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Microbiology > Chapter 8 - Bacterial Genetics > Flashcards

Chapter 8 - Bacterial Genetics Flashcards

(64 cards)

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1
Q

How do bacteria adapt to changing environments?

A

Mutations and Horizontal gene transfer

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2
Q

Are bacteria haploid or diploid?

A

haploid

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3
Q

What are the three mechanisms of gene transfer?

A

Transformation, Transduction, and Conjugation

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4
Q

What is transformation?

A

naked DNA uptake by bacteria

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5
Q

What is transduction?

A

bacterial DNA transfer by bacteriophages

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6
Q

What is conjugation?

A

direct DNA transfer between bacterial cells

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7
Q

Which mechanism is sensitive to deoxyribonuclease?

A

transformation

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8
Q

Which mechanism requires cell-to-cell contact?

A

conjugation

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9
Q

Can DNA without an origin of replication replicate?

A

NO

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10
Q

What are replicons?

A

plasmids, chromosomes

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11
Q

How are some DNA fragments added to chromosomes?

A

homologous recombination

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12
Q

What is generalized transduction?

A

any genes of donor cell are transferred

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13
Q

What is specialized transduction?

A

specific genes are transferred

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14
Q

What cells are pathogenic in pneumococci?

A

Only encapsulated cells

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15
Q

What is special about the host cell in transformation?

A

The recipient cell must be competent

*some accept only from closely related bacteria (DNA sequence)

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16
Q

What kind of plasmids direct their own transfer in conjugation?

A

conjugative plasmids

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17
Q

What are the two types of conjugation?

A

Plasmid transfer and Plasmid + chromosome transfer

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18
Q

What is the process of plasmid transfer?

  • use the F plasmid of E. coli
    • F+ cells have, F- do not
A

1) pili bring cells into contact
2) enzyme cuts plasmid
3) single strand transferred
4) complementary strands synthesized
5) both cells are now F+

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19
Q

What is the process of Chromosomal DNA transfer?

A

1) Hfr cells involved (high frequency recombination cells)
2) F plasmid is integrated into chromosome via homologous recombination
3) process is reversible

a) Hfr cell produces F pilus
b) transfer begins with genes on one side of origin of transfer of plasmid (in chromosome)
c) part of chromosome transferred to recipient cell
d) chromosome usually breaks before full transfer (~100 minutes)
e) recipient cell remains F- since incomplete F plasmid transferred

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20
Q

What is the Start codon and amino acid?

A

AUG and Methionine (Met)

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21
Q

What are the Stop codons?

A

UAA, UAG, UGA

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22
Q

What are the two major types of mutations?

A

Base substitution mutations and Addition/Deletion (frameshift)

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23
Q

What is the basis of base substitution mutations?

A

incorrect nucleotide/s incorporated during DNA synthesis

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24
Q

What is a point mutation?

A

change of a single base pair

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25
What are the three possible outcomes of base substitution mutations?
Silent mutation, missense mutation, and nonsense mutation
26
What is a silent mutation?
wild-type amino acid is still made
27
What is a missense mutation?
Different amino acid or effect on protein depends upon role played by changed amino acid
28
What is a nonsense mutation?
Specifies stop codon or nonsense codon and yields shorter protein
29
What is a mutation called that inactivates a gene?
A null or knockout mutation
30
Why are base substitutions more common in aerobic environments?
Reactive oxygen species (ROS) produced from O2 and can oxidize nucleobase guanine which DNA polymerase often mispairs with adenine
31
What effects the outcome of Addition/deletion mutations?
the number of nucleotides involved
32
What yields a frameshift mutation?
one or two nucleotide changes
33
What does a frameshift mutation do?
results in a different set of codons translated and often results in a nonfunctional protein
34
What does a three nucleotide change do?
adds or removes one amino acid and the impact depends on where the addition/deletion takes place
35
What are transposons?
- "Jumping genes" - can move from one location to another through a process called transposition - usually inactivates the gene to which it inserts
36
Can transposons replicate independently?
NO
37
Who discovered transposons and how did they study them?
Barbara McClintock and she observed color variation in corn kernels
38
What are Spontaneous Mutations and how often do they occur?
Mutations that occur randomly at infrequent but characteristic rates Rate = 10^-6 for a given gene -mutations are passed to progeny
39
What is it called when a mutation changes back to its original state?
Reversion
40
What are induced mutations?
Mutations that result from outside influence
41
What is the agent that induces mutation?
Mutagen
42
What do mutagens do to the mutation rate?
increase it | rate = 10^-3
43
What are the two general types of mutagens?
Chemical and radiation
44
What does nitrous acid do?
Causes a nucleotide substitution by converting cytosine to uracil -base pairs with adenine instead of guanine
45
What do alkylating agents do?
Cause nucleotide substitutions by adding alkyl groups (CH3 and others) to nucleobases - nitrosoguanidine adds methyl group to guanine - -Changes GC to GT
46
What do base analogs (5-bromouracil) do?
Cause nucleotide substitutions by being used in place of normal nucleobases in DNA --resembles thymine and often pairs with cytosine
47
What do intercalating agents (ethidium bromide) do?
Add or subtract nucleotides by inserting between base pairs - -push nucleotides apart, producing space and causes errors during replication - --likely carcinogen
48
What do transposons do?
insertionally inactivate DNA by randomly inserting themselves
49
What does UV light do?
Causes errors during repair process by creating intrastranded thymine dimers to form - -distorts molecules at the covalent bonding - --cells die if not repaired
50
What do x-rays do?
Cause deletions by causing single and double-stranded breaks in DNA - -double stranded breaks often cause lethal deletions - -alter nucleobases
51
What is non ionizing radiation?
UV
52
What is ionizing radiation?
X-ray and Gamma ray
53
What is the "Mobile Gene Pool"
plasmids found in most bacteria, archaea - some Eucarya - usually double stranded DNA with origin of replication - generally nonessential; cells can be cured - Few to thousands of genes - most have a narrow host range (single species) - some broad host range (include G- and G+) - one or a few or many per cell
54
Which organisms have plasmid coded traits for antibiotic resistance?
E. coli, Salmonella sp, Neisseria sp, Staphylococcus sp, and Shigella sp
55
Which organisms have plasmid coded traits for pilus synthesis?
E. coli, Pseudomonas sp
56
Which organisms have plasmid coded traits for tumor formation in plants?
Agrobacterium sp
57
Which organisms have plasmid coded traits for nitrogen fixation?
Rhizobium sp
58
Which organisms have plasmid coded traits for Oil degradation?
Pseudomonas sp
59
Which organisms have plasmid coded traits for Gas vacuole production?
Halobacterium sp
60
Which organisms have plasmid coded traits for Insect toxin synthesis?
Bacillus thuringiensis
61
Which organisms have plasmid coded traits for plant hormone synthesis?
Pseudomonas sp
62
Which organisms have plasmid coded traits for antibiotic synthesis?
Streptomyces sp
63
Which organisms have plasmid coded traits for Increased virulence?
Yersinia sp
64
Which organisms have plasmid coded traits for toxin production?
Bacillus anthracis

Microbiology (9 decks)

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