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Tri 2 - Microbiology > Ch. 7 > Flashcards

Ch. 7 Flashcards

(68 cards)

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1
Q

genetics

A

study of inheritance and inheritable traits as express in an organisms genetic material

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2
Q

genome

A

the entire genetic complement of an organism

including its genes and nucleotide sequences

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3
Q

structure of nucleic acids

A

polymers of nucleotides made of a phosphate, pentose sugar and nitrogenous base

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4
Q

prokaryotic chromosomes

A

nucleoid with DNA and associated proteins/RNA; haploid

plasmids

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5
Q

plasmids

A

small molecules of DNA that replicate independently; not essential for normal metabolism, growth, or reproduction; can confer survival advantages

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6
Q

types of plasmids

A

fertility factors
resistance factors
bacteriocin factors
virulence plasmids

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7
Q

fertility factors

A

instructions for conjugation

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8
Q

resistance factors

A

resistance to antimicrobial and heavy metal

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9
Q

bacteriocin factors

A

proteinaceous toxin

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10
Q

virulence plasmids

A

enzymes and toxins

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11
Q

eukaryotic chromosomes

A

typically have more than one chromosome per cell
are linear and sequestered within nucleus
diploid

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12
Q

extranuclear chromosomes of eukaryotes

A

DNA of mitochondria and chloroplasts; resemble that of prokaryotes; only code for about 5% of RNA/proteins
some fungi, algae, protozoa have plasmids

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13
Q

DNA replication

A

semiconservative (one original, one daughter)

anabolic polymerization requires monomers and energy (triphosphate deoxyribonucleotides serve both functions)

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14
Q

bacterial DNA replication

initial processes

A

bacterial DNA replication begins at the origin
DNA polymerase replicates DNA only 5′ to 3′
bidirectional
gyrases and topoisomerases remove supercoils
methylated

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15
Q

bacterial DNA strand synthesis

A

leading strand synthesized continuously

lagging strand synthesized discontinuously

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16
Q

DNA methylation

A 
control of genetic expression
initiation of DNA replication
protection against viral infection
repair of DNA
bacteria methylate adenine rarely cytosine
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17
Q

eukaryotic DNA replication differences

A

uses four DNA polymerases
thousands of replication origins
shorter Okazaki fragments
plant and animal cells methylate only cytosine bases

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18
Q

genotype

A

set of genes in the genome

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19
Q

phenotype

A

physical features and functional traits of the organism

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20
Q

transcription

A

information in DNA is copied as RNA

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21
Q

translation

A

process in which ribosomes use genetic information of nucleotide sequences to synthesize polypeptides

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22
Q

central dogma of genetics

A

DNA transcribed to RNA

RNA translated to form polypeptides

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23
Q

types of RNA transcribed from DNA

A 
RNA primers
messenger RNA (mRNA)
ribosomal RNA (rRNA)
transfer RNA (tRNA)
regulatory RNA (Interact with DNA to control gene expression)
ribozymes (RNA molecules function as metabolic enzyme)
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24
Q

prokaryotic transcription

A

occurs in nucleoid

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25
steps of transcription
initiation elongation termination all require protein factors, first two require energy (GTP)
26
transcriptional differences in eukaryotes
RNA transcription occurs in the nucleus, mitochondria and chloroplasts three types of nuclear RNA polymerases numerous transcription factors
27
mRNA processed before translation
capping polyadenylation splicing
28
participants in translation
messenger RNA transfer RNA ribosomes and ribosomal RNA
29
termination
release factors recognize stop codons; modify ribosome to activate ribozymes ribosome dissociates into subunits polypeptides released at termination may function alone or together
30
translation differences in eukaryotes
initiation occurs when ribosomal subunit binds to 5′ guanine cap first amino acid is methionine rather than f-methionine
31
regulation of genetic expression
most genes are expressed at all times, other genes transcribed and translated when cells need them (energy conservation) regulation of polypeptide synthesis: typically halts transcription can stop translation directly
32
nature of prokaryotic operons
an operon consists of a promoter and a series of genes | controlled by a regulatory element called an operator
33
inducible operons
must be activated by inducers | e.g. lactose operon regulates lactose catabolism
34
repressible operons
transcribed continually until deactivated by repressors | e.g. tryptophan operon regulates tryptophan synthesis
35
mutation
change in the nucleotide base sequence of a genome; rare event almost always deleterious rarely leads to a protein that improves ability of organism to survive
36
types of mutation
point mutations | gross mutations
37
point mutations
one base pair affected | substitution and frameshift mutations
38
gross mutations
include inversion, duplications, and transpositions
39
substitutaion
mismatching of nucleotides or replacement of one base pair by another
40
frameshift | insertion
addition of one or a few nucleotide pairs creates new sequence of codons
41
frameshift | deletion
removal of one or a few. nucleotide pairs creates a new sequence of codons
42
mutagens
radiation | chemical
43
radiation mutagens
``` ionizing (X rays, gamma rays) non ionizing (UV) ```
44
chemical mutagens
nucleotide analogs nucleotide-altering chemicals frameshift mutagens
45
nucleotide analogs
disrupt DNA and RNA replication
46
nucleotide-altering chemicals
result in base-pair substitutions and missense mutations | e.g. aspergillus produces aflatoxin which causes liver cancer
47
frameshift mutagens
result in nonsense mutations
48
mutation frequency
rare events otherwise organisms could not effectively reproduce mutagens increase rate by a factor of 10-1000 times
49
DNA repair
cells have numerous methods for repairing damaged DNA
50
categories of DNA repair
direct repair single-strand repair error-prone repair
51
error-prone repair
induced when DNA damage is extensive repair system of last resort SOS response in E. coli
52
mutants
descendants of a cell that does not repair a mutation
53
wild-type cells
cells normally found in nature
54
methods to recognize mutants
positive selection negative (indirect) selection ames test
55
genetic transfer
exchange of nucleotide sequences often occurs between homologous sequences
56
recombinants
cells with DNA molecules that contain new nucleotide sequences
57
horizontal gene transfer | prokaryotes
donor cell contributes part of genome to recipient cell
58
types of horizontal gene transfer
transformation transduction bacterial conjugation
59
transformation | horizontal gene transfer
one of conclusive pieces of proof that DNA is genetic material cells that take up DNA are competent; results from alterations in cell wall and cytoplasmic membrane that allow DNA to enter cell
60
generalized transduction | horizontal gene transfer
transducing phage carries random DNA segment from donor to recipient
61
specialized transduction | horizontal gene transfer
only certain donor DNA sequences are transferred
62
bacterial conjugation
1. donor cell attaches to a recipient cell with its pilus 2. pilus draws cells together 3. one strand of F plasmid DNA transfers to the recipient 4. recipient synthesizes a complementary stand to become an F+ cell with a pilus; donor synthesizes a complementary strand restoring its complete plasmid
63
transposons
segments of DNA that move from one location to another in the same or different molecule; contain palindromic sequences at each end
64
transposition
kind of frameshift insertion result | can move onto plasmids to be transferred to another cell
65
jumping transposons
move from one place to another on a DNA molecule
66
replicating transposons
may replicate while moving, resulting in more transposon in the cell
67
insertion sequences
simplest transposons | have no more than two inverted repeats and a gene for transposase
68
complex transposons
contain one or more genes not connected with transposition

Tri 2 - Microbiology (6 decks)

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