Chapter 6 Vocab Part 2

Question 1

Culture Medium

Answer 1

nutrient material prepared for growth of microorganisms in a laboratory

Question 2

Culture

Answer 2

microorganisms that grow and multiply in a container of culture medium

Question 3

Inoculum

Answer 3

microbes that are introduced into a culture medium to initiate growth

Question 4

Sterile

Answer 4

containing no living microorganisms

Question 5

Chemically Defined Medium

Answer 5

culture medium in which the exact chemical composition is known

Question 6

Complex Media

Answer 6

made of nutrients including extracts from yeast, meat, plants, or digests of proteins from these sources

Question 7

Nutrient Agar

Answer 7

nutrient broth containing agar

Question 8

Nutrient Broth

Answer 8

complex medium in liquid form

Question 9

Reducing Media

Answer 9

contain ingredients that chemically combine with dissolved oxygen and deplete that oxygen in the culture medium

Question 10

Capnophiles

Answer 10

microorganism that grows best at relatively high CO2 concentrations

Question 11

Selective Media

Answer 11

culture medium designed to suppress the growth of unwanted microorganisms and encourage the growth of desired ones

Question 12

Differential Media

Answer 12

makes it easier to distinguish colonies of the desired organism

Question 13

Enrichment Culture

Answer 13

culture medium used for preliminary isolation that favors the growth of a particular microorganism

Question 14

Colony

Answer 14

visible mass of microbial cells arising from one cell or from a group of the same microbes

Question 15

Streak Plate Method

Answer 15

method of isolating a culture by spreading microorganisms over the surface of a solid culture medium

Question 16

Deep-Freezing

Answer 16

process in which a pure culture of microbes is placed in a suspending liquid and quick-frozen at temperatures ranging from -50 degrees Celsius to -95 degrees Celsius

Question 17

Lyophilization

Answer 17

a suspension of microbes is quickly frozen at temperatures ranging form -54 degrees Celsius to -72 degrees Celsius

Question 18

Binary Fission

Answer 18

cell reproduction by division into two daughter cells

Question 19

Budding

Answer 19

asexual reproduction beginning as a protuberance from the parent cell that grows to become a daughter cell

Question 20

Generation Time

Answer 20

the time required for a cell to divide

Question 21

Bacterial Growth Curve

Answer 21

a graph of a bacterial population over time

Question 22

Lag Phase

Answer 22

a period of little or no cell division

Question 23

Log Phase

Answer 23

period of growth when cellular reproduction is most active

Question 24

Stationary Phase

Answer 24

period of equilibrium, the number of microbial deaths balances the number of new cells and the population stabilizes

Question 25

Death Phase

Answer 25

the number of deaths eventually exceeds the number of new cells formed, continues until the population is diminished to a tiny fraction of the number of cells in previous phase or until the population dies out entirely; decreases in bacterial population

Question 26

Plate Count

Answer 26

method of determining the number of bacteria in a sample by counting the number of colony-forming units on a sold culture medium

Question 27

Colony-Forming Units

Answer 27

visible bacterial colonies on solid media

Question 28

Serial Dilution

Answer 28

to ensure that some colony counts will be within the range, the original inoculums is diluted several times with this process

Question 29

Pour Plate Method

Answer 29

method of inoculating a solid nutrient medium by mixing bacteria in the melted medium and pouring the medium in to a Petri dish to solidify

Question 30

Spread Plate Method

Answer 30

This method positions all the colonies on the surface and avoids contact between the cells and melted agar

Question 31

Filtration

Answer 31

water is passed through a thin membrane filter whose pores are too small to allow bacteria to pass, thus the bacteria are filtered out and retained on the surface of the filter

Question 32

Most Probable Number Method

Answer 32

a statistical determination of the number of coliforms per 100 ml of water or 100 g of food

Question 33

Direct Microscopic Count

Answer 33

a measure volume of a bacterial suspension is placed within a defined area on a microscope slide; often used to count the number of bacteria in milk

Question 34

Turbidity

Answer 34

a practical way of monitoring bacteria growth