Biol 202 Lab Practical 1

Question 1

Growth media

Answer 1

liquid or solid components used to grow microorganisms.

Question 2

Culture

Answer 2

A batch of microorganisms grown for the purpose of future testing

Question 3

Fire sterilization

Answer 3

The use of heat to sterilize a tool used in the lab that comes into contact with microorganisms

Question 4

Culture purity

Answer 4

The presence of only one microorganism within a culture

Question 5

Inoculation

Answer 5

The transfer of microorganisms using aseptic technique

Question 6

Mixed culture

Answer 6

The presence of two or more microorganisms within a culture

Question 7

TSB and TSA (What do they stand for?)

Answer 7

TSA: tryptic soy ager
TSB: tryptic soy broth
(the only difference is ager which solidifies the broth)

Question 8

Continuous streak

Answer 8

A method of spreading microbes that involves “S” shapes along the entire plate that do not overlap

Question 9

Colony

Answer 9

A grouping of microorganisms on a plate originating from one single cell large enough to be seen by the naked eye

Question 10

Culture form (4 different types)

Answer 10

Circular
Irregular
Filamentous
Rhizoid

Question 11

Culture elevations (5 Different types)

Answer 11

Raised
Convex
Flat
Umbonate
Crateriform

Question 12

Culture margins (5 different types)

Answer 12

Entire
Undulate
Filiform
Curled
Lobate

Question 13

Quadrant Streak plating

Answer 13

Useful when trying to create and isolate down to one viable colony. (zig zag then drag once into next, zig zag then drag into next.)

Question 14

Lawn

Answer 14

Multiple bacterial colonies overlapping

Question 15

Culture titer

Answer 15

The exact amount of cells in a serial dilution

Question 16

Serial dilution

Answer 16

A dilution that takes place over a series of dilutions

Question 17

Aliquot

Answer 17

A set volume of solution after dilution

Question 18

Titer Equation

Answer 18

Titer = DF x N x P

Question 19

What is one micro liter equal to?

Answer 19

100uL = 0.1mL

Question 20

Simple staining technique

Answer 20

Simple staining technique: technique used to identify bacteria that would otherwise be naturally clear

Question 21

What magnification is necessary to view bacteria on a microscope?

Answer 21

Highest microscope magnification: 100x (in immersion oil)

Question 22

Differential stain

Answer 22

A stain that distinguishes two different types of bacteria (typically gram + and -)

Question 23

Gram stain (step 1 and 2)

Answer 23

1. Fixation - heating the sample bacteria slide
2. Primary stain - is crystal violet, that’s positively charged that interact with negatively charged ions in the cell. The cell begins to appear purple

Question 24

Gram stain (Step 3-4)

Answer 24

3. Iodine treatment (mordant) - treat the cells with iodine. This iodine reacts with crystal violet within the cell wall and becomes trapped, so the color does not disappear.
4. Decolorizer - most important step. Insert ethanol and if done properly, G- cells will lose their purple color first because of thin cell walls. G+ cells do not as their walls are thicker and this allows us to distinguish them.

Question 25

Gram stain (step 5)

Answer 25

5. Counter stain - done with safranin (positively charged dye) this stains the G- cells and leaves the G+ cells purple

Question 26

Gram + (Characteristics)

Answer 26

G+ - Thick cell wall - Many layers of peptidoglycan - No outer membrane - Turns pink

Question 27

Gram - (Characteristics)

Answer 27

G- - Thin cell wall - Few peptidoglycan layers - LPS layer - Turns pink

Question 28

What must a media provide (6 elements)

Answer 28

A media must provide - Carbon - Energy - Electrons - Nitrogen - Trace minerals - Growth factors

Question 29

Robust organisms (What do they require?)

Answer 29

Robust organisms - Very minimal growth requirements

Question 30

Fastidious organisms (What do they require?)

Answer 30

Fastidious organisms: - Require many growth factors in organic compounds for growth but cant be synthesized

Question 31

Autotrophs & Heterotrophs (What do they require?)

Answer 31

Autotrophs - Able to make their own organic compounds for growth Heterotrophs - Organisms that cant synthesize an organic compound needed for their growth

Question 32

Defined vs complex media (What are they?)

Answer 32

Defined vs complex media - Defined: we know what is on the media plate - Complex: we dont know what's on the plate

Question 33

Selective vs differential media (What are they?)

Answer 33

Selective vs differential media - Selective: used to grow one specific type of organism no others - Differential: does not inhibit growth of anything but instead allows you to contrast their interactions with media components

Question 34

EMB Agar (What is it used for?)

Answer 34

EMB agar: used for the isolation of fecal colonies - Fecal colonies: organisms used as indicators of contamination and will produce fermenting sugar lactose and acid gas - Can inhibit G+ - Fecal coliforms are different from coliforms based on the intense colour change due to fermentation

Question 35

EMB agar (what Colors can it turn?)

Answer 35

- Dark purple with metallic green shine means there are coliforms present - No change means there are none present

Question 36

MacConkey's agar (What is it used for?)

Answer 36

MacConkey's agar - Used to distinguish non lactose fermenters from lactose fermenters

Question 37

MacConkey's agar (What colors can it turn?)

Answer 37

- Red on the plate means lactose fermenting - No color means non lactose fermenting

Question 38

Blood ager (What can it tell us?)

Answer 38

Blood agar - Capable of distinguishing between organisms that can and cant lyse red blood cells - Hemolysis: can lyse red blood cells ○ Alpha: partial or incomplete lysing ○ Beta: complete lysing of RBC ○ Gamma: no lysing activity

Question 39

What are the three hemolysis patterns

Answer 39

Alpha: partial or incomplete lysing Beta: complete lysing of RBC Gamma: no lysing activity

Question 40

MSA (What is it used for?)

Answer 40

MSA - Contain sodium chloride - Used for identifying staphylococcus aureus ○ Because it can grow at high salt ○ Because it can secrete acid that changes the phenol red to pink to yellow

Question 41

MSA (What colour does it turn?)

Answer 41

Changes the phenol red to pink to yellow.

Question 42

Antiseptics

Answer 42

Antiseptics: used on living tissue

Question 43

Disinfectants

Answer 43

Disinfectants: used on non living surfaces (more toxic)

Question 44

Antibiotics

Answer 44

Antibiotics: anti-microbial agent that can be topical or ingested by patient

Question 45

How can disinfectants inhibit bacteria?

Answer 45

- The way each of these affect material growth differs from ○ Cell membrane breakdown ○ Stopping protein synthesis ○ Damaging nucleic acids ○ Altering growth cycles

Question 46

Zone of inhibition (What is it and its two types?)

Answer 46

- Zone of inhibition: larger the zone of inhibition the greater the effectiveness of the compound ○ Bactericidal: kill organisms ○ Bacteriostatic: they inhibit growth

Question 47

Is a larger inhibition zone better?

Answer 47

Yes it means there is more stoppage of bacterial formation

Question 48

Do you sterilize the inoculation loop in between quadrant streak quadrants?

Answer 48

Yes or you will end up with a continuous streak

Question 49

Fecal coliform (What is it)

Answer 49

It is a gram negative colony of bacteria that can ferment lactose (and cause a reaction with the right media)

Question 50

Can a media be simple and differential at the same time?

Answer 50

Yes, if the media can select to only grow one type of organism yet display the difference between two bacteria it is technically both.