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Microbiology > Lab Quiz #4 > Flashcards

Lab Quiz #4 Flashcards

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Biology 101 flashcards
1
Q

What do T helper cells produce after being activated by an MHC/peptide complex?

A

Cytokines

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2
Q

T cell activation assay: what type of T helper hybridoma used? How created?

A

KZH
Fusing normal T helper cells from mice immunized with antigen lysozyme with T lymphoma cell transfected with reporter construct

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3
Q

KZH hybridoma T cells have what gene that encodes what enzyme under transcriptional control of what transcriptional regulator?

A

lacZ gene
Encodes beta galactosidase
Cytokine IL-2 gene promoter

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4
Q

What happens when KZH cells are activated by antigenic peptide/MHC complex?

A

Transcription of IL-2 promoter and lacZ gene, producing IL-2 and beta galactosidase

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5
Q

How can beta-galactosidase be detected in T cell assay?

A

Lysing cells with detergent Triton X-100 and adding chromogenic substrate chlorophenol red galactoside (CPRG)
CPRG turns from yellow to red when hydrolyzed by beta galactosidase

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6
Q

What was the antigen presenting cell used in the T cell assay and what was the antigen?

A

APC: LK35.2 (mouse B cell hybridoma)
Antigen: lysozyme

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7
Q

Culture of KZH and LK35.2 cells was done using what type of incubator? What is flushed through incubator? What does this do for cells?

A

CO2 incubator
5% CO2 is flushed through incubator
CO2 establishes equilibrium with bicarbonate in growth medium, forming pH buffer of 7.4 to support optimal growth of cells

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8
Q

What type of medium was used for T cell assay? What did it contain?

A

RPMI-1640

Metabolic building blocks, buffer, antibiotics

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9
Q

Why was centrifugation step necessary in T cell assay?

A

Culture medium contained phenol red dye, which would interfere with color produced in assay
Pelleted cells stayed in plates while supernatant (medium) was removed

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10
Q

Antibiotics have what microbial origin? How do they affect other microbes?

A

Metabolic products of microbes

Toxic or inhibitory to other microbes

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11
Q

Antibiotics can inhibit what in microbes?

A

Steps in metabolic processes

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12
Q

Are antibiotics specific? What does that mean for effectiveness?

A

Antibiotics are specific

They are inhibitory only to microorganisms dependent on affected metabolic process

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13
Q

Narrow-spectrum antibiotics

A

Effective only against a limited number of pathogens

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14
Q

Broad-spectrum antibiotics

A

Attack many different kinds of bacteria

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15
Q

Cidal

A

Antibiotics that kill microorganisms

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16
Q

Static

A

Antibiotics that inhibit growth only

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17
Q

Useful antibiotics act against ___ ___ and not ___ ___.

A

Pathogenic microorganisms

Body cells

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18
Q

First medically useful antibiotic

A

Penicillin

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19
Q

Penicillin is produced by what 2 species of fungus?

A

Penicillium notatum

Penicillium chrysogenum

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20
Q

What genus of what bacteria produces antibiotics?

A

Streptomyces

Actinomycetes

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21
Q

Beta lactams: generic name (2)

A

Penicillins

Cephalosporins

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22
Q

Cephalosporins are produced by what type of fungi?

A

Cephalosporium

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23
Q

How do beta-lactams work?

A

Inhibit synthesis of bacterial cell wall peptidoglycan

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24
Q

Macrolides: generic name

A

Erythromycin

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25
Q

Macrolides (erythromycin) are produced by what bacteria?

A

Streptomyces erythreus

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26
Q

How do macrolides work?

A

Inhibit rRNA associated with the 50S ribosome

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27
Q

Aminoglycosides: generic name (3)

A

Streptomycin
Neomycin
Gentamicin

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28
Q

Streptomycin is produced by what bacteria?

A

S. griseus

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29
Q

Neomycin is produced by what bacteria?

A

S. fradiae

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30
Q

Gentamicin is produced by what bacteria?

A

Micromonospora purpurea

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31
Q

How do aminoglycosides work?

A

Inhibit 30S ribosome function

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32
Q

Tetracyclines: generic name

A

Tetracycline

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33
Q

Tetracycline is produced by what bacteria?

A

S. aureofaciens

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34
Q

How do tetracyclines work?

A

Inhibit binding of aminoacyl-t RNAs to ribosomes

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35
Q

2 antibiotic-producing microbes used in cross-streak plate experiment

A

Penicillium notatum

Streptomyces griseus

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36
Q

4 bacteria tested in cross-streak plate experiment

A

Escherichia coli
Bacillus subtilis
Staphylococcus aureus
Micrococcus luteus

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37
Q

Kirby-Bauer method uses what 4 things to test for antibiotic sensitivity?

A

Standardized inoculum
Mueller-Hinton or Trypticase soy agar plates
High potency antibiotic discs
Exact measurement of inhibition zone

38
Q

Minimal inhibitory concentration of antibiotic: how measured

A

Diameter of zone of growth inhibition around disc when placed on lawn of bacteria

39
Q

Minimal inhibitory concentration of antibiotic: what is it

A

Lowest concentration of antibiotic that will prevent growth of a particular microorganism

40
Q

Minimal inhibitory concentration of antibiotic provides a measure of what

A

Susceptibility of microorganism to antibiotic

41
Q

McFarland standards are used for what purpose in antibiotic sensitivity testing?

A

Standardize bacterial inoculum used for antibiotic sensitivity testing

42
Q

McFarland standards adjusts what?

A

Turbidities of bacterial cultures to be tested

43
Q

What McFarland standard were bacterial cultures adjusted to in antibiotic sensitivity experiment? This is comparable to a bacterial suspension of how many CFU/mL?

A

0.5

10^8 CFU/mL

44
Q

Horizontal gene transfer

A

Process by which genes are transferred from one mature, independent organism to another

45
Q

3 mechanisms of horizontal gene transfer in prokaryotes

A

Conjugation
Transformation
Transduction

46
Q

Conjugation

A

Genetic transfer by direct cell-cell contact between donor and recipient cells

47
Q

Transformation

A

Free DNA is taken up by a cell and integrated into its genome

48
Q

Transduction

A

Transfer of genes between prokaryotic cells by bacteriophages

49
Q

In transformation, competent cells can do what?

A

Take up high molecular weight DNA across cell wall and plasma membrane

50
Q

How transformation produces genetic diversity

A

DNA from donor strain contains different phenotypic characteristics: recipient integrates DNA through genetic recombination, then displays those phenotypic characteristics

51
Q

Genus and species of bacteria used in transformation experiment: naturally or artificially competent, environment

A

Acinetobacter calcoaceticus
Naturally competent
Soil and water

52
Q

Donor vs recipient strains of Acinetobacter calcoaceticus: designation and what gene DNA encodes

A

Donor: Streptomycin-resistant (Str^r)
Recipient: Streptomycin-sensitive (Str^s)

53
Q

Detergent used in transformation experiment to release DNA from donor Acinetobacter calcoaceticus

A

Sodium dodecyl sulfate

54
Q

Is conjugation used to transfer large segments of bacterial chromosome, plasmids, or both?

A

Can be both

55
Q

R factors

A

Plasmids that encode antibiotic resistance genes

56
Q

Conjugative plasmid transfer occurs from donor designated ____ to recipient.

A

tra

57
Q

Some tra genes in conjugative plasmid transfer encode what type of pilus? What does this pilus do?

A

F (sex) pilus

Mediates contact between donor and recipient

58
Q

Steps of conjugative plasmid transfer (5)

A
  1. Donor and recipient cells are drawn together
  2. Formation of channel through which plasmid DNA is transferred
  3. Plasmid DNA is cut at origin of transfer (oriT)
  4. Cut strand is transferred to recipient with simultaneous synthesis of new complementary strands via rolling circle replication
  5. Ends of strands are ligated to form complete plasmids in both donor and recipient cells
59
Q

Conjugation experiment utilized what plasmid?

A

pBBR1MCS-2

60
Q

Plasmid pBBR1MCS-2 encoded what 4 genes?

A 
Kanamycin resistance gene 
lacZ gene (beta-galactosidase)
mob region (region for conjugation)
Multiple cloning site (contained numerous restriction sites)
61
Q

Restriction sites are recognized by what enzymes that do what?

A

Restriction endonucleases

Cut DNA into pieces

62
Q

What genus and species of bacteria was used in conjugation experiment?

A

E. coli

63
Q

Donor strain of E. coli in conjugation experiment was designated what? It contained what genes for what purpose? Sensitive to what antibiotic, but resistant to what antibiotic?

A

S17-1
tra genes for plasmid transfer
Sensitive to nalidixic acid
Resistant to kanamycin

64
Q

Recipient strain of E. coli in conjugation experiment was designated what? Sensitive to what antibiotic, but resistant to what antibiotic through what mechanism? Had mutation in what gene that was complemented by plasmid DNA?

A

DH5alpha
Sensitive to kanamycin
Resistant to nalidixic acid through mutation
Mutation in lacZ gene

65
Q

In conjugation experiment, what substrate was used for beta galactosidase? What color does it produce when hydrolyzed by beta galactosidase?

A

X-gal

Blue

66
Q

Viruses of bacteria are called what?

A

Bacteriophages

67
Q

Bacteriophage is made up of what 2 components?

A

Nucleic acid with protein coating

68
Q

Steps of bacteriophage injection of host cell (2)

A
  1. Phage binds via tail fibers to cell receptor

2. Phage genetic material is injected into bacterial cell

69
Q

What happens in the bacterial cell after being injected with bacteriophage genetic material (2 possible options)?

A
  1. Virus genetic material converts all cell machinery over to manufacture of new virus particles, causing lysis of bacteria
  2. Virus genetic material is inserted into bacterial chromosome, becoming a prophage
70
Q

Bacteriophages whose genetic material brings about lysis of infected cells are referred to as ___ or ___.

A

Lytic

Virulent

71
Q

Bacteriophages whose genetic material is integrated into infected cells are referred to as ___ or ___.

A

Temperate

Lysogenic

72
Q

Prophage

A

Latent form of bacteriophage genome that remains within host but does not destroy it

73
Q

Phage typing

A

Detecting and differentiating certain pathogenic strains of bacteria by their pattern of susceptibility to specific bacteriophages

74
Q

Source material for E. coli bacteriophage

A

Raw sewage

75
Q

E. coli bacteriophages: how separated from bacteria?

A

Filtration

76
Q

Type of E. coli phage used in bacteriophage experiment: name, lytic or lysogenic?

A

T phage

Lytic

77
Q

Phage (viral) titer

A

Concentration of infectious phage particles per milliliter of growth medium

78
Q

How were T phage titers determined in bacteriophage experiment?

A

Serial dilutions of stock phage culture mixed with E. coli and grown on agar plates
Counting zones of clearing (plaques)
Calculating plaque forming units (PFUs) per mL by multiplying average # of plaques counted by dilution factor and dividing that number by volume plated

79
Q

Designation of E. coli strain used in bacteriophage experiment

A

Beta

80
Q

In lysogenic bacteriophage cycle, bacteria infected by masked temperate phages are termed ___ bacteria. Do they show overt evidence of infection?

A

Lysogenic

No overt evidence of infection

81
Q

Name of temperate bacteriophage that infects E. coli

A

Lambda

82
Q

Can lambda bacteriophage only enter lysogenic cycle?

A

No-can enter either lytic or lysogenic

83
Q

What type of protein prevents lambda bacteriophage from entering lytic cycle? How does it do this?

A

Repressor protein called cI

Maintains prophage DNA in integrated state with bacterial DNA

84
Q

Name of the lambda DNA site at which repressor protein cI binds

A

Operator

85
Q

Lysogenic cells are referred to as ____.

A

Immune

86
Q

Superinfection: what is it, how is it prevented

A 
Subsequent bacteriophage infection of a lysogenic bacterium
Protein repressor (like cI) prevents expression of all DNA molecules of the same type of immunity region regardless of whether they are integrated into the host chromosome
87
Q

Resistance to bacteriophages: how it works

A

Phage is prevented from absorbing or from injecting DNA into the cell or is blocked at some other stage of the lytic cycle

88
Q

Cro: what is it, what cycle does it promote in lambda phage

A

Regulatory protein

Lytic cycle

89
Q

Does Cro bind to same or different operator sites as cI?

A

Same

90
Q

Between cI and Cro, which binds more weakly and must rise to a higher level to exert its effects?

A

Cro

91
Q

Phage attachment to receptors on the surface of bacterial cells is facilitated by the presence of ____ ____.

A

Magnesium ions

Microbiology (24 decks)

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