Old Material Study

Question 1

What is the aseptic technique?

Answer 1

The technique of heating tools to keep them free of unwanted contaminants or microbes.

Question 2

What is a chemically-defined media?

Answer 2

A culture medium whose exact chemical composition is known.

Question 3

What is a complex media?

Answer 3

A medium which varies in composition from batch to batch.

Question 4

What is the purpose of the streak plate technique?

Answer 4

To allow individual cells to grow into separate colonies so that they can be removed and subcultured for other experiments.

Question 5

What is a sign of growth in broth or in agar?

Answer 5

In broth: turbidity

In agar: colonies

Question 6

What is the formula for total magnification?

Answer 6

(ocular lens) x (objective lens)

Question 7

What is the total magnification of oil immersion lens?

Answer 7

1000x

Question 8

What is a smear preparation?

Answer 8

To preserve the structure of a specimen. This kills and fixes them to the slide.

Question 9

What does heat fixation do?

Answer 9

Denatures enzymes, facilitates adherence to a slide, makes cells more permeable and preserves their structure.

Question 10

What is a simple stain?

Answer 10

The use of only on reagent to color all cells the same color.

Question 11

Why do you use a simple stain?

Answer 11

To allow for visualization of cell shape, size, and arrangement.

Question 12

What is a direct, simple stain?

Answer 12

Stains the cell.

Question 13

What is a negative simple stain?

Answer 13

Stains the background, not the cell.

Question 14

What is a differential stain?

Answer 14

Multiple reagents are used to stain cells differently. Allows for differentiation of cells.

Question 15

What are the reagents used for a gram stain?

Answer 15

Crystal violet, iodine, alcohol, and safranin.

Question 16

How is G+ stained in a gram stain?

Answer 16

Crystal violet: violet
Iodine: violet
Alcohol: violet
Safranin: violet

Question 17

How is G- stained in a gram stain?

Answer 17

Crystal violet: violet
Iodine: violet
Alcohol: clear
Safranin: pink

Question 18

What is the purpose of iodine in the gram stain?

Answer 18

To adhere the violet color to the bacteria’s cell membrane.

Question 19

In the endospore stain, what color do the endospores turn?

Answer 19

(using malachite green) Green.

Question 20

In the endospore stain, what color do the vegetative cells turn?

Answer 20

(using safranin) Pink.

Question 21

In the acid fast stain, AF+ turns what color?

Answer 21

Red/pink with each step.

Question 22

In the acid fast stain, AF- turns what color?

Answer 22

Red/pink -> blue.

Question 23

With the capsule stain, what occurs?

Answer 23

A white halo appears around the cell.

Question 24

What type of stain is a capsule stain?

Answer 24

A differential stain.

Question 25

What is a countable plate in the standard plate count technique?

Answer 25

30-300 colonies.

Question 26

How do you calculate # CFU/ml?

Answer 26

#CFUs x DF = #CFU/ml

Question 27

How do you know if the transformation occurred?

Answer 27

The bacteria is glowing green (due to IPTF), and it grew in the media (+DNA).

Question 28

What is the purpose of the heat shock step of a transformation?

Answer 28

It facilitates the entry of DNA into the bacterial cells. The membrane becomes permeable.

Question 29

What was the purpose of the plate with IPTG?

Answer 29

It allows the expression of the GFP protein, which requires IPTG, to demonstrate differential gene expression.

Question 30

What are the steps of the lytic cycle?

Answer 30

1) attachment 2) entry of phage DNA and degradation of host DNA 3) Synthesis of viral genomes and proteins 4) assembly 5) release

Question 31

What is a plaque?

Answer 31

Visual clearings in a lawn of bacterial growth.

Question 32

What is plaque assay used for?

Answer 32

To quantify the number of viruses.

Question 33

What is a zone of inhibition?

Answer 33

The zone in which there is no visible bacterial growth around the antibiotic disk.

Question 34

What is the name of the plate used for antimicrobial susceptibility testing?

Answer 34

Mueller-Hinton agar

Question 35

What is the mm range for resistant bacteria?

Answer 35

less than or equal to 13 mm.

Question 36

What is the mm range for susceptible bacteria?

Answer 36

14-16mm

Question 37

What is the mm range for intermediate bacteria?

Answer 37

Greater than or equal to 17mm.

Question 38

What is a transformation?

Answer 38

When a cell takes up and expresses a new piece of DNA.

Question 39

What is the name of the species that contains mycolic acid in its cell wall?

Answer 39

Mycobacterium

Question 40

What are the two endospore-formers that we learned?

Answer 40

Clostridium and Bacillus

Question 41

Why would we need an old culture of endospore-formers for an endospore stain?

Answer 41

It ensures a stress environment, which is when endospores would likely appear.

Question 42

What is transduction?

Answer 42

The transfer of DNA from one bacteria into another bacteria via a bacteriophage.

Question 43

What is conjugation?

Answer 43

Transfer of DNA material via a pilus. Requires cell-to-cell contact.

Question 44

What do lesions on a leaf indicate?

Answer 44

TMV infection.