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Flashcards in bacterial genetics Deck (68)
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1
Q

genome

A

genetic info in a cell, DNA

2
Q

how may chromosomes do most bacteria have?

A

one

3
Q

what is a gene?

A

segments of DNA that code for functional products

4
Q

what are genomics?

A

sequence and molecular characterization of genome

5
Q

what makes up a nucleotide?

A
  • sugar
  • base
  • phosphate
6
Q

what makes up a nucleoside?

A

sugar and base

7
Q

what nitrogen bases are pyrimidine bases?

A

CTU

-cytosine, thymine, uracil

8
Q

what nitrogen bases are purine bases?

A

AG

-adenine, guanine

9
Q

what type of bonds hold nucleic acid pairs together?

A

hydrogen bonds

10
Q

how many bonds hold G and C together?

A

3

11
Q

how many bonds hold A and T (U) together?

A

2

12
Q

which is more stable, GC or AT bonds?

A

GC

13
Q

what is the primary structure of nucleic acids?

A

the sequence of the nucleotides in DNA or RNA

14
Q

what are the secondary structures of nucleic acids?

A

intrastrand base pairing, observed in rRNA or tRNA

15
Q

is RNA single or double stranded?

A

singe stranded

16
Q

what are the three types of RNA?

A

mRNA, tRNA, rRNA

17
Q

what is mRNA?

A

single-stranded and complementary to DNA (transcription)

18
Q

what is tRNA?

A

translate genetic info

19
Q

what is rRNA?

A

components of ribosome

20
Q

What is denaturation (melting) of DNA?

A

separation of strands with breakage of H2 bonds

21
Q

what is annealing of DNA?

A

coming together of two strands with formation of H2 bonds

22
Q

what is hybridization of DNA?

A

formation of ds by complementary base pairings of two ss

23
Q

what is DNA supercoiling?

A
  • twisting of ds DNA
  • allows packaging of strands of DNA in a cell
  • neg or pos direction
  • NEG is more common
24
Q

what are topoisomerases?

A

-cause DNA to relax or supercoil

25
Q

what does the topoisomerase, DNA gyrase do?

A

introduces negative strands

26
Q

what does topoisomerase I do?

A

removes supercoiling

27
Q

what does topoisomerase IV do?

A

unlinks the two circular molecules of DNA during replication

28
Q

what are plasmids?

A

small molecules of DNA that replicate independent of the chromosome

29
Q

what is the copy number of plasmids?

A

number of plasmids per cell

30
Q

what is curing of plasmids?

A

loss of elimination of plasmids

31
Q

what are the functions of plasmids?

A

carry gene codes for:

  • antibiotic resistance
  • virulence factors
  • chemical resistance
  • sex pili
  • enzymes for environmental contamination
32
Q

what are transposons?

A

transposable genetic elements or jumping genes

33
Q

what do transposons do?

A

they are segments of DNA that can move from one site to another site on the same chromosome
-contain info for transposition (removal and instertion)

34
Q

what cells have transposons?

A

prokaryotic and eukaryotic cells

-plays a role in genetic variation

35
Q

what are the two types of transposons?

A
  • insertion sequences: IS1, IS2, etc, contain a gene that codes for transposase
  • transposons: Tn1, Tn2, etc, these are larger
36
Q

T/F: transposons with antibiotic resistance can move resistance to other bacteria?

A

true

37
Q

what are bacteriophages?

A

viruses that infect bacteria

38
Q

what are the two types of baceriophages?

A

-lytic or lysogenic(temperate)

39
Q

what is bactriophage immunity?

A

presence of prophage prevents infection by the same phage

40
Q

what is phage conversion?

A

presence of prophage confers new properties

41
Q

what is phage therapy?

A

the therapeutic use of lytic bacteriophages to treat bacterial infections

42
Q

lytic phages are similar to what?

A

antibiotics

43
Q

what is a mutation?

A

change in nucleotide base sequence that is inherited

44
Q

what is genetic recomination?

A

genes from two different genomes are brought together

45
Q

which brings about a larger change, mutation or recombination?

A

recombination

46
Q

define horizontal gene transfer

A

from a donor cell to a recipient cell

47
Q

define vertical gene transfer

A

mother to daughter cell

48
Q

define mutant

A

an organism that carries mutation

49
Q

define wild type strain

A

parental strain that existed in nature

50
Q

define genotype desgnation

A

italicized gene encodes for a protein (?)

51
Q

define phenotype designation

A

His+ or His-

52
Q

what can cause spontaneous mutation?

A
  • exposure to natural factors (oxygen radicals, etc)

- errors in base pairing during replication

53
Q

what is point mutation?

A

change in one base pair - the phenotypic change depends on where the mutation occurs

54
Q

what is a silent point mutation?

A

no phenotypic change

55
Q

what is nonsense point mutation?

A

termination of protein synthesis

56
Q

what is missense point mutation?

A

coding a different amino acid

57
Q

what is a frameshift mutation?

A

insertion or deletion of a base pair results in reading frame shift

58
Q

what is transposon mutagenesis?

A

mutation due to insertion of transposon (insertion sequence)

59
Q

what is site directed mutagenesis?

A

mutation at a specific site or gee

60
Q

what is genetic recombination?

A

physical exchange of genes between genetic elements

61
Q

what are the three mechanisms of genetic recombination?

A
  • transformation
  • transduction
  • conjugation
62
Q

define transformation as a mechanism of genetic recombination

A

incorporation of free DNA into a recipient cell

63
Q

a bacterium capable of being transformed is called what?

A

competent

64
Q

define transduction as a mechanism of genetic recombination

A

DNA transfer is mediated by bacteriophage

65
Q

what are the two methods of transduction

A
  • generalized transduction

- specialized transduction

66
Q

what is generalized transduction?

A

DNA from any portion of the host genome is transferred

67
Q

what is specialized transduction

A

DNA from specific region of the host genome is transferred

68
Q

what is conjugation as a mechanism of genetic recombination

A

DNA transfer is mediated by a cell to cell contact

-mediated by a conjugative plasmid from the donor cell