteria
true
84
Plasmid is located:
not on chromosome
85
Plasmids can be transferred between bacteria via
sex pilus
86
Plasmids multiply ___ of chromosome
Independently
87
Can plasmids be inherited by daughter cells?
Yes
88
Plasmids help bacteria confer
antibiotic resistance
89
F+
plasmid containing; donor; forms sex pilus
90
Donor and recipient of plasmid
Both F+
91
Plasmid F-factor transfer
1. double strand dna separate at OriT
2. rolling replication - both strands make complementary strands
92
Hfr
High frequency recombination cells - derivative of F+ cells
- when F plasmid becomes incorporated into the chromosome
93
R plasmid confers resistance to protect cells from:
heavy metals, enzyme attacks, antibiotics (confers antibiotic resistance)
94
Beta lactamase
Cleaves beta lactam ring, inactivates penicillin
95
Plasmids can have ___ gene to sequester iron
siderophore
96
Bacteriocin
inhibits growth of closely related species
97
Lytic pathway
virulent phages
98
Lysogenic pathway
Temperate phages, forms prophage where phage dna remains dormant; certain triggers can cause to go back to lytic phase
99
Phage encoded exotoxin genes
Host produces exotoxins that are controlled by phage genes, toxins released when cell lyses
100
Transformation summary
1. transfer of exogenous bacterial dna
2. taken up by competent cells
3. recombined with the recipient cell dna or as plasmid
101
Homologous recombination
break and recombine, can alter coding sequences and genes, usually within genera or genus
102
Transposable elements contain:
1. insertion sequences
2. transposon dna's
3. transposase enzymes
103
Transposase enzymes
endonucleases to cut and ligases to paste dna
104
Transposition causes genes to move from:
one dna location to another. requires little/no homology, can alter genes and coding sequences
105
Pathogenicity islands are different from operons in that:
biochemically unrelated but function synergistically
106
Other isolated genetic islands are separated by:
GC-rich regions
107
Fitness or persistence islands may code for:
survival traits - not strictly virulence factors (e.g. biofilm formation)
