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BIO111: Microbiology > Chapter 4 > Flashcards

Chapter 4 Flashcards

(85 cards)

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0
Q

What is Asexual Reproduction called

A

Binary Fission

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1
Q

Microbial Growth

A

The growth of a population through an increase in the number of cells in a specific amount of time

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2
Q

Binary Fission steps

A
  1. Parent cell increases in size
  2. Chromosome is copied
  3. DNA attaches to cell membrane
  4. New cell walls form
  5. Cell divides into two new cells
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3
Q

Budding

A

Yeast and some bacteria species

a bud forms on parent cell

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4
Q

Growth curve

A

Distinct, sequential phases of growth in a lab with a closed system (agar, broth)

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5
Q

Steps of Growth Curve

A
  1. Lag Phase
  2. Exponential (Log) phase
  3. Stationary Phase
  4. Death phase
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6
Q

Lag Phase

A
  • preparation for cell division; no increase in population size
    Metabolic Activity
    -Enzyme and protein synthesis
    -Breakdown of substances in environment
    -Synthesis of new macromolecules and ribosomes
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7
Q

How long is lag phase?

A

Varies because of bacteria type and environment

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8
Q

Exponential (Log) Phase

A
  • Cell numbers increase exponentially (slowly at first then extremely rapid)
  • Cells are most virulent at this phase
  • Most sensitive to antimicrobial medications
  • Limited by nutrients, oxygen, waste accumulation, space
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9
Q

Generation time

A

Time it takes for one cell to divide into two cells (or population to double).
-10 minutes to 24 hours (average 30 minutes)

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10
Q

Formula for measuring population

A 
Nt = N0 x 2n
N0= original number of cells in a population
Nt= number of cells in a population at a given time
n= number of divisions in a given amount of time
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11
Q

Stationary Phase

A

Environmental conditions do not favor continues growth
-Death rate = division rate
Cells may produce survival structures (glycocalyx, endospores, cytoplasmic inclusions

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12
Q

Abcess

A

collection of pus surrounded by inflamed tissue

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13
Q

What is pus made of

A

WBCs, tissue debris, prtoeins and bacteria

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14
Q

Abscess

why formed and what happens

A

Body’s response to bacteria

Nutrients are limited so bacteria go to stationary phase

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15
Q

Are antimicrobials effective for abscesses?

A

No because bacteria is not dividing

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16
Q

Death phase

A

Cells begin to die out
Exponential death at a low rate
ATP reserves depleted
Prolonged decay: some cells survive by using nutrients of dead cells

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17
Q

Growth Phases in lab vs. nature

A

-Cultures pass through all growth phases in lab but not in nature.
- In nature nutrients enter cell’s environment at low concentrations.
therefore growth is continuous, steady but at a low rate. Limited by nutrients. Metabolic wastes are removed by other microbes

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18
Q

Nutrients r/t position in colony

growth on agar

A

Edges: lots of nutrients = exponential growth
Middle: limited nutrients = stationary growth
Center: depleted nutrients = death

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19
Q

Growth on agar

A

On solid media bacteria grows in colonies

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20
Q

Colony

A

a distinct mass of cells that originate from a single cell

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21
Q

Microbes can exist in many environments because they are…

A

small
easily dispersed
need only small quantities of nutrients
diverse in nutritional requirements

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22
Q

Environmental influences on Microbial Growth

A

moisture, temperature, pH, oxygen, solute concentration, hydrostatic pressure, radiation, nutrients

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23
Q

Moisture

influences on microbial growth

A
  • Bacteria use diffusion to get nutrients from the environment (so water is needed for diffusion to occur)
  • Preserving food through dehydration prevents bacteria from multiplying but may not kill bacteria
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24
Temperature | influences on microbial growth
-Microbial species have specific temperature ranges in which they can grow
25
Reasons why extreme heat or cold affects growth
very cold - proteins not denatures, microbes not killed just slowed very hot - proteins denatured, metabolism stops, cells destroyed
26
Optimum temperature
Usually a small range where organism has fastest rate of growth
27
Psychrophiles
cold loving 5-15 C Grow in polar and glacial regions
28
Psychrotrophs
"cold feeding" 20 - 30 C do not cause infection in humans responsible for spoiling of refrigerated and frozen food (Blood)
29
Mesophiles
middle loving 25 - 45 C Pathogens are mesophiles optimum temperature for human pathogens is around 37C
30
Normal body temp in C
37 C
31
Most refrigerators run what temp in C
4 C
32
Thermophiles
heat loving 45 - 70 C Found in natural hot springs, compost
33
Hyperthermophiles
extreme heat loving 70 C and higher usually Archaea hydrothermal vents in ocean
34
pH | influences on microbial growth
pH of external environment - internal pH is neutral
35
Acidophiles
optimal pH is below 5.5 | example: H. Pylori
36
Neutrophiles
optimal pH 6-8 | Human pathogenic bacteria optimum pH is 7.3
37
Alkaliphiles
optimal pH above 8.5 (very small group of bacteria | ex. alkaline lakes and soils
38
Bleach
pH of 10 | kills most bacteria
39
``` Hydrostatic pressure (influences on microbial growth) ```
- pressure exerted by standing water - Most bacteria killed by high pressure (autoclave) - Some extreme microbes need high pressure to keep enzymes from denaturing
40
Radiation | influences on microbial growth
Can damage or kill microbes | 3 types: Ionizing, UV, microwave
41
Ionizing radiation
removes electrons - destroys DNA, damages membranes ex. Xrays and Gamma rays Gram + can survive longer than Gram -
42
Uv radiation
``` destroys DNA (mutations) some bacteria have repair enzymes to correct mutations ```
43
Microwave radiation
kills bacteria with heat only
44
Harmful oxygen-containing molecules
Superoxide ion (o2-) Peroxides(H2O2) Damage living tissue (especially membranes and can kill cells -> aging
45
Antioxidants
Enzymes present in organisms to detoxify harmful oxygen containing molecules
46
Examples of antioxidants
``` Superoxide dismutase (SOD) Catalase ```
47
Superoxide dismutase
converts O2- to O2 + H2O2
48
Catalase
converts H2O2to O2 and H2O
49
Obligate Aerobes
- Have SOD and catalase - must have O2 for metabolism (aerobic respiration) and growth - ex. most fungi and protists, some bacteria (Bacillus, Pseudomonas)
50
Facultative Anaerobes
- Usually have SOD and catalase - "flexible" - can survive with or without oxygen - Grow best with oxygen (aerobic respiration - Ex. Ecoli, Staphylococcus and Saccharomyces(yeast)
51
Microaerophiles
- Only need small amounts of SOD and catalase - Need small concentrations of O2( 2-10%) for aerobic respiration - Large amounts of oxygen are inhibitory - Found in mucous linings of hollow organs - Ex. H. Pylori
52
Obligate Anaerobes
- Usually lack both SOD and catalase - Cannot grown if O2 is present - No aerobic respiration - Found in deep mud, lakes, oceans, inside animal bodies - Ex. Clostridium
53
Aerotolerant Anaerobes
- May have SOD, but not catalase - Indifferent to oxygen - Do not use oxygen (OBLIGATE FERMENTERS) - Ex. Streptococcus pyogenes
54
How do bacteria try to maintain a hypotonic environment?
They will pump in K+ of produce extra amino acids
55
Halotolerant
- can tolerate moderate concentrations of salt - up to 10% NaCl ex. staph on the skin
56
Halophiles
- REQUIRE a high level of NaCl - Marine microbes - Extreme halophiles are Archaea living salt lakes
57
Osmophiles
grow in high sugar concentrations
58
Element reminds
C. Hopkins CaFe Mg | C. Hopkins Cafe Mighty good
59
Carbon
energy source (glucose) and building blocks
60
Nitrogen
amino acids, nucleotides - some can synthesize all 20 amino acids - others need amino acids added to culture medium
61
Sulfer
amino acids, coenzymes
62
Phosphorus
ATP, phospholipids, nucleotides
63
Vitamins
- organic substance required by an organism, usually a coenzyme - some bacteria make own vitamins - others need vitamins added to culture medium - microbes in human intestine make Vitamin K and some B vitamins = mutualistic symbiosis
64
Other elements are often...
cofactors
65
Media
liquid or solid material used to grow microbes
66
Agar
solidifies culture media at 1.5% concentration - complex polysaccharide, extracted from seaweed - melts at 100C and solidifies at 45C - first used by Koch (Mrs. Hess) - not degraded by microbes
67
Sterilizing agar
in autoclave | 121 C for at least 15 minutes at 15 psi of steam
68
Liquid Media (broth)
good for growing large numbers of bacteria in a short time, contains low concentrations of agar (0.5%) for motility test
69
Defined (synthetic) media
made of exact amounts of pure chemicals
70
Complex media
- made of some ingredients with variable chemical composition - can vary from batch to batch - extracts from beef, yeast, blood... - example nutrient agar
71
Selective media
- encourages the growth of some microbes and suppresses the growth of others - for isolation of microbes
72
Differential Media
- contains substances that certain microbes can change in a recognizable way - observable changes in media due to biochemical reaction from microbe - ex. color or pH change
73
Indirect measurements
measure property of the mass of cells and then estimate the number of microbes
74
Direct measurement
determine the total number of cells, includes living and/or dead cells, more accurate measurements of numbers of microbes
75
Turbidity
- cloudiness as evidence of growth - can use spectrophotometer - measures biomass not number of cells - cannot detect minor concentrations
76
Metabolic Activity
1. Rate of metabolic products that a culture produces: gases, acids 2. Rate of utilization of a substrate: Oxygen, glucose, ATP 3. Rate of reduction of certain dyes: methylene blue becomes colorless when reduced
77
2 types of Indirect measurement
Turbidity | Metabolic Activity
78
Direct cell counts
1. Direct Microscope count | 2. Coulter Counter
79
Direct microscope count
special glass slide with light compound microscope
80
Coulter Counter
- electronic, cells pass through a narrow channel | - rapid, accurate
81
Viable cell count
1. Standard plate count | 2. Filtration
82
Standard plate count
count colonies against a grid - Quebec colony counter - use serial dilutions to decrease cell numbers before counting
83
Filtration | viable cell count technique
fine, sterile filter collects microbes, then placed on agar plate, count colonies, used to concentrate samples
84
Countable plate has how many cells
30 -300 more - too many cells produce too many colonies to count less - not enough colonies for a valid count

BIO111: Microbiology (12 decks)

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