Chapter 7 Microbial Genetics Flashcards
1
Q
DNA
A
deoxyribonucleic acid
-encodes the genetic instructions used in the dvlpt and functioning of all known living organisms and many viruses
2
Q
Genetics
A
the study of inheritance and inheritable traits as expressed in an organisms genetic material
3
Q
Genome
A
- entire genetic complement of an organism
- includes its genes and nucleotide sequence
4
Q
Phosphodiester bonds
A
covalently bonded pentose molecules that connects the sides of the DNA ladder
-strong
5
Q
Nitrogenous bases
A
Adenine
Thymine
Guanine
Cytosine
6
Q
Complementary Bases
A
Adenine-Thymine/Uracil
Guanine-Cytosine
7
Q
Prokaryotic Genome
A
- Nucleoid: circular DNA
- plasmids
- RNA + ribosomes
- haploid
8
Q
Haploid
A
single chromosome copy
-one copy of each genes
9
Q
Plasmids
A
- small circular pieces of DNA that replicate independently
- separate from nucleoid
- not essential for normal metab, growth, + reproductions
- survival advantage
10
Q
types of Plasmids
A
1 fertility factors
2 resistance factors
3 bacteriocin factors
4 virulence plasmids
11
Q
Fertility Factors Plasmids
A
ability to produce sex pilus
12
Q
Resistance Factors Plasmids
A
R factors,
antibiotic resistance
13
Q
Bacteriocin Factors Plasmids
A
toxins produced by bacteria to inhibit growth of other closely related bacteria
14
Q
Virulence Plasmids
A
code of virulence factors
15
Q
DNA replication
A
- generates a complementary structure of the 2 strands of DNA
- semiconservative
- anabolic polymerization process
16
Q
Process of Bacterial DNA replication
A
- begins at origins site
- DNA polymerase replicates DNA from 5’ to 3’
- Strands are antiparallel new strands are synthesized differently
- -leading strand is synth continuously
- -lagging strand is synth discontinuously
17
Q
Genotype
A
set of genes in the genome
-genotype determines phenotype
18
Q
Phenotype
A
physical features and functional traits of the organism
19
Q
Gene Function
A
- TRANSCRIPTOIN
- TRANSLATION
- CENTRAL DOGMA OF GENETICS
20
Q
TRANSCRIPTION
A
information in DNA is copied as RNA
21
Q
TRANSLATION
A
polypeptides are synthesized from RNA
-participants: mRNA, tRNA, ribosomes+ rRNA
22
Q
Central Dogma of Genetics
A
- DNA is transcribed to RNA
- RNA is translated to form polypeptide
23
Q
transcription + translation in bacteria
A
cytoplasm
-coupled: transcrip+translat happen at the same time
24
Q
3 steps of Transcription
A
1 initiation
2 elongation
3 termination
- all stages require additional protein factors
- initiation + elongation require energy (GTP)
25
transcription + translation in bacteria
- occurs in cytoplasm
| - coupled: transcrip+translat happen at the same time
26
Nucleoid
- prokaryotic version of nucleus
| - circular DNA
27
transcription in eukaryotes
- RNA transcription occurs in nucleus
- -3 types of RNA polymerase, numerous transcription factors
- mRNA is processed before translation
28
where is the location of DNA in prokaryotes
in nucleoid of cytoplasm and in plasmids
29
histones are found in_____
| bacteria, archaea, or eukarya
histones are found in archaea and eukarya
30
type of nucleic acid in bacteria
circular or linear dsDNA
31
semiconservative
-new DNA is composed of 1 original + 1 daughter
32
anabolic polymerization process
- requires monomers + energy (ATP)
| - deoxyribonucleotides (dGTP) serve both functions
33
Leading Strand
- continuous synthesis
| - creating 5' to 3' starting on 5'
34
Lagging strand
- discontinuous synthesis
| - creating 5' to 3' starting on 3'
35
Key differences w eukaryotic DNA replication
- uses 4 DNA polymerase
- thousands of replication origins
- shorter Okazaki Fragments
36
Codon
3 base pairs that translates into a peptide
37
mRNA
-copy of recipe/original DNA
38
rRNA
-codes for ribosomes
39
tRNA
-chef helpers
40
RNA polymerase
makes RNA, uses Uracil instead of thymine
41
eukaryote vs prokaryote ribosomes
```
prokaryote = 70s ribosome (50s+30s subunits)
eukaryote = 80s ribosome (60s+40s subunit)
```
pro is smaller than eu ribosomes
42
single prokaryotic mRNA can code for ______
-several polypeptides.
43
Regulation of Genetic Expression
- bacteria adapt to changes in their surroundings and regulate which genes they need to turn on/off
- genes are transcribed and translated when cells need them
- bacteria regulate expression of many genes based on food sources
44
Quorum sensing
- regulates production of some proteins based on food sources available
- allows cells to conserve energy
45
Prokaryotic Operons
-regulates genetic expression
46
2 types of prokaryotic operons
1 Inducible Operons
| 2 Repressible Operons
47
Inducible Operons
-must be activated by inducers
ex) lactose operon-
presence of lactose turns the genes for lactose digestive enzymes on
48
Repressible Operons
-are transcribed continuously until deactivated by repressors
ex) tryptophan operon
presence of tryptophan turns the tryptophan synthesis enzyme off
49
Genetic Mutation
- change in nucleotide base sequence of a genome
- rare
- almost always deleterious
- rarely leads to a protein that improves ability of organism to survive
50
types of Mutation
1 Point Mutation
| 2 Frameshift Mutations
51
Point Mutations
- one base pair is affected
| - substitutions
52
Frameshift Mutations
-nucleotide triplets after the mutation are displaced
-creates a new sequence of codons
ex)
OG: AATTCC
Frameshift: AA[G]TTC
53
Mutagens
- things that generate mutations in genes
| ex) radiation, chem mutagens, nucleotide-altering chems, and frameshift mutagens
54
Radiation
- ionizing and non ionizing radiation
- type of mutagen
ex) UV light -wavelengths of UV disrupts the DNA
55
chemical mutagens
- nucleotide analogs: disrupts DNA and RNA replication
| - carcinogen
56
nucleotide-altering chemicals
- type of mutagen
- alter structure of nucleotides
- result in base-pair substitutions and missence mutations
- disrupts in DNA or RNA
- carcinogen
57
frameshift mutagen
-result in nonsense mutation
58
4 examples of mutagens
1 radiation
2 chem mutagen
3 nucleotide-altering chemicals
4 frameshift mutagen
59
frequency of mutations
1 in every 10million genes contains an error
- mutagens increase the rate by a factor of 1,000x
- many of mutations stop transcription or code for nonfunctional proteins
60
DNA repair mechanisms
- repair pathways exist so that we can correct the damage and repair the DNA
- in humans, environmental factors and UV result in nearly 1million individual molecular lesions per day
61
2 DNA repair pathways
1 LIGHT repair pathway
| 2 DARK repair pathway
62
Mutants
descendants of a cell that does not repair a mutation
63
Wild Type
cells normally found in nature
64
Methods to recognize mutants
1 Positive Selection
2 Negative (Indirect Selection)
3 AMES test
65
Genetic Recombinant
-exchange of nucleotide sequence occurs often bw homologous sequence
66
Recombinants
cells with DNA molecules that contain new nucleotide sequences
67
Vertical Gene Transfer
passing of genes to the next generation
68
Horizontal Gene Transfer
-donor cell contributes part of genome to recipient cell
69
4 types of Horizontal Gene Transfer
1 Transformation
2 Transduction
3 Conjugation
4 Transposon
70
Transformation Horizontal Gene Transfer
- recipient takes up the DNA from the environment
- cells that take up DNA are competent
- -- results fr alterations in cell wall and cytoplasmic membrane that also DNA to enter cell
71
Transduction Horizontal Gene Transfer
- transfer of DNA from 1 cell to another via REPLICATING VIRUS
- virus must be able to infect both donor and recipient cells
- BACTERIOPHAGE
72
Bacteriophage
virus that infects bacteria,
| replicates using bacterial organelles, and then lyses
73
Conjugation Horizontal Gene Transfer
- genetic transfer requires physical contact bw donor and recipient cell
- donor cell remains alive
- mediated by CONJUGATION (SEX) PILI
74
5 types of RNA
```
RNA primers
mRNA
tRNA
rRNA
regulatory RNA
```
75
Transposon
segments of DNA that moves from one location to another in the same/different molecule
-results from a type of frameshift insertion (transposition)
76
2 types of Transposons
1 simple transposon
| 2 complex transposon
77
AMES test
- used to determine mutants or the mutagenic potential of chemicals/microbes
- cells are mixed w suspected mutagenic chemical; then check to see if mutations have occured
78
AMES test
- used to determine the mutagenic potential of chemicals/microbes
- also determines mutants
79
Frederick Griffith Test
- demonstrated exchange of DNA via transformation
| - proved heredity of DNA
80
Promoter
part of the genes where transcription is initiated
81
3 processes that need to occur before eukaryotic mRNA can be translated
-capping, polyadenylation, + splicing
82
Methylation
adding a methyl group to dna from restricting enzymes
83
Light Repair
-DNA repair for pyrimidine dimer with visible light
84
Dark Repair
-DNA repair for pyrimidine dimer by removal of section w dimer. then DNA polymerase
85
Pirimidine
thymine or cytosine dimers.
| forms covalent bond and prevents hydrogen bonding
86
AUG
start codon and methionine
