Chapter 6 (EXAM 2)

Question 1

Viable count

Answer 1

The number of microorganisms in a particular media that are alive

Question 2

Total count

Answer 2

The number of microorganisms in a media that are both living and dead`

Question 3

Generation time

Answer 3

The time for a cell to divide and population to double; species specific
The rate is always constant \

Question 4

What is the growth curve and its phases

Answer 4

The curve of microorganisms in unnatural environment, not soil or water
Phases are lag, log, stationary and death

Question 5

Lag phase

Answer 5

Little to no division of growth in bacteria
Turn genes on that were silences
Once they’ve gotten enough food they move to next phase

Question 6

Log phase

Answer 6

Exponential increase in population

Industrial producers will create a condition of hemostatic environment(constant)

Question 7

Stationary phase

Answer 7

When resources become scarce, the number of dying cells dont equal the number of cells dividing
At the end you see less growth, organisms are smaller then normal

Question 8

Death phase

Answer 8

Organisms planning for death of population and produce endospores if the bacteria is able to

Question 9

What phases are exponential

Answer 9

Log and death

Question 10

What are plasmids

Answer 10

What bacteria pick up at later stationary phase and beginning of death phase in desperation to survive.
Tiny circles of genetic material that contain genes of resistance

Question 11

What are growth influences of cells

Answer 11

Cells require water bc it aids in diffusion of materials
Like less then 1% salt, about .85 NacI
Applies to most bacteria except staph and hydrophilic archer bacteria can tolerate higher salt solutions

Question 12

what does it mean to be phacotactive

Answer 12

Be on a needs basis with or without salt

Question 13

Isotonic

Answer 13

Same on the outside as it is on the inside

Question 14

Hypertonic

Answer 14

Enviroment is more concentrated in solutes on the outside

Water goes out cell then what’s inside the cell

Question 15

Hypotonic

Answer 15

Solution cell is in is more watery compared to what’s inside of the cell. Cells take more water in

Question 16

Describe psychrophiles

Answer 16

Cold organisms that can live btwn -10 & 20

15 being optimum temp

Question 17

Describe psychrotrophs

Answer 17

Cold loving organism that can go in fridge range in 0-30

25 being optimum temp

Question 18

Describe mesophils

Answer 18

Live within 10-50 range

37 being their fav temp ( body temp)

Question 19

Describe thermophils

Answer 19

Like warm temp. Live in compost piles, dump, heat resistance
Live in 40-72 range, 62 being their fav temp

Question 20

Describe hyperthermophils

Answer 20

Type of archer, extreme bacteria

Like temperature of 67-110, 94 being fav temp

Question 21

Media: broth

Answer 21

Test tubes filled with liquid

Question 22

media: slant

Answer 22

Test tubes with agar at an angle, cuts down contamination

Question 23

media: deep

Answer 23

Test tube with media that goes straight across. You use a needle to push bacteria down under the surface to activate anaerobic enzymes

Question 24

media: buffer

Answer 24

Added to medias to counteract the effect of acids

Question 25

synthetic media

Answer 25

made of pure chemicals

Question 26

complex media

Answer 26

contain foods, peptones

Question 27

What is Agar

Answer 27

Polysaccharide from algae, jelly | Used in media to mountain moisture to prevent dehydrating and freezing at certain temps

Question 28

selective media

Answer 28

Allows the growth of 1 microorganism over the other | Examples are EMB, Pea agar and Maconkey

Question 29

What is an EMB

Answer 29

selective media, that allows gram - to grow over gram+

Question 30

What is a PEA agar

Answer 30

Comes with or without blood, selective for gram +

Question 31

Why is counting microbes important

Answer 31

It helps determine how bad food is or how intense an infection may be Ways to count include direct: streak plate, pour plate, spread plate, serial dilutions, filtration, MPN, chambers and culture counter indirect: spectrophotometer, metabolic

Question 32

What are colonies

Answer 32

Time mounds of bacteria that contain 100's of bacteria that create a colony. Have special characteristics Plate has to be streaked tp create the colonies

Question 33

What is a streak plate

Answer 33

When small amount of bacteria is placed on a plate Create 4 quadrants but bacteria is only aseptically applied once. IT is not a direct count, more of a ball park guess of number of colonies

Question 34

What is the pour plate method

Answer 34

Bacterial dilution 1.0-0.1 ml The disadvantage of this is that bacteria can be destroyed and appear different under than they do above. Hard to identify 1. inoculate an empty plate 2. Add melted agar 3. Swirl to mix 4. Colonies grow underneath(facultative anaerobe) or onto of the agar

Question 35

What is the spread plate method

Answer 35

Same as the put plate method except you spread out the organisms on the surface with beads and colonies grow only on the surface

Question 36

What are serial dilutions

Answer 36

Goal is 30-300 colonies on a plate, to do this dilutions need to be done 1:100= 1 ml added to the 9 ml of broth The number of colonies will get lower the more the inoculum is diluted but easier to count bacteria in those

Question 37

What is filtration

Answer 37

When filters are placed to trap bacteria flowingg in air or water The filters that trap bacteria are placed on Petri dish to get food to grow, they are then counted and identified

Question 38

What is MPN

Answer 38

Method that fives you a very wide range of possible number of microbes that can grow in combinations of test tubes containing nutrient agar 10ml= 5 bacteria 1 ml= 3 bacteria 0.1= 1 bacteria Gives us a number of positive tubes and most possible number of bacteria Not done often

Question 39

What is the petfroff houser chambers

Answer 39

A specified volume under a coverslip on top is a grid to count the number of bacteria The disadvantage is that it counts living and dead bacteria, and any bacteria with tails can swim underneath the surface and not be counted

Question 40

What is the Coulter counter

Answer 40

Is used if you don't want to plate out bacteria Fluids can pass through and instruments are used to count the number of bacteria. Is useful in research labs and hospitals when you want to know immediately the bacteria count Disadvantage is that other particles that aren't bacteria can be counted aswell

Question 41

What is a spectrophotometer

Answer 41

Indirect count Measures the % of light that passes through a solution and tells you the approximate amount of particles that may be in the solution It is important to dry and weigh so you can get an accurate number when it come to fungi bc they are masses of fibrous particles

Question 42

What is metabolic counting

Answer 42

indirect count Where you measure inout and output. You can take a guess of how many microbe may be there if you know how much food you fed and what kind of organisms it may be Can also count carbon dioxide and acids

Question 43

How do salts and sugars preserve food

Answer 43

They create a hypertonic enviroment

Question 44

What is facultative anaerobe on a graph

Answer 44

Has a with and without line, v shape facing north east

Question 45

In the bacterial growth curve, which phases are logarithmic

Answer 45

Log and death phase

Question 46

Most bacteria grow In what ph

Answer 46

7, neutral

Question 47

What is the generation time in bacteria

Answer 47

The time it takes for a cell to divide

Question 48

What phase are antibiotics effective

Answer 48

Log phase

Question 49

3 cells and ended with 192 cells, how many generations

Answer 49

6

Question 50

What do you call an organism that can live with or without salt

Answer 50

facultative halophile

Question 51

What do you call an organism killed by oxygen

Answer 51

obligate anaerobe