6 - Growth

Question 1

Obligate

Answer 1

requires

Question 2

Facultative

Answer 2

doesn’t require, but can have it

Question 3

Thermophiles

Answer 3

heat loving

Question 4

Mesophiles

Answer 4

moderate-temperature loving

Question 5

Psychrophiles

Answer 5

cold loving

Question 6

Do bacteria do better above or below their optimal temperature?

Answer 6

below

Question 7

What group do most pathogens belong to?

Answer 7

Mesophiles

Question 8

What group are food spoilers that slowly degrade food?

Answer 8

psychotrophs

Question 9

Does refrigeration kill most bacteria?

Answer 9

it does not kill most microbes, but does keep them from growing

Question 10

What pH do most bacteria like?

Answer 10

6.5-7.5

Question 11

What pH do molds/yeasts prefer?

Answer 11

5-6

Question 12

What is a halophile?

Answer 12

salt loving

Question 13

Extreme halophiles

Answer 13

grow in high salt concentrations

Question 14

Obligate halophiles

Answer 14

require high salt to grow

Question 15

Facultative halophiles

Answer 15

don’t require but can grow at high salt concentrations

Question 16

Aerobe

Answer 16

use oxygen in energy reactions

Question 17

Anaerobe

Answer 17

do not use oxygen

Question 18

Aerotolerant anaerobes

Answer 18

Can’t use oxygen for growth, but can tolerate it

Question 19

Microaerophiles

Answer 19

require oxygen in small amounts

Question 20

obligate aerobes

Answer 20

require oxygen to live

Question 21

facultative anaerobes

Answer 21

use oxygen but can grow w/o by fermentation or anaerobic respiration

Question 22

T/F organisms that use oxygen will produce toxic forms of oxygen so it must have enzymes to break down the toxic forms

Answer 22

true

Question 23

What enzymes are responsible for breaking down toxic oxygen?

Answer 23

1. superoxide dismutase (SOD)
2. catalase

Question 24

What is culture media?

Answer 24

nutrient material used to grow microbes in lab (initially sterile)

Question 25

Agar

Answer 25

solidified medium polysaccharide from algae (sterile)

Question 26

Inoculum

Answer 26

microbes introduced into medium

Question 27

Culture

Answer 27

microbes growing in medium

Question 28

What are the six types of media?

Answer 28

1. chemically defined media 2. complex media 3. reducing media 4. selective media 5. differential media 6. enrichment media

Question 29

Chemically defined media

Answer 29

exact composition is known (so many g of this or that) must contain energy and carbon source for specific microbe

Question 30

Complex media

Answer 30

extracts from yeast, meat, plants (exact composition varies from batch to batch) - extracts provide growth factors and vitamins - is the most common

Question 31

Reducing media

Answer 31

for anaerobes, have ingredients that combine with and deplete oxygen (tightly capped tubes)

Question 32

Selective media

Answer 32

suppress growth of unwanted and encourage growth of desired microbes

Question 33

Differential media

Answer 33

can grow everything but some microbes look different than others allowing for distinction of colonies

Question 34

Enrichment media

Answer 34

media specific for a microbe, used to increase numbers of an organism - as much bacteria as fast as you can

Question 35

What is a colony?

Answer 35

group of multiple cells of the same microbe attached together - that originate from one single cell (all cells in colony are identical)

Question 36

What is the purpose of a streak plate?

Answer 36

to get single colonies

Question 37

How do you perform a streak plate

Answer 37

sterilize, spread, repeat x4 (sterilize 5x and make sure you draw back through the previous quadrant)

Question 38

How do bacteria cells divide?

Answer 38

Reproduction: binary fission

Question 39

Bacteria growth curve stages:

Answer 39

1. lag 2. log 3. stationary

Question 40

What happens at the lag stage of the growth curve?

Answer 40

beginning of growth

Question 41

What happens at the log stage of the growth curve?

Answer 41

cells divide, logarithmic increase

Question 42

What happens at the stationary stage of the growth curve?

Answer 42

growth rate slows and reaches equilibriums (death starts from depletion of nutrients, buildup of waste, pH change and more)

Question 43

What happens at the death stage of the growth curve?

Answer 43

death exceeds the new cells, logarithmic decrease

Question 44

What are the methods used to count/quantify bacteria?

Answer 44

1. plate counts 2. MPN 3. direct microscopic count 4. Coulter counter 5. Turbidity 6. Metabolic activity 7. Dry weight

Question 45

Plate counts

Answer 45

bacteria on plate and count colonies

Question 46

Spread plate method

Answer 46

bacteria culture is added on top of solidified agar plate (bacteria grown ON TOP of agar)

Question 47

Pour plate method

Answer 47

bacteria in media is added to liquid agar and solidified (bacteria grow WITHIN agar)

Question 48

MPN

Answer 48

- most probable number - rough estimate how many bacteria is in the sample - good for bacteria that don't grow on a solid medium

Question 49

Direct microscopic count

Answer 49

fast, sample placed on marked slide, physically counts bacteria

Question 50

Coulter counter

Answer 50

electronic counters (used in research and hospitals) and counts bacteria for you

Question 51

Turbidity

Answer 51

more bacteria in culture = more cloudy or turbid - can be tested with spectrophotometer

Question 52

Metabolic activity

Answer 52

measures the amount of waste being made

Question 53

Dry weight

Answer 53

filamentous bacteria and fungi can be removed from medium, filtered, dried, and weighed

Question 54

Which organism is killed by atmospheric oxygen?

Answer 54

obligate anaerobe

Question 55

How many cells would be present after 4 generations if we started with 3 cell?

Answer 55

48

Question 56

Which of the following is NOT a possible reason why exponential growth stops? a. accumulation of waste products b. exhaustion of nutrients c. harmful change in pH d. all of these are possible reasons

Answer 56

D

Question 57

A spectrophotometer can be used to measure

Answer 57

turbidity