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Microbiology Exam 1 > Microbial Genetics > Flashcards

Microbial Genetics Flashcards

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1
Q

What are the two types of bacterial genetic material?

A

1) bacterial chromosome

2) plasmid

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2
Q

What’s the difference between bacterial chromosome and plasmid?

A

1) chromosome is a single, large circular DNA molecule. it contains all genes for survival
2) plasmid is a small, circular DNA moledule. copy number varies

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3
Q

Sometimes plasmid may integrate into bacterial chromosome, what is this called?

A

episomes

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4
Q

Human genomes contain 23 chromosomes, what about bacterial genomes?

A

one

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5
Q

Human cells are diploid, what about bacteria?

A

haploid (only 1 copy)

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6
Q

Are exons and introns present in bacteria?

A

no

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7
Q

Are histones present in bacteria?

A

no

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8
Q

How do transcription and translation differ between humans and bacteria?

A

In bacteria, transcription and translation are coupled because they lack nucleus.
In humans, transcription and translation are two separate processes

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9
Q

Genes on bacterial chromosome are polycistronic, what does that mean?

A

one promoter can drive transcription of multiple genes whereas human genes are monocistronic

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10
Q

Repression is ____ type of gene regulation while activation is ____ type of gene regulation

A

repression –> negative

activation –> positive

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11
Q

Describe repression

A

a repressor is required to stop gene transcription, meaning gene transcription is always on otherwise

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12
Q

Describe activation

A

an activator is required to start transcription because RNA polymerase alone does not have enough affinity for promoter region

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13
Q

What are the two types of gene transfer in bacteria?

A

1) vertical

2) horizontal

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14
Q

Which type of gene transfer is this, genes are passed via replication to progeny?

A

vertical

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15
Q

What are the three types of horizontal gene transfer?

A

1) transformation
2) conjugation
3) transduction

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16
Q

True or False. No new DNA is acquired during cell division

A

True

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17
Q

Bacterial multiplication is a sexual or asexual process?

A

asexual

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18
Q

Is evolution of new traits like resistance to antibiotics a slow or fast process in bacteria?

A

SLOWWWW

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19
Q

How do bacteria become antibiotic resistance and produce new virulence factors so fast?

A

horizontal gene transfer

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20
Q

True or False. Horizontal gene transfer can occur only between same species of bacteria

A

False. it can occur between species within genus as well

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21
Q

What is homologous recombination?

A

exchange of DNA between two DNA molecules based in homology

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22
Q

Describe the process of homologous recombination

A

1) exchange of DNA between 2 pieces of DNA with homologous sequence
2) recombination is aided by a recomination protein such as RecA
3) linear DNA is degraded
Note that DNA that was incoporated is now passed down to daughter cells and becomes a permanent part of the genome

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23
Q

Which type of horizontal gene transfer is this involves uptake of free DNA from the environment?

A

transformation

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24
Q

Which type of horizontal gene transfer involves DNA transfer directly from one bacterial cell to another through cell contact?

A

conjugation

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25
Q

Which type of horizontal gene transfer involves the transfer of bacterial DNA via bacteriophage?

A

transduction

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26
Q

Which type of horizontal gene transfer allow bacteria to gain new traits quickly?

A

transformation

27
Q

Which type of horizontal gene transfer allow one bacterium to acquire new DNA from another viable bacterium?

A

conjugation

28
Q

Briefly describe the process of transformation

A

1) a bacterium (donor cell) lyses and releases DNA fragments to environment
2) DNA enters recipient cell and is integrated into its DNA via homologous recombination

29
Q

True or False. DNA transfer in conjugation is bi-directional

A

False. it is uni-directional

30
Q

What is F factor?

A

Fertility factor that carrier genes, tra operon, that encode components for sex pillus

31
Q

Briefly describe the transfer of DNA from F+ to F-

A

F+ extends out a sex pilus to recipient (F-). A single strand of plasmid is transferred.

32
Q

Briefly describe the transfer of DNA between Hfr and F-

A

HFR has the F factor integrated into its chromosome, Part of the genome will get transferred but before it finishes the unstable sex pilus will disappear. Homologous recombination will occur and the F- received new bacterial genes

33
Q

In conjugation between F+ and F-, are bacterial genes transferred?

A

No, only a single strand is transferred (F factor)

34
Q

The transfer of bacterial DNA via a bacteriophage

A

transduction

35
Q

What are the two different life cycles of a bacteriophage?

A

1) lytic/ virulent phage

2) temperate phage

36
Q

What occurs in lytic phage?

A

lytic replication upon entry

37
Q

What occurs in temperate phage?

A

lysogeny (integration into the chromosome) can excise and undertake lytic replication

38
Q

Where does a lytic phage incorporate bacterial chromosomal DNA into?

A

its phage head

39
Q

When the phage infects another bacteria, the DNA can be incorporated into its chromosome via which process?

A

homologous recombination

40
Q

Lysogenic phage incorporates into the chromosome as a what?

A

prophage

41
Q

What leads to conversion of lysogenic phage into lytic lifecycle

A

an event such as UV damage (basically virus sense trouble to host)

42
Q

What occurs after excision from the genome?

A

a small portion of the chromosome, directly adjacent to where the phage was integrated is packaged into a phage head

43
Q

Which of the three horizontal gene transfers utilizes free DNA?

A

transformation

44
Q

Which of the three horizontal gene transfers require cell-to-cell contact?

A

conjugation

45
Q

Which of the three horizontal gene transfers require homologous recombination?

A

transformation
transduction
conjugation ( only in Hfr with F-)

46
Q

What are the three general categories of antibiotic resistance?

A

1) intrinsic
2) chromosome-mediated
3) plasmid-mediated

47
Q

Which of the three types of antibiotic resistance is not transferable (horizontally) between bacteria?

A

intrinsic

48
Q

Which of the three types of antibiotic resistance is not increasing among bacterial populations?

A

intrinsic

49
Q

What’s an example of intrinsic antibiotic resistance?

A

lack of cell wall (mycoplasma)

50
Q

Which of the three types of antibiotic resistance allow chromosomal genes encoding antibiotic resistance?

A

chromosome-mediated

51
Q

How does chromosomal-mediated antibiotic resistance arise?

A

1) random mutation during replication

2) acquisition of DNA through horizontal gene transfer and incorportation into the genome via homologous recombination

52
Q

What are examples of chromosomal-mediated antibiotic resistance?

A

1) ribosomal proteins
2) penicillin-binding proteins
3) DNA gyrase

53
Q

Where are plasmid-mediated antibiotic resistance genome located?

A

plasmid

54
Q

Commonly plasmids carry genes that encode proteins for what?

A

1) degradation of antibiotic
2) modification of antibiotic
3) efflux pump to pump antibiotic out of cell

55
Q

What is R-factor?

A

resistance factor, a conjugative plasmid

56
Q

What are the two components to R-factor?

A

1) resistance transfer factor

2) resistance determinant

57
Q

What is resistance transfer factor?

A

similar to F factor that it encodes all proteins needed for conjugation

58
Q

What is resistance determinant?

A

gene(s) for drug resistance

59
Q

What are transposons?

A

mobile DNA elements that can transfer themselves (or a copy) from one molecule to another

60
Q

What does a simple transposon contain?

A

1) indirect repeat sequences on each end
2) single gene for transposae, TnpA, enzyme required for “jumping”
3) contain a single or multiple antibiotic resistance gene(s)

61
Q

What are some ways transposons can pass down multi-drug resistance?

A

1) between two chromosomes
2) between two plasmids
3) between on of each

62
Q

What are integrons?

A

diverse group of genetic elements that encode a site-specific recombination system that can capture gene cassettes and express them in a coordinated manner under the control of the integron promoter

63
Q

What are pathogenicity islands?

A

region of bacterial chromosome acquired through horizontal gene transfer, often carry coordinately regulated virulence genes surrounded by insertion sequences (like a large tranposon)

Microbiology Exam 1 (10 decks)

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