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microbio 3810 > 4. microbial genetics > Flashcards

4. microbial genetics Flashcards

1
Q

the basic unit of heredity; a segment of DNA that encodes for a gene product (polypeptide, protein or RNA)

A

gene

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2
Q

is the entire set of DNA instructions found in a cell. contains all the information needed for an individual to develop and function. consists the coding regions of DNA and non coding regions

A

genome

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3
Q

this is the genetic material found in the cell passed through generations

A

genotype

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4
Q

what are some examples of genotypes found in the cell?

A

plasmid, chromosomes

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5
Q

this is the observable characteristic or traits of an organism

A

phenotype

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6
Q

what are some examples of phenotypes found in the cell?

A

flagellum, cell wall, pili, proteins, capsule

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7
Q

T/F: transcription and translation occur in the same area in a prokaryotic cell

A

true - both occur in cytoplasm because prokaryotic cell doesn’t have a nucleus

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8
Q

T/F: transcription and translation occur in the same area in a eukaryotic cell

A

false
transcription - nucleus
translation - cytoplasm

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9
Q

what is the product and reactant of transcription?

A

DNA -> mRNA
the mRNA (referred to as ssRNA) is transcribed as the RNA complement to the coding DNA strand

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10
Q

what enzyme catalyzes transcription?

A

RNA polymerase

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11
Q

_____ is performed by ribosomes in the cytoplasm of the cell

A

translation

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12
Q

____- participates in translation (polypeptide synthesis) by transferring the amino acids from the cytoplasm to the ribosomes and binding them to the peptide chain according to the mRNA codons

A

tRNA (transfer RNA)

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13
Q

these two types of RNA tend to be stable and together account for more Ethan 95% of the total RNA in a bacterial cell

A

rRNA and tRNA

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14
Q

____ eukaryotic cells contain two homologous of each chromosome

A

diploid

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15
Q

the gene which does not achieve phenotypic expression in the precedes of its homologue is ______

A

recessive

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16
Q

the gene that overrides the effect of its homologue is ____

A

dominant

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17
Q

region that resides within a gene but does not remain in the final mature mRNA molecule following transcription of that gene and does not code for amino acids that make up the protein encoded by that gene; found only in eukaryotes

A

introns

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18
Q

som eukaryotes, such as yeast, contain _______ - additional circular genetic materials that independently replicate

A

plasmids or episomes

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19
Q

most _____ genomes consist of a single circular DNA molecule chromosome

A

prokaryotic

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20
Q

a few bacteria have two chromosomes. what are some examples?

A
  • brucella melitensis
  • burkholderia pseudomallei
  • vibrio cholerae
21
Q

some bacteria have linear chromosomes, not circular. what are some examples?

A
  • acintomycetes
  • mycobacteria
22
Q

bacterial genes are _____ (haploid/diploid)

A

haploid

23
Q

many bacteria contain additional genes on _______. these are not important for the life of bacteria, they just give extra characteristics to the bacteria

A

plasmids

24
Q

in contrast to eukaryotic genomes, 98% of bacterial genomes are __________ (coding/noncoding) sequences

A

coding

25
Q

T/F: genes essential for bacterial growth and reproduction are carried on the plasmid

A

false - carried on the bacterial chromosome found in the core part of the chromosome

26
Q

these structures of the prokaryotic genome are double-stranded DNA molecules that can exist and replicate independently. some of these can integrate into the hosts chromosome. they are NOT required for bacterial growth or reproduction.

A

plasmids

27
Q

plasmids carry genes that give their host a selective advantage. list these four advantages

A
  1. render bacteria drug-resistant
  2. give them new metabolic abilities
  3. make them pathogenic
  4. provide them with other properties
28
Q

plasmids mediate their transfer from one organism to another through _____ and ______ formation

A

conjugation and sex pili

29
Q

plasmids are responsible for properties that can spread throughout a bacterial population such as _________

A

drug resistance - plasmids can move from antibiotic resistant bacteria to non-antibiotic resistant bacteria

30
Q

these are distinct genetic elements on the chromosomes of a large number of bacterial pathogens; they encode various virulence factors and are normally absent from non-pathogenic strains of the same closely related species

A

pathogenicity islands (PAIs)

31
Q

what are some characteristic of PAI’s?

A
  • they have a different guanine + cytosine content from the rest of the genome of that bacteria
  • they are closely linked on the chromosome to tRNA genes
  • they are flanked by different repeats: allows the PAIs to be copied and inserted at a different locating of the genome
  • they contain diverse genes important for pathogenesis, including antibiotic resistance, adhesions, invasions, exotoxins, and genes involved in genetic mobilization
32
Q

these are a class of genetic elements that can move or “jump” to different locations within a genome; they are always integrated into the genome (chromosomes or plasmids) and can not replicate by themselves. They eventually become inactive and no longer move overtime

A

transposons

33
Q

these are the simplest transposable elements which are found in almost all bacteria, viruses and some eukaryotes.; they create insertion mutations

A

insertion sequences elements (IS)

34
Q

these are elements that could have antibiotic resistance or toxins genes

A

composite transposons

35
Q

DNA replication in prokaryotes:
the replication off bacterial DNA begins at one point (oriC) and terminates in a region called ter. Does it move in one direction or both directions?

A

both directions - bidirectional replication

36
Q

during DNA replication in prokaryotes, the two old strands of DNA are separated and used as templates to synthesize new strands. this is called:

A

semiconservative replication

37
Q

during semiconservative replication, the structure where the two strands are separated is referred to as the ____________

A

replication fork

38
Q

this is a large protein complex that carries out DNA replication in prokaryotes and has several enzymatic activities (DNA polymerases I, II and III)

A

replisome

39
Q

these are enzymes that alter the supercoiling of dsDNA, by cutting the DNA to relax the oil and extend the DNA molecule

A

topoisomerases (DNA gyrase)

40
Q

____________ are the targets of antibiotics e.g. quinolones - therefore DNA replication will not occur

A

topoisimerases

41
Q

what are the two mechanisms of gene transfer?

A
  1. vertical gene transfer
  2. horizontal gene transfer
42
Q

this is the vertical inheritance of parental genes to the progeny cells (offspring)

A

vertical gene transfer

43
Q

this is where DNA can be transferred from one organism to another, for e.g. to another bacteria; the DNA can be stably incorporated into the recipient, permanently changing its genetic composition

A

horizontal gene transfer

44
Q

what are the three mechanisms that mediate horizontal gene transfer?

A
  1. conjugation
  2. transduction
  3. transformation
45
Q

mechanism that mediates HGT:
this mechanism requires donor cell-to-recipient cell contact to transfer only one strand of DNA. the recipient completes the structure of dsDNA by synthesizing the strand that complements the strand acquired from the donor.

A

conjugation

46
Q

_____ are most frequently transferred by conjugation

A

plasmids

47
Q

in conjugation, these are responsible for the formation of sex pilus and the extracellular multimeric proteins that attach donor cells to recipient cells; some of these can mobilize other plasmids of portions of the chromosome for transfer

A

fertility factors or self-transmissible plasmids (have tra genes)

48
Q

mechanism that mediates HGT:
this is a phage (virus) mediated genetic recombination in bacteria. the phages infect bacterial cells and propagate inside them. when they leave the cell to infect other cells, they take some bacterial genes with them

A

transduction

49
Q

mechanism that mediates HGT:
this is the direct uptake of extracellular “naked” DNA by the recipient cell; this process can be natural of forced.

A

transformation

microbio 3810 (16 decks)

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