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Microbiology > Microbial Genetics > Flashcards

Microbial Genetics Flashcards

(101 cards)

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1
Q

Define genetics

A

study of genes; how they carry information; how that info is expressed; how that info is replicated

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2
Q

Define chromosomes

A

made up of DNA and protein; contain genes

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3
Q

Define genes

A

segment of DNA that encodes for functional products ( ex. proteins)

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4
Q

Define genome

A

genetic information in the cell

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5
Q

Define genetic code

A

set of rules that determine how nucleotides sequence converted to amino acid to protein

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6
Q

Define DNA and the 2 essential functions

A

Genetic blueprint

1) stores genetic information that instructs the cells on how to make proteins ( indirectly plays a role in protein synthesis)
2) replicates and make a copy of itself; copy passed down to daughter cell

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7
Q

What is the central dogma

A

dna> rna> protein

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8
Q

Define gene expression

A

combo of transcription and translation

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9
Q

Descrine bacterial dna and chromosomes

A

single circular chromosome
dna and protein
no histone ( just histone like proteins)

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10
Q

Define short tandem repeats (STRs)

A

repeating sequences of noncoding DNA

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11
Q

What are the 2 transfers of genetic information

A

1) vertical gene transfer

2) horizontal gene transfer

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12
Q

Define vertical gene transfer

A

flow of genetic information from 1 generation to the next.

occur during reproduction from parent to offspring

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13
Q

Define horizontal gene transfer

A

specific to prokaryotes
the transfer of genes b/t cells of the same generation
transfer from the donor cell to the reciptant cell
allows for recombination cell or recombination chromosome
recombinant genetic information not same as parent

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14
Q

Define recombination

A

genetic information can be transferred b/t cells of the same generation

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15
Q

What does DNA replications result in

A

formation of 2 identical complete DNA molecules each having 1 new strand and 1 strand from the original DNA

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16
Q

Define DNA gyrase

A

enzyme that release strain in region

relaxes supercoiling ahead of the replication fork

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17
Q

Define DNA helicase

A

enzyme that seperate both strands. unwinds double stranded DNA

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18
Q

Define DNA polymerase

A

bring complementary nucleotide and bring it growing strand; check if correct nucelotide is attached; synthesizes DNA; proofread and repairs DNA

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19
Q

Define replication fork

A

structure that forms within the long helical DNA during DNA replication

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20
Q

Define semiconservative

A

replication of a nucleic acid in which one strand of each double helix is directly derived from the parent molecules

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21
Q

What direction does DNA polymerase add nucleotide

A

5 to 3 prime direction

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22
Q

What initiates dna polymerase

A

RNA primer

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23
Q

Leading strand is …

Lagging strand is…..

A

synthesized continuously

synthesized discontinuosly, creating okazaki fragments

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24
Q

What remove the RNA primers and what joins the Okazaki fragment

A

dna polymerase remove primers

DNA ligase join okazaki fragments

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25
What are the 6 steps at the DNA replication fork ( figure 7.13)
1) enzymes unwind the parental double helix 2) proteins stabilize the unwound parental DNA 3) The leading strand is synthesized continuously by DNA polymerase 4) the lagging strand is synthesized discontinously. Primase, an RNA polymerase, synthesized a short RNA primer, which is then extended by DNA polymerase 5) DNA polymerase digest RNA primer and replaces it with DNA 6) DNA ligase joins the discontinuous fragments of the lagging strand
26
Define DNA ligase
makes covalent bonds to join DNA strands; join Okazaki fragments and new segments in excision repair
27
Define RNA polymerase
copies RNA fromm a DNA template
28
Define primase
synthesize RNA primer
29
What direction is DNA replication in prokaryotes
bidirectional
30
Define DNA gyrase ( topoisomerase I) in prokaryote
release supercoiling
31
Define topoisomerase IV
seperate 2 loops
32
What are the 3 types of RNA
1) Ribosomal RNA ( rRNA) 2) Transfer RNA (tRNA) 3) Messenger RNA ( mRNA)
33
Define ribosomal rna
integral part of ribosomes | role in protein synthesis
34
Define transfer rna
transports amino acids during protein synthesis
35
Define messenger RNA
carries coded information from DNA to ribosomes
36
Describe transcription in prokayotes. What is needed and what direction does it go
- synthesis of complementary mRNA strand - RNA polymerase - promoter - terminator - proceeds in 5 to 3 prime direction
37
Define translation
mRNA is translated into the language of proteins
38
Define codon. How many are there total? How many are sense and how many are nonsense?
``` group of measured RNA that code for amino acid 64 total codons 61 sense codons- 20 amino acids 1 start codon 3 nonsense codons ```
39
What is the start codon
AUG
40
What are the 3 stop codons
nonsense codon | UAA,UAG,UGA
41
Where does translation occur
ribosome
42
What type of codon is tRNA considered
anticodon
43
What are the 3 steps involved in translation
1) initiation 2) elongation 3) termination
44
On the ribosome what are the 3 binding sites for tRNA
A site P site E site
45
What are the 3 steps in transcription in eukaryptes
1) in the nucleus, a gene composed of exons and introns is transcribed to RNA by RNA polymerase 2) processing involved snRNPs in the nucleus to remove the intron-deprived RNA and splice together the exon-derived RNA into mRNA 3) After further modification, the mature mRNA travels to the cytoplasm where it directs proteins synthesis
46
Define exon
code for proteins
47
Define introns
do not code for proteins
48
Define small nuclear ribonucleoproteins ( snRNPs)
splice exons together
49
Define constitutive genes
expressed at a fixed rate not under control ex. enzymes involved in glycolysis
50
Define inducible genes ( repressible genes)
control mechanism-induction and repression regulates transcription of mRNA these genes are only expressed as needed
51
What is the the purpose of the operon model of gene expression
in bacteria it is a genetic regulatory system | set of operator,promoter, and structural genes
52
What is the structure of operon
operon consists of the promoter and operator sites and structural genes that code for the protein
53
Define promoter
segment of DNA where RNA polymerase initiates transcription of structural genes
54
Define operator
segment of DNA that controls transcription of structural genes
55
Define structural genes
regions of DNA that codes for the specific protein
56
Define mutation
a permanent change in the base sequence of DNA | may be neutral, beneficial or harmful
57
Define mutagens
a agent that cause mutations | can be anything physical/ chemical
58
Define spontaneous mutations
occur in the absence of a mutagens
59
What are the 2 types of mutations
point mutations | frameshift mutations
60
Define point mutation
base substitution | change only one base pair
61
What are the 3 sub types of point mutations
silent mutations missense mutations nonsense mutation
62
Define silent mutations
normal protein | does not change amino acid sequence b/c many codes code for the same amino acid
63
Define missense mutation
faulty proteins | amino acid is changed
64
Define nonsense mutations
``` incomplete protein results in stop codon stop codon ( UAA,UAG,UGA) ```
65
Define frameshift mutation
insertion or deletion of one or more nucleotide pairs | shifts the translational " reading frame"
66
What are 2 types of mutagens
1) chemicals | 2) radiation
67
Describe chemical mutagens and 2 examples
nucleotide base analogs that replace nucleotides resemble nucleotide exp: bromouracil resembles thymine aminopurine resembles adenine
68
What chemicals react with DNA
``` nitrous acid ( adenine to bind to cytosine) we can make antimicrobial agent ```
69
What are the 2 types of radiation
1) Non-ionizing | 2) ionizing
70
Describe non-ionizing ( UV radiation)
pyrimidine dimers
71
Describe ionizing ( xray, cosmic rays, gamma rays)
ionize water and produce free radicals | oxidize nucleotides and breaks sugar phosphate backbone
72
What is the frequency of mutation
1 in 10 to the power of 9 replicated base pairs | mutagens increase rate to 1 in 10 to the 5th power
73
What are the 3 ways of DNA repair
1) proofreading 2) mismatch repair 3) repair of thymine dimers
74
Define proofreading as a form of dna repair
corrected by dna polymerase | reads newly added basepair
75
Describe mistmatch repair as a form of dna repair
exonuclease dna polymerase ligase
76
Describe repair of thymine dimers as a form of dna repair
``` nucleotide excision repair ( dark repair) direct repair ( ligth repair) visible light ```
77
Define dark repair
DNA polymerase and ligase
78
Define light repair
photolyase | activated by light
79
Define genetic recombination
exchange of genes between 2 dna molecules
80
Define crossing over of genetic material
2 chromospmes break and rejoin insertion of foreign DNA into the chromosome RecA protein: does the joining
81
What 2 process does crossing over occur due to
1) vertical gene transfer | 2) horizontal gene transfer
82
Define vertical gene transfer
from organism to offspring
83
Describe horizontal gene transfer
from cells to same generation
84
What are the 3 types of horizontal genetic transfer in bacteria
1) transformation 2) conjugation 3) transduction
85
Define transformation
genes transferred from 1 bacteria to another as " naked" DNA
86
What are the 3 steps in transformation
1) receipient cells take up donor DNA 2) donor DNA aligns with complementary bases 3) recombination occurs between donor dna and recipient dna
87
Describe conjugation
plasmids transferred from 1 bacterium to another special plasmid- F factor F+ cells and F- cells
88
What is required in conjugation
require cell to cell contact gram negative-sex pili-projection from the donor's cell surface gram positive- sticky surface molecules
89
Why does antibiotic resistence occur
becuase of conjugation | b/c plasmid can only be transferred by conjugation
90
Describe transduction
DNA is transferred from a donor cell to a recipient cell via bacteriophage bacteriophage or phage-virus that infects bacteria
91
What are the 2 types of transduction
1) Generalized transduction | 2) specialized transduction
92
Define generalized transduction
random DNA packaged inside the phage and transferred
93
Define specialized transduction
specific bacterial genes are packaged inside the phage and transferred ex. toxins
94
What are the 5 steps of transduction
1) a phage infects the donor bacterial cell 2) phage DNA and proteins are made and the bacterial chromosomes is broken into pieces 3) occasionally during phage assembly,pieces of bacterial DNA are packaged in a phage capsid. then the donor cell lyse and release phage particle containing bacterial dna 4) a phage carrying bacterial DNA infects a new host cell, the recipient cell 5) recombination can occur,producing a recombinant cell with a genotype different from both the donor and recipient cells
95
Describe plasmids
self-replicating circular pieces of DNA often code for proteins that enhances the pathogenicity of a bacterium 1-5% the size of a bacterial chromosome
96
What are the 2 types of plasmids
1) conjugative plasmids | 2) dissimilation plasmids
97
Define conjugative plasmids
carries genes for sex pili and transfer of the plasmids
98
Define dissimilation plasmids
encode enzymes for the catabolism of unusal compounds
99
Define resistance factors (R factors)
encode antibiotic resistance ex. mercury resistance,sulfonamide resistance,streptomycine resistance chlormphenicol resistance, tetracycline resistance
100
Define transposons
small segments of DNA ( chromosome of plasmids) can move from one region of DNA to other contain insertion sequence (IS) code for transposases complex transposons carry other genes ( antibiotic resistance genes, toxin production genes)
101
Define transposases
cuts and reseals DNA

Microbiology (16 decks)

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