BIO14 exercises 11, 12, 25, and 26

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Microbiology
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LAB Final exam
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1

Consist of only one species of microorganisms, needed to characterize and identify microbes

Pure culture

2

More than one microorganisms growing in the culture

Mixed culture

3

The presence of unwanted microorganism

Contamination

4

a loop is used streak the mixed sample many times over the surface. Use an inoculation loop and dip in the same sample then streak it across the petri dish in a zig-zag motion. The theory is that the bacteria will fall off one by one and grow into a colony. This is the most common isolation technique.

Streak plate technique

5

The antimicrobial drugs with the broadest spectrum of activity are

tetracyclines.

6

A small amount of diluted specimen is spread over a surface of a solid medium using a spread rod.

Spread plate technique

7

Contain various nutrients that allow one to distinguish one bacteria from another by how they metabolize the media with a waste product.

Differential Media

8

How would you determine whether a colony was a contaminant on a streak plate

A contaminant would be one growing in an area where you did not streak.

9

What would happen if the plates were incubated a week longer

TNTC - too numerous to count

A month- None will be isolated if a month

10

Chemicals used on living tissues to decrease the number of microbes

Antiseptics

11

Inhibits nucleic acid synthesis

Ciprofoxacin

12

Is hot oven or incinerators. They denature enzymes, dehydrate microbes, and kills by oxidative effects. Standard application is 170 *C for 2 hours.

Dry heat

13

Inhibits cell wall synthesis by preventing cross-linking of peptidoglycan

Penicillin

14

Is 63-degree Celsius for 30 minutes or 72 degrees Celsius for 15 seconds killing pathogenic organism or those that cause spoilage?

Pasteurization

15

If turns yellow then it is _____________________

S. Aureus

16

Cause temporary inhibition to bacterial growth

Bacteriostatic agents

17

Is the disk - diffusion technique measuring bacteriostatic or bactericidal activity? Briefly explain.

Measuring bacteriostatic because instead of killing the microorganisms, they inhibit microbial growth.

18

A substance produced by a microorganism that inhibits the growth of another.

Antibiotic

19

What is the purpose of peptone in the media?

The Peptone is use as a nutrition source of carbon, nitrogen and energy for growth.

20

What is the purpose of agar in the media

Agar is used to solidify the bacteria in the media

21

What is the advantage of using Mueller-Hinton Agar

It allows the antimicrobial agent to diffuse freely.

22

Zone of inhibition

The area around the disc where bacteria does not grow.