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Microbio - LSCI 230 > Chapter 5 - Microbial Growth > Flashcards

Chapter 5 - Microbial Growth Flashcards

1
Q

nutrients in which metabolism is simple

A

N, S, P

only slight modifications are needed before incorporating into cellular material

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2
Q

sources in which many transformations must be done during metabolism

A

carbon and energy

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3
Q

what is a macronutrient

A

required in large amounts

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4
Q

examples of macronutrients

A

Carbon, Nitrogen, Hydrogen, Oxygen, Phosphate, Sulfur, Potassium, Magnesium, Calcium, Sodium

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5
Q

what is a muicronutrient

A

required in trace amounts

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6
Q

examples of micronutrients

A

iron and trace metals

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7
Q

what is a growth factor

A

molecules that a microorganism needs for growth but cant synthesize by itself. can be byproduct or waste of another microbe

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8
Q

examples of growth factors

A

vitamins, amino acids, purines, pyrimidines, other organic molecules

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9
Q

how to most prokaryotes multiply

A

binary fission

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10
Q

what is binary fission

A

cells grow in size until it forms a partition that constricts the cell into 2 daughter cells

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11
Q

true or false: daughter cells are able to exist independently immediately after creation

A

true

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12
Q

what do daughter cells receive from the mother cell

A

daughter cell receives one copy of the chromosome, ribosomes, macromolecules, monomers, and other necessary molecules to exist independently

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13
Q

what must happen in order for cell division to occur

A

destroying of the cell wall and peptidoglycan to change the size of the cell

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14
Q

what exports NAM and NAG peptidoglycan subunits across the cytoplasmic membrane

A

bactoprenol

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15
Q

2 things cell division requires

A
  1. synthesis of new cell wall material

2. destruction of cell wall material by autolysins

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16
Q

when does bactoprenol fuction

A

during synthesis of new cell wall

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17
Q

what is FTsZ ring

A

the division ring

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18
Q

what are autolysins

A

bacteriolytic enzymes that digest and synthesize the peptidoglycan of the cell wall

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19
Q

how do autolysins function

A

they create gaps in the peptidoglycan at the division ring to allow rearrangement and synthesis of a new cell wall

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20
Q

what is a wall band

A

scar between old and new peptidoglycan

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21
Q

true or false: the mechanism for division of archaea with a cell wall is very different from that of bacteria

A

false

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22
Q

how is macconkey selective

A

it contains bile salts that inhibit G+ (ALLOW G-)

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23
Q

what does macconkey differentiate between and by what colors

A

lactose fermenters - pink

lactose non-fermenters - colorless

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24
Q

what is the pathway of lactose fermentation and what effect does it have on the medium

A

lactose to glucose and galactose
glucose to glycolytic pathway
pyruvate to fermentation
lactic acid created, thus lowering the pH

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25
Q

does E. Coli create pink or transparent colonies in a macconkey

A

dark pink

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26
Q

how is mannitol salt selective and what about it allows this

A

inhibits G-
allows G+
high NaCl concentration

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27
Q

what organism is mannitol salt used to detect

A

staphylococcus

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28
Q

+ v - on mannitol salt

A

+: mannitol fermenters yellow

-: not mannitol fermenter, pink

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29
Q

staphylococcus aureus is manitol …

A

positive

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30
Q

staphylococcus epidermidis is manitol…

A

negative

31
Q

reasons to measure presence, growth, and identifications of microorganisms

A
  1. evaluate contamination of food, water, etc
  2. ensure microbes are innoculated during processing of beer, wine, yogurt, cheese, etc.
  3. evaluate antimicrobial agent efficiency
  4. study microbe populations from different ecosystems
  5. measure effects of mutations of genes
32
Q

what type of medium is required for viable counts

A

permissive growth medium

33
Q

in what range are there reliable results for viable counts

A

between 30 and 300 colonies

34
Q

what do you measure during viable counts and why

A

colony forming units because theoretically each colony is made from 1 bacteria, so the number of colonies measures how many bacteria is present

35
Q

equation for colony forming units

A

(# of colonies) / ((dilution plated)(volume plated))

36
Q

what needs to be done to get a viable count of bacterial cultures with a high number of cells

A

serial dilution

37
Q

what plate in the serial dilution do you base your results off of?

A

the one in the 30-300 range; only reliable one

38
Q

what do you do in a microscopic count

A

count all cells (dead or alive) per specific volume under a microscope

39
Q

how do you tell the difference between dead and living cells in a microscopic count

A

viability stain
green = alive
red = dead

40
Q

pros of microscopic counts

A

fast
cheap
motility can be prevented by increasing viscosity
good when you need to count only 1 sample

41
Q

cons of microscopic counts

A

difficult to see small cells (bacteria)
not good when you need to count more than 1 sample
harder to count motile cells

42
Q

concept of volume in microscopic counts

A

height/distance of coverslip from sample, width and length of gridlines allows you to calculate volume. count the number of cells within this volume

43
Q

what is flow cytometry

A

automated cell counter; puts cells in a straight line and uses a laser to detect flourescent dyes, count, and LABEL cells

44
Q

what information does flow cytometry provide

A

texture, size, shape, labeling of cells

45
Q

is flow cytometry better at counting small or big cells

A

big

46
Q

does flow cytometry count cells that alive, dead, or both

A

it differentiates between dead and alive cells

47
Q

what is the turbidimetric method

A

measures the contribution of alive and dead cells to turbidity. a spectrophotometer is used to measure how much light the solution blocks

48
Q

what is the relationship between cell density and turbidity

A

higher density = more opaque/turbid

49
Q

does the turbidimetric measure dead or alive cells>

A

both

50
Q

what alters the behavior of cells and thus turbidity

A

clumping and attachment to surfaces

51
Q

what kind of graph can be created with the turbidimetric method

A

optical density v time

52
Q

what properties affect optical density

A

size, shape, composition, cell inclusion, etc

53
Q

what does the OD v time curve tell us

A

the relationship between OD and cell number for different organisms

54
Q

true or false: turbidity accurately detects the number of cells

A

false; it is an approximation since it tells you dead and alive cells and many properties may affect it

55
Q

what is generation time

A

time needed for the population to double

56
Q

what does generation time depend on

A

growth medium and environmental conditions

57
Q

equation for exponential growth of microorganisms and when does this occur

A 
N= (N0)(2^n)
N = number of cells
N0 = initial number of cells
n = number of generation
this occurs when the conditions are optimal and the population doubles at a constant rate
58
Q

equation for generation time

A

g=t/n
g= generation time
t = time
n = number of generation

59
Q

look at generation time and growth phase graphs and be able to interpret them

A

okie mims

60
Q

what are the 3 phases of growth that occur in a batch culture

A
  1. lag phase
  2. exponential growth phase
  3. stationary phase
  4. death phase
61
Q

what is happening in the lag phase

A

the bacteria is placed in the broth and adjusting to its environment. only turbidity line occurs in this region. slow growth

62
Q

what is happening in the exponential growth phase

A

the viable count starts and both viable count and turbidity exponentially increase - doubling at a constant rate

63
Q

what is happening in the stationary phase

A 
limiting nutrients are depleted/accumlation of waste inhibits growth
growth stops (plateau)
no net increase in cell number
cells are metabolically active
survival mechanisms activated
64
Q

which plataeus first: turbidity or viable count

A

turbidity

65
Q

what occurs in the death phase

A

exponential death

66
Q

true or false: batch cultures are continually being affected by the metabolic activities of the growing microorganism

A

true. ex. depletion of nutrients and generation of toxic waste

67
Q

is the batch culture an open or closed system

A

closed

68
Q

what about batch cultures is different from the real environment

A

no turnover of nutrients - most natural environments are open systems

69
Q

what characteristics are present in open systems

A
  1. constant supply of nutrients
  2. diffusion of waste
  3. competition
  4. predation
  5. changing environmental conditions
70
Q

how is equilibrium defined for environmental systems

A

division rate equals death rate

71
Q

what is the main factor for environmental equilibrium

A

the concentration of a limiting growth factor

72
Q

what is a chemostat used for and how

A

keep microorganisms in a constant growth rate over a long period of time by providing fresh broth (supply of nutrients) and removing overflow (waste and organisms) at a constant rate

73
Q

what contributes to the death rate of microorganisms in the environment

A

sickness leading to death, predation (eaten by something else), or being taken away by the environment

Microbio - LSCI 230 (1 decks)

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