Microbiology (BMSC 210) > MODULE 6 > Flashcards

MODULE 6 Flashcards

(84 cards)

Study These Flashcards
1
Q

what are mutations

A

random changes in DNA sequence overtime

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are 4 types of mutations

A

substitute
insert
delete
duplication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

genomes of bacterial cells are :
while viral genomes are:

A

double stranded DNA
double or single stranded DNA or RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is a wild type strain

A

isolated from nature, also can refer to just 1 gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is a mutant

A

A cell or virus derived from wild type that carries a nucleotide sequence (genotype) change. Genotype designated by three lowercase letters followed by capital, italicized (e.g., hisC). Mutations designated
his C1, his C2, etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

whats the difference between selectable and non-selectable mutants

A

depends on whether the mutation gives the organism a survival advantage under specific conditions.
- selectable = advantage(mutation that allows it to survive or grow under selective conditions where normal (wild-type) cells cannot.)
- non selectable = no advantage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the detection of an auxotroph mutant

A

inability to grow on medium lacking the nutrient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the detection of an antibiotic resistant mutant

A

Growth on medium containing a normally inhibitory concentration of the antibiotic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the detection of a Sugar fermentation mutant

A

Lack of color change on agar containing sugar and a p H indicator.
Differential Media

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the detection of a virus resistant mutant

A

Growth in presence of large amounts of virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

spontaneous mutations occur without _________

A

external intervention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the most common reason for a spontaneous mutation

A

occasional errors by DNA polymerase during replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

induced mutations are caused_______ or ______

A

environmentally or deliberately

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

exposure to natural radiation or chemicals that chemically modify DNA is an example of what type of mutation

A

induced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are point mutations

A
  • Change only one base pair
  • Occurs via single base-pair substitution
  • Phenotypic change depends on exact location of mutation within DNA
    sequence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is a silent mutation

A

not affect sequence of encoded polypeptide or phenotype (e.g., UAC to UAU)
- almost always third base codon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is a missense mutation

A

changes sequence of amino acids in polypeptide
-If at a critical location, e.g., active site,
could alter activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

TF all missense mutations lead to dysfunction

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is a nonsense mutation

A

changes a normal codon into a stop codon
- results in incomplete protein that lacks normal activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

if most microorganisms have a rate of error of 10^-6 to 10^-8, whats the rate of error of eukaryotes, DNA viruses and RNA viruses

A

eukaryotes :10x fewer errors
DNA viruses: 100-1000x higher errors
RNA viruses: even higher error, no proof reading

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is a reversion (back mutation)

A

restores the original phenotype after a
mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

TF point mutations can be reversed

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are 2 types of reversions

A
  1. Same-site reversion – second mutation at the same DNA site restores
    original sequence.
  2. Second-site reversion (suppressor) – new mutation elsewhere restores
    normal function.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are mutagens

A

chemical, physical, or biological agents that increase mutation rates,
induce mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what are 4 types of chemical mutagenesis
- nucleoside analogues (AT<-->CG) - nitrous oxide (CG --> AT) - intercalating agents (deletion or inertion) - alkylating agents (point mutations and deletions)
26
how can mutations be corrected (DNA repair)
- proofreading by DNA polymerase - mismatch (recognize, excise, replace) - UV induced thymidine dimers (nucleotide excision repair, photoreactivation/light repair
27
what are homologous genes
Genes that all descended from single ancestral gene. Tend to have similar nucleotide sequences
28
what are orthologs
Homologous genes sharing same function
29
what are paralogs
Single ancestral gene diverges to many different functions in many different organisms
30
what are gene families
groups of gene homologs
31
how is radiation a mutagen
○ Ionizing § Leads to formation of single or dbl stranded breaks ○ non-ionizing § UV light can lead to thymine dimers, can stall replication and transcription
32
whats most common: deletion, insertion, duplication
deletion
33
what is evolutionary selection defined by
fitness - ability of an organism to produce progeny and contribute to genetic makeup of future generations
34
deleterious mutations ______ fitness and are ______ overtime
decrease removed
35
Beneficial mutations ______ fitness and are favored by ________
increase natural selection
36
TF Over time, drift can lead to loss of genetic variation and fixation of alleles
T
37
what is genetic drift
Genetic drift is a change in allele frequencies in a population due to random chance, not natural selection.
38
what is the founder effect
When a small group of individuals breaks away from a larger population and creates its own population in a separate location, rare alleles could be overrepresented in this newly "founded" population
39
what is the bottleneck effect
when a random event, such as a natural disaster, unselectively reduces the size of a population
40
how do we create diversity without sex
Horizontal gene transfer
41
how does HGT work
- Donor DNA integrates into recipient by homologous recombination - Occurs via transformation, transduction, and conjugation
42
what is gene conversion in HGT
donor sequence replaces recipient copy. Persists if beneficial; deleted if not
43
what is horizontal gene transfer vs vertical gene transfer
- Horizontal gene transfer is the movement of genetic material between organisms that are not parent and offspring. - Vertical gene transfer is the transmission of genetic material from parent to offspring during reproduction.
44
what is transformation
Genetic transfer process by which free (naked) DNA is incorporated into a recipient cell and brings about genetic change
45
how does gram negative bacteria transformation work
proteins within pilus recognize and bind extracellular DNA, pilus retraction pulls DNA into cell
46
what is a "competent" cell
a cell that can take up DNA and be transformed; genetically determined .In some bacteria, competence linked to pili
47
what is conjugation
Horizontal gene transfer that requires cell-to-cell contact
48
how does conjugation work
pilus of donor cell attaches to recipient cell - DNA transfered - donor synthesizes strand to restore plasmid
49
when do Hfr (high freq recombination) cells form
when there's an F plasmid integrated into the bacterial chromosome.
50
what are the steps to how Hfr cells transfer chromosomal genes to F- bacteria
- DNA transfer begins at the origin of transfer - Chromosomal genes adjacent to the F factor are transferred first. - Transfer occurs through a conjugation pilus - Conjugation is often interrupted before the entire chromosome (and full F factor) is transferred. - as a result the recipient usually remains F-
51
Different Hfr strains have F plasmids integrated at different sites and orientations, producing varied gene transfer sequences.
T
52
Imprecise excision of the F plasmid from the chromosome of an Hfr cell may lead to the production of an______
F’ plasmid
53
whats the difference between generalized transduction and specialized transduction
- lytic cycle bacteriophage vs lysogenic cycle temperate phage - any bacterial gene packaged vs specific genes next to phage insertion site - DNA in new bacteria vs part of genome + transferred to next host - packaging error vs excision error
54
what is more efficient specialized or general transduction
specialized way more
55
what is phage conversion in transduction
- A virus (phage) inserts its DNA into a bacterium. This permanently changes the bacterium's traits. - The result: The bacterium becomes immune to attacks from that same virus. - this immunity helps for survival
56
what does the Mobilome consist of
plasmids, prophages, insertion sequences and transposons
57
what happens in the mobilome
The DNA pieces (plasmids, prophages etc) can cut themselves out and move to a new spot, sometimes bringing extra genes (like antibiotic resistance) with them.
58
TF the Mobilome drives genome evolution
T
59
what are the 5 major phyla
proteobacteria firmicutes actinobacteria tenericutes Bacteroidetes
60
what are the key traits of the 5 phyla
proteobacteria - metabolically diverse firmicutes - endospores, fermentation actinobacteria - antibiotic producers tenericutes - parasites Bacteroidetes - anaerobic degraders of complex molecs
61
proteobacteria are ______ of all known species, the ______phylum, Occupy every _____, are Gram ____,
1/3 largest niche negative
62
TF proteobacteria are deficient in LPS
F, Rich in LPS
63
what the difference between alpha, beta, gamma, and epsilon proteobacteria
alpha - N fixers, intracellular pathogen beta - commensals and opportunistic pathogens gamma - diverse, many human and animal pathogens epsilon - Microaerophile pathogens
64
tell me about rickettsiales
- alphaproteobacteria - gram -ve - transmitted by ticks and fleas - need host cells - intracellular
65
Betaproteobacteria are the _____ largest class of proteobacteria, they need _________, (eutrophs)
third Organic nutrients
66
tell me about neisseriales
- Commonly isolated from animals from moist areas/oral cavity - Some pathogenic - Always cocci
67
gamma proteobacteria is the ______ and most diverse class, Many well known ______pathogens, Respiratory or fementive _________.
largest human metabolisms
68
tell me about the gammaproteobacteria enterobacteriaceae
- facultative aerobic, gram -ve, non sporulating - Oxidase (negative) and catalase (positive) tests can be used to discriminate enteric from many other bacteria - simple nutrient requirements
69
what tests can be done to discriminate enteric bacteria from others
Oxidase (negative) and catalase (positive) tests
70
Oxidase test assays for ________ catalase test assays for catalase which breaks down _______
cytochrome C hydrogen peroxide
71
what do mixed acid fermenters make
They produce large amounts of stable acids from glucose, so the pH drops significantly, also ferment sugars
72
what does Escherichia do
synthesize vitamin K
73
what does proteus cause
UTI
74
what do mixed-acid fermenters require
absence of butane diol
75
how do butane diol fermenters act vs mixed acid fermentors
Both ferment glucose. They just handle pyruvate differently. Mixed acid fermenters → produce lots of stable acids Butanediol fermenters → convert acids into neutral products like butane diol
76
the gammaproteobacteria: Pseudomonades can cause plant and animal _____ and are gram _____
diseases negative
77
betaproteobacteria are the ___ largest class, and are ________.
3rd eutrophs - needs nutrietns
78
what are the 3 phylum of gram positie bacteria
Firmicutes, Tenericutes, and Actinobacteria
79
Actinobacteria has a ______ cell wall with ______ acid, and are ________ producers
Thick mycolic Antibiotic producers
80
Tenericutes have _____ cell wall, _____ GC content and are the smallest ______________
No Low self-replicators
81
Firmicutes have a _____ CW, ______ GC content and are ________ formers
Thick Low Endospore
82
what is homofermentive vs heterofermentive metabolism in the Firmicute Lactobacillales
*Homofermentative → lactic acid only *Heterofermentative → lactic acid + CO₂ + ethanol
83
what are the firmicutes
lactobacillales streptococcus staphylococcus Bacillus Clostridium
84
mycoplasmas are ________, they lack a____ and are not inhibited by _______, contains ______ in the membrane and usually live in osmotically _______ environments
tenericutes CW antibiotics sterols protected
Microbiology (BMSC 210)
flashcards
Decks in class (10)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions