Final Micro Quiz

Front 1

What occurs when a T helper cell is activated?

Back 1

It begins to produce cytokines that function to direct further immune responses.

Front 2

What do T Cell Receptors (TCRs), the antigen receptors on T cells, bind? How does this differ from an antigen receptor on a B cell?

Back 2

TCRs bind antigenic peptides that have been processed and presented on the surface of cells in association with the MHC molecules. B cell antigen receptors can bind antigens directly.

Front 3

In the T Cell Activation Assay, what is KZH and how was it created?

Back 3

KZH is the T helper hybridoma used in the experiment. It was created by fusing normal T helper cells from mice immunized with the antigen lysozyme with a T lymphoma cell that was stably transfected with a reporter construct.

Front 4

KZH cells have the reporter gene ______ (which encodes _______) under the control of a promoter for the cytokine _____ gene.

Back 4

1. lacZ

2. b-galactosidase

3. IL-2

Front 5

In a resting state, does KZH express the IL-2 gene? Does it express the lacZ gene?

Back 5

No and no

Front 6

What would cause KZH cells to transcribe the IL-2 gene and the lacZ gene?

Back 6

If it is activated by the appropriate antigenic peptide/MHC combination.

Front 7

What was the purpose of using Triton X-100 in the T cell assay?

Back 7

Triton X-100 is a detergent that was used to lyse the cells before adding the CPRG to detect B-gal activity.

Front 8

Why was chlorophenol red galactoside added to the T cell assay?

Back 8

Chlorophenol red galactoside (CPRG) turns from yellow to red when it is hydrolyzed by B-gal. So it would indicate T helper cell activation due to antigen presence.

Front 9

What was the antigen used in the T cell activation assay? What was used to process it and create peptides to present to the T cell receptor?

Back 9

Antigen was lysozyme. Antigen-presenting mouse B cell hybridoma LK35.2 was used - B cells took up and processed lysozyme and presented the peptides to KZH TCR using MHC Class II.

Front 10

Why was a CO2 incubator used in the T cell activation assay?

Back 10

It was used to culture the KZH and LK35.2 cells because it establishes equilibrium with bicarbonate in the growth medium, forms buffer that maintains a pH of 7.4 to support optimum growth.

Front 11

Why did the cells have to be pelleted and supernatant removed before the T cell activation assay was performed?

Back 11

Because the phenol red dye contained in the medium interferes with the assay - its color in alkaline sol'n is similar to the color produced by hydrolysis of the chromogenic substrate used.

Front 12

The first medically useful antibiotic was ______, which is produced by what two filamentous strains of fungi?

Back 12

Penicillin - penicillium notatum and penicillium chrysogenum

Front 13

What bacterial genus are most currently useful antibiotics derived from? What are a couple examples?

Back 13

Streptomyces - examples are streptomycin, kanamycin, vancomycin, rifampin

Front 14

What were the two antibiotic-producing strains used in lab for the action of antibiotics lab?

Back 14

Penicillium notatum and Streptomyces griseus

Front 15

What four bacteria were plated onto the antibiotic-producing strain plates to test for antibiotic sensitivity?

Back 15

E. coli, B. subtilis, S. aureus, and M. luteus

Front 16

How was the inhibition zone measured on the yeast-malt extract agar plates?

Back 16

Millimeters from center streak to growth of bacteria

Front 17

What is the Kirby-Bauer method?

Back 17

It is a diagnostic tool to measure the inhibitory effect of antibiotics on bacterial growth using antibiotic discs on Mueller-Hinton agar or TSA plates.

Front 18

What is the MIC?

Back 18

The minimal inhibitory concentration is the lowest concentration of antibiotic that will prevent the growth of a particular microorganism. Measured in the diameter of the zone of growth inhibition around the antibiotic disc on the plate.

Front 19

What are McFarland standards? Why are they used?

Back 19

They are turbidities of bacterial cultures and they are used to standardize the bacterial inoculum used for antibiotic sensitivity testing.

Front 20

What McFarlane standard was used in the ANtibiotic Sensitivity Disc Diffusion test?What bacterial suspension was this comparable with?

Back 20

0.5, comparable to a bacterial suspension of 10^8 CFU/mL

Front 21

What four antibiotic discs were used in the antibiotic sensitivity disc diffusion test?

Back 21

Eryhtromycin, Penicillin, Tetracycline, Gentamicin

Front 22

What two bacteria were used antibiotic disc diffusion test

Back 22

S. aureus and E. coli

Front 23

What is conjugation?

Back 23

Conjugation is th eprocess of genetic transfer that involves cell to cell contact between donor and recipient cells

Front 24

What is transformation

Back 24

Transformation (horizontal gene transfer) is the process in which a piece of free DNA is taken up by a cell and integrated into its genome.

Front 25

What is transduction?

Back 25

Transduction is the transfer of genes between bacterial or archaeal cells by viruses known as bacteriophages.

Front 26

What was the product of bacterial transformation in Exercise 13?

Back 26

A crude bacteria extract of streptomycin-resistant (Str^r) culture of Acinetobacter calcoaceticus

Front 27

What is the natural habitat of Acinetobacter calcoaceticus

Back 27

Soil and water. It is a naturally competent bacteria

Front 28

What if bacterial growth was observed in the fourth sector with the DNA control in Ex. 13?

Back 28

It would mean that the DNA preparation was not sterile and therefore the results of the experiment are not reliable.

Front 29

What is an R factor?

Back 29

Conjugative plasmids that carry genes for resistance to antibiotics.

Front 30

How does conjugative plasmid transfer occur?

Back 30

A donor bacterium containing the plasmid carrying the genes tra transfer the plasmid to a recipient, which lacks the plasmid.

Front 31

What structure do some tra genes encode that mediates conjugative plasmid transfer?

Back 31

An F (sex) pilus, which mediates the contact between donor and recipient.

Front 32

HOw is the plasmid DNA transferred to the recipient?

Back 32

A channel forms when the cells are drawn together - one plasmid DNA strand is cut at a region known as the origin of transfer (oriT) and transfer of the cut strand to the recipient with simultaneous synthesis of new complementary strands via rolling circle mechanism. Strand ends are ligated.

Front 33

What is oriT?

Back 33

The origin of transfer region in a plasmid, the DNA is cut at this site to initiate transfer and synthesis of new complementary DNA

Front 34

What plasmid was studied in the Bacterial Conjugation exercise?

Back 34

pBBR1MCS-2

Front 35

What are the four key features of plasmid pBBR1MCS-2?

Back 35

1. Kanamycin resistance gene (Kan^r)

2. lacZ gene which encodes B-gal

3. A region required for conjugation called mob (mobilization)

4. A multiple cloning site (MCS) with numerous restriction sites.

Front 36

What does beta galactosidase do?

Back 36

It is an enzyme that hydrolyzes lactose to glucose and galactose.

Front 37

What E coli donor strain was used in the bacterial conjugation exercise?

Back 37

S17-1 - has tra genes for plasmid transfer, is sensitive to nalidixic acid, is resistant to kanamycin due to presence of plasmid.

Front 38

What recipient strain was used in the bacterial conjugation experiment?

Back 38

DH5a (alpha) - sensitive to kanamycin, resistant to nalidixic acid due to natural mutation of chromosomal gene. Also has mutation in chromosomal lacZ gene that can be complemented by the lacZ gene on the plasmid.

Front 39

Why was X-gal used in the bacterial conjugation experiment?

Back 39

It is a substrate for B-galactosidase that hydrolyzes X-gal, forming an intense blue precipitate. LacZ activity = blue colony color

Front 40

What are the steps of lytic bacteriophage infection of a host cell?

Back 40

1. Binding of the phage to a cell receptor via tail fibers.

2. Genetic material is injected into the cell from the capsid head

3. Virus nucleic acid converts all cell machinery to manufacture new virus, causing lysis of the bacteria

Front 41

What are the steps of temperate bacteriophage infection of a host cell?

Back 41

1. Binding of the phage to a cell receptor via tail fibers.

2. Genetic material is injected into the cell from the capsid head

3. The virus nucleic acid physically inserts its genome into the bacterial chromosome and becomes a prophage

Front 42

What is a prophage?

Back 42

The latent form of the virus genome that remains within the host, but does not destroy the host.

Front 43

What is phage typing?

Back 43

The marked specificity of a bacteriophage for a particular host has provided the means to detect and differentiate certain pathogenic strains of bacteria by their susceptibility to bacteriophages.

Front 44

Bacteriophages can mediate transduction, which is __________

Back 44

where they mediate the transfer of bacterial DNA between bacteria

Front 45

What is a "coli phage" ?

Back 45

Some of the best known viruses/phages which attack E. coli

Front 46

What is the source material for the isolation of E. coli bacteriophage?

Back 46

Raw sewage

Front 47

What was contained in the pellet and what was contained in the supernatant after the phage/E. coli culture was centrifuged?

Back 47

Pellet was bacterial cells/debris, supernatant contained the phage

Front 48

What was the purpose of adding chloroform to the supernatant?

Back 48

It killed any contaminating bacteria but does not harm bacteriophage

Front 49

What are "plaques"

Back 49

The zones of clearing in an otherwise dense lawn of E. coli due to the localized areas of lysis of phage-infected bacteria

Front 50

What does penicillin inhibit?

Back 50

Growth of gram positive organisms

Front 51

What does streptomyces inhibit?

Back 51

Growth of all bacteria at varying levels

Front 52

How are restriction sites on a plasmid recognized?

Back 52

By restriction endonucleases, enzymes that can cut DNA into fragments.

Front 53

(Transformation) If DNA taken up is derived from _________, such DNA can be recombined with chromosomal DNA, which is also located in the cytoplasm.

Back 53

The same or closely related species

Front 54

What is a competent cell?

Back 54

A cell capable of taking up high molecular weight DNA derived from the same or closely related species

Front 55

Why was Acinetobacter used specifically?

Back 55

Because it is a naturally competent bacteria

Front 56

What was the detergent used to lyse the cells in the Transformation experiement ? (ex 13)

Back 56

0.05% sodium dodecyl sulfate in "standard saline citate" (0.15 M NaCL, 0.015 M Na3 citrate).

Front 57

Why are B-lactams (antibiotics) more effective in inhibiting gram-positive bacteria?

Back 57

Because they inhibit the synthesis of bacterial cell wall (peptidoglycan)

Front 58

What is the generic name for B-lactam?

Back 58

Penicillin or Cephalosporin

Front 59

What is the biological source of B-lactam antibiotics?

Back 59

Penicillium spp. or cephalosporin spp.

Front 60

What is the generic name of Macrolides?

Back 60

Erythromycin

Front 61

What is the biological source of macrolides?

Back 61

Streptomyces erythreus

Front 62

What is the mode of action of macrolides?

Back 62

Inhibit rRNA associated with the 50S ribosome

Front 63

What is the generic name for aminoglycosides? (3)

Back 63

Streptomycin, Neomycin, gentamicin

Front 64

What is the biological source of aminoglycosides?

Back 64

S. griseus, S. fradiae, Micromonospora purpurea

Front 65

What is the mode of action of aminoglycosides?

Back 65

Inhibits 30S ribosome function

Front 66

What is the generic name for tetracyclines?

Back 66

Tetracycline

Front 67

What is the biological source of tetracycline?

Back 67

S. aureofaciens

Front 68

What is the mode of action for tetracycline?

Back 68

Inhibits binding of aminoacyl-t RNAs to ribosomes

Front 69

In the T cell activation assay, how was B-galactosidase activity measured?

Back 69

By the hydrolysis of the chromogenic substrate chlorophenol red galactoside (CPRG).

Front 70

In the bacteriophage experiment, why were magnesium ions contained in the LB broth?

Back 70

Phage attachment to receptors on the surface of bacterial cells was facilitated by the presence of magnesium ions.