Ch.6

Question 1

Microbial Growth

Answer 1

increase of number of cells, not size

Question 2

Physical requirements for microbe growth

Answer 2

temp, ph, osmotic pressure

Question 3

Chemical requirements

Answer 3

carbon, nitrogen, sulfur, phosphorus , trace elements, oxygen organic growth factor

Question 4

Psychrophiles

Answer 4

cold loving microbes 20-30 C

Question 5

Mesophiles

Answer 5

moderate temperature microbes (grow at human temp)

Question 6

Thermophiles

Answer 6

heat loving microbes

Question 7

Osmotic pressure

Answer 7

Hypertonic environments or increase in salt and sugar cause plasmolysis
(water flows out)

Question 8

Extreme/obligate halophiles

Answer 8

require high osmotic pressure

Question 9

Chemical requirements

Answer 9

carbon- energy+ structure Nitrogen- amino acids + proteins Sulfur- amino acids + proteins, Phosphorus- DNA+RNA+ATP+Membrane

Question 10

Toxic oxygens

Answer 10

Singlet oxygen, molecular oxygen boosted to a higher-energy state. Superoxide free radicals , Peroxide anion, Hydroxyl radical

Question 11

Organic Growth Factors

Answer 11

Organic compounds obtained from the environment like Vitamins, amino acids, purines, and pyrimidines

Question 12

Vitamins, amino acids, purines, and pyrimidines

Answer 12

Microbial Communities, form slime or hydrogels. Bacteria are attracted via quorum sensing.
Share nutrients and are sheltered from harmful factors

Question 13

Culture medium

Answer 13

something prepared for the purpose of growing microbes.

Question 14

Sterile

Answer 14

No living microbes

Question 15

Inoculum

Answer 15

introduction of microbes into medium

Question 16

Culture

Answer 16

microbes growing in/on culture medium

Question 17

Agar

Answer 17

A culture media with complex polysaccharide, used for petri plates, slants and deeps. Not metabolized by microbes

Question 18

Chemically defined media

Answer 18

exact chemical composition is known

Question 19

Complex media

Answer 19

extracts and digests of yeasts, meat or plants, May be a nutrient broth or nutrient agar and must have a source for C,N, S,P and cofactors

Question 20

anaerobic bacteria cultures

Answer 20

could be killed by oxygen, so they use a special reducing media athat has chemicals that combine with dissolved oxygen and depleted the oxygen in the culture media

Question 21

Capnophile

Answer 21

microbes that require high COv2 conditions

COv2 packet or candle jar

Question 22

Differential Media

Answer 22

make it easy to distinguish colonies of different microbes

Salt concentration of 2% or more generally preserve, by making the cell unable to reproduce

Question 23

Selective Media

Answer 23

suppress unwanted microbes and encourage certain microbes

Question 24

Enrichment Culture

Answer 24

encourages growth of a certain microbe, does not necessarily suppress another

Question 25

colony

Answer 25

encourages growth of a certain microbe, does not necessarily suppress another

Question 26

BSL 1-4

Answer 26

1- no special precautions. 2 lab coat, gloves, eye protection. 3 biosafety cabinets to prevent airborne transmission. 4- sealed, negative pressure, exhaust air is filtered twice

Question 27

Binary Fission

Answer 27

main method of prokaryote reproduction where they split apart

Question 28

Budding

Answer 28

bacteria form a bud that enlarges to the size of a parent cell, then separates (think a stem away from tree)

Question 29

Conidiospores

Answer 29

small usually single-celled asexual reproductive body , made by pLANTS fungi and some bacteria.

Question 30

Phases of growth

Answer 30

Lag phase intense acidity preparing for population growth. Log phase- logarithmic or exponential increase in population. Stationary phase- period, of equilibrium, microbial death, balance production of new cells . Death phase- population is decreasing at a log rate.

Question 31

Plate count

Answer 31

most common method of measuring bacteria population, measures viable cells, but takes 24+ hours for visible colonies to form Plates assumes that the bacteria grows and forms a single colony and known as colony forming units (CFU) They are counted by colonies that have 25-250 colonies

Question 32

Pour plate method

Answer 32

a plate count of where bacterial dilution is put onto a empty plate and then melted nutrient agar is the poured and swirled into it. The colonies grow on top and in the solidified agar. But the melts agar maybe too hot for some bacteria.

Question 33

Spread plate method

Answer 33

plate count where solid medium is already on a dish and bacterial dilution is spread on the medium, then colonies grow only on the surface

Question 34

Filtration method

Answer 34

where 100 ml of water is passed through a then membrane where bacteria is too small to pass so it stays on there and is then put on a dish

Question 35

MPN Most probable number

Answer 35

based on the fact that the greater the number of bacteria in a sample, the more dilution is needed to reduce the density to the point at which no bacteria are left to grow in the tubes in a dilution series. They get a series of tubes and put certain dilutions in them, the less diluted the less amount of tubes are postivee They then use a statistical table to guestimate with 95% confidence

Question 36

Generation rate

Answer 36

The rate of exponential growth of a bacterial culture is expressed as generation time, also the doubling time of the bacterial population

Question 37

Direct microscopic count

Answer 37

a measured volume of bacteria suspension is placed within a defined area on a microscope slide. Needs high number, bacteria may be dead or alive, and problems if motile. Uses a petroff-hausser cell counter that uses a grid with squares etched into it. Number of bacteria

Question 38

Turbidity

Answer 38

a sample is taken from a broth and measure the absorbance of light in a spectrophotometer . Indirect method

Question 39

Metabolic activity

Answer 39

a product is produce and that is proportional to how ever many bacteria is present

Question 40

Dry weight

Answer 40

when it is weighed after being dry