Laboratory Experiments in Microbiology-Exercise 3 Flashcards


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created 10 years ago by mermaidsmom
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Handling bacteria
updated 10 years ago by mermaidsmom
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microbiology 203a
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1

What are aseptic techniques?

are procedures used to avoid introducing unwanted microbes and to prevent spreading microbes where they are not wanted.

2

Who successfully transferred Bacillus anthracis and Mycobacterium tuberculosis between diseased animals and laboratory media?

Robert Koch

3

What is an inoculating loop?

is a Nichrome wire held with and insulated handle.
It is used for transferring bacteria between library media and microscope slides.

4

The inoculating loop is sterilized by?

Heating or flaming - in in flame until the loop is red hot

5

What were the first bacteria cultures grown in?

broth (liquid) such as infusions and blood

6

What were the first solids used to grow cultures?

potato starch, coagulated egg white and meat

7

What did Robert Koch use?

gelatin

8

Who suggested agar to Koch?

Angelina Hess

9

Do you sterilize an inoculating loop before or after the transfer of bacteria?

both- in the hottest part of the flame

10

What do you call a medium whose exact chemical composition is known?

chemically defined medium

11

What is a complex media?

media for which the exact chemical composition varies slightly from batch to batch

12

Organic carbon, energy, nitrogen sources are usually supplied by ____________________ and________.

protein in the form of meat extracts and partially digested proteins called peptones.

13

Nutrient broth is?

liquid complex medium-when agar is added it becomes a solid medium called nutrient agar

14

What is agar?

marine red algae
liquefies at 100*C

15

Media must be sterilized after preparation true or false?

true

16

What is the most common method of sterilizing culture media that are heat stable?

steam sterilization or autoclaving
process by which it is steamed under pressure heated to 121*C at 15 pounds of pressure (psi)
for 15 minutes

17

How do you store a sample in a petri dish?

upside down with the agar at the top otherwise moisture will form

18

What does inoculated mean?

that microbes will be intentionally introduced onto nutrient agar and into nutrient broth

19

What do you call the time that bacteria are inoculated into culture media and they increase?

incubation period

20

When liquid media becomes turbid it is__________.

cloudy

21

What is a colony?

a population of cells that arises from a single bacterial cell.

22

A colony-forming unit is?

A colony may arise from a group of the same microbes attached to one another.

23

Bacterial growth in broth

1. clear no bacteria
2. turbid-cloudy
3. pellicle and turbid- cloudy and a film
4.flocculent-chunks suspended
5. sediment- bottom

24

What is TNTC?

too numerous to count

25

You use a loop or needle with?

Liquid-nutrient broth/ loop or needle
solid- agar slant- loop or needle zig-zag when inserting bacteria
semi-solid (agar deeps) needle/stab streak

26

What are bacteria using for nutrients in nutrient agar?

peptones or meat extracts

27

Why do some bacteria go to top?

They thrive in oxygen and oxygen is richer at the top

28

Purpose of agar deeps?

to determine motility and to culture bacteria that require a lower core of oxygen