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From Flashcardlet > Microbio Exam 1 > Flashcards

Microbio Exam 1 Flashcards

1
Q

Characteristics of Microorganisms.

A
  • Inhabit every environment that supports life

- Single-celled, complex structures, multicellular

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2
Q

How long have microorganisms been on this planet?

A

3.8 Billion years.

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3
Q

What are the tools used in microbiology?

A
  • Microscopy
  • Culture
  • Medium
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4
Q

What do ALL cells have in common?

A
  • Cytoplasmic membrane
  • Cytoplasm
  • Ribosomes
  • DNA
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5
Q

Characteristics of Prokaryote.

A
  • Single-cellular chromosome that aggregate into nucleoid region
  • Contain plasmids
  • Small, compact
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6
Q

Characteristics of Eukaryote.

A
  • Linear chromosome with nucleus

- Larger, more DNA than Prokaryotes

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7
Q

What are positive impacts of microorganisms in food?

A
  • Improve food safety

- Preservation

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8
Q

What are negative impacts of microorganisms in food?

A
  • Food spoilage
  • FBI
  • Influences harvest and storage
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9
Q

Which organisms are Prokaryotic?

A
  • Bacterium

- Archaea

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10
Q

What type of organisms are eukaryotic?

A
  • Fungi
  • Animals
  • Algae
  • Protozoa
  • Plants
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11
Q

What are the 3 domains and their cell types?

A
  • Bacterium (prokaryotic)
  • Archaea (prokaryotic)
  • Eukarya (eukaryotic)
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12
Q

Approximately how old is the Earth?

A

4.6 billion y/o.

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13
Q

What was the makeup of the early atmosphere?

A
  • Anoxic

- Anoxygenic phototrophs

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14
Q

What made the atmosphere oxygenic?

A

Presence of cyanobacteria, which are able to produce oxygen.

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15
Q

What is the relationship of the 3 domains?

A

All descendants of Last Universal Common Ancestor (LUCA).

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16
Q

What is the role of microorganisms in the gut?

A

Digestion of carbohydrates.

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17
Q

How can microorganisms benefit humans?

A
  • Valuable byproducts
  • Energy generation
  • Environmental clean up
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18
Q

How can microorganisms harm humans?

A
  • Agents of disease

- Food and agricultural risks

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19
Q

What was Robert Hooke’s achievement?

A
  • First to describe microbes

- Illustrated the fruiting structures of molds

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20
Q

What was Antoni van Leeuwenhoek’s achievement?

A

First to describe bacteria.

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21
Q

What were Louis Pasteur’s discoveries?

A
  • Living organisms discriminate between optical isomers
  • Alcoholic fermentation was a biologically (not just chemically) mediated process
  • Swan-neck flask disproved spontaneous generation (led to food preservation and sterilization methods)
  • Developed vaccinations for anthrax, fowl cholera, and rabies
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22
Q

Which 4 criteria were established by Koch’s postulates to identify causative agents of a particular disease?

A
  • Microbe must be present in all cases of the disease
  • Microbe can be isolated from diseased host and grown in pure culture
  • Microbe from pure culture must cause the disease when inoculated into a healthy animal
  • Microbe must be re-isolated from the new host and shown to be the same as the originally inoculated pathogen
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23
Q

What was Sergei Winogradsky’s major contribution?

A

Concept of chemolithotrophy.

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24
Q

What were other contributions by Sergei Winogradsky?

A
  • Biogeochemical transformations

- First to demonstrate nitrogen fixation

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25
Q

What was Frederick Griffith’s major contribution?

A

He discovered the “transforming principle” in the pneumococcus bacteria.

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26
Q

How are specimens visualized in a compound light microscope?

A

Differences in contrast (density) between specimen and surroundings.

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27
Q

What is the general purpose of staining?

A

To improve contrast.

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28
Q

What is the use for differential stains?

A

Provides contrast between different types of cells.

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29
Q

What is the difference between gram-positive and gram-negative cells?

A
  • (+) = purple-violet

- (-) = pink

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30
Q

What is the main difference between TEM and SEM?

A

SEM views the surface of the structure, whereas TEM is much more detailed (greater resolution).

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31
Q

How was rRNA used by Carl Woese to reconstruct the tree of life?

A
  • rRNA sequences could be used to infer evolutionary relationships
  • Named new group Archaea
  • Relationships deduced by comparing genetic information in different specimens
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32
Q

What are the components of bacterial plasma membrane?

A
  • Phospholipid bilayer (6-8nm)
  • Integral embedded protein
  • Peripheral embedded protein
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33
Q

What are the 2 differences between Archaeal and Bacterial membranes?

A
  • Archaeal have ether linkages, Bacterial has Ester

- Archaeal lipids have isoprenes, Bacterial has fatty acids

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34
Q

Characteristics of a gram-negative cell wall.

A
  • Two membranes surrounding thin peptidoglycan

- Outer membrane contains LPS and porin proteins

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35
Q

Characteristics of a gram-positive cell wall.

A
  • One thick membrane with peptidoglycan
  • Teichoic acids
  • Lipoteichoic acids
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36
Q

What is the structure of Peptidoglycan?

A
  • Rigid layer
  • Alternating NAG and NAM
  • Amino acid (peptide) inter-bridges
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37
Q

What is the effect of lysozymes on Peptidoglycan?

A
  • Destroy peptidoglycan

- Cleave glycosidic bond between sugars

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38
Q

What is the effect of lipid A in humans?

A

Too much, acts as endotoxin.

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39
Q

Which genera of cells lack a cell wall?

A
  • Mycoplasmas

- Thermoplasma

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40
Q

How do Mycoplasmas and Thermoplasma withstand osmotic pressure?

A

They utilize stronger cytoplasmic membranes like sterols or lipoglycans.

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41
Q

Name structures of archaeal cell walls

A
  • Pseudomurein

- S-layers

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42
Q

Characteristics of Pseudomurein.

A
  • Composed of NAG and NAM acid
  • B-1,3 glycosidic bonds
  • All amino acids are L-stereoisomer
  • Cannot be destroyed by lysozymes and penicillin
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43
Q

Characteristics of S-layers.

A
  • Most common cell wall type
  • Consist of protein or glycoprotein
  • Paracrystalline structure
  • Fortify cell-wall, usually polysaccharides
  • Produced in times of need
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44
Q

Structure of Capsules and Slime Layers.

A
  • Polysaccharide layers

- May be thin, thick, rigid or flexible

45
Q

Characteristics of Capsules.

A
  • If tightly attached, tight matrix

- Visible if treated with India Ink

46
Q

Characteristics of Slime Layers.

A
  • Loosely attached
  • Easily deformed
  • Involved in biofilms
47
Q

What are the functions of capsules and slime layers?

A
  • Assist in attachment to surfaces
  • Development and maintenance of biofilms
  • Prevent dehydration/dessication
  • Virulence factors: protect against phagocytosis
48
Q

Structure and function of Fimbriae.

A
  • Protein structure
  • 2-10 nm wide
  • Enable organisms to stick to surfaces or form pellicles
49
Q

Structure and function of Pili.

A
  • Protein structure
  • 2-10 nm wide
  • Typically longer and fewer
50
Q

Function of Conjugative Pili.

A

Facilitate genetic exchange between cells.

51
Q

Function of Type IV Pili.

A
  • Adhere to host tissues

- Support twitching motility

52
Q

What are cell inclusions surrounded by?

A

Thin membranes.

53
Q

What if the function of a Cell Inclusion?

A
  • Energy reserve
  • Carbon reservoirs
  • Reduce osmotic stress
54
Q

What are the layers of endospores (from outermost to innermost)?

A
  • Exosporium
  • Spore coats
  • Cortex
  • Core
55
Q

What is the function of an Endospore?

A

Ensure cell survival.

56
Q

Which two genera can you commonly find endospores?

A
  • Bacillus

- Clostridium

57
Q

What occurs during Sporulation?

A

Vegetative cell converted to non-growing, heat-resistant, light-refractive structure.

58
Q

What occurs during Germination?

A

Re-emergence under favorable conditions often triggered by presence of water.

59
Q

What are the 3 parts of a flagella?

A
  • Basal body
  • Hook
  • Filament
60
Q

What are the 4 arrangements of flagella?

A
  • Polar
  • Lophotrichous
  • Amphitrichous
  • Peritrichous
61
Q

Describe the “run” behavior during chemotaxis.

A
  • Smooth forward motion

- Flagellar motor rotates counter-clockwise

62
Q

Describe the “tumble” behavior during chemotaxis.

A
  • Stops and jiggles
  • Flagellar motor rotates clockwise
  • Flagellar bundle comes apart
63
Q

What are all the organelles in a Eukaryotic cell?

A
  • Membrane-enclosed nucleus
  • Mitochondria
  • Microtubules
  • Microfilaments
  • Lysosomes
  • Endoplasmic reticulum
  • Golgi complex
64
Q

Structure of the Nucleus.

A
  • Contains chromosomes
  • Histones surround DNA
  • Enclosed by 2 membranes that interact with nucleoplasm (inner membrane) and cytoplasm (outer membrane)
  • Nucleolus
65
Q

What is the main difference between mitosis and meiosis?

A
  • Mitosis produces 2 diploid daughter cells

- Meiosis produces 4 haploid gametes

66
Q

What is the Endosymbiotic Hypothesis?

A

Mitochondria and chloroplasts descended from respiratory and phototrophic bacterial cells, respectively, associating with non-phototrophic eukaryal hosts.

67
Q

What is the evidence behind the Endosymbiotic Theory?

A

Mitochondria, hydrogenosomes, and chloroplasts contain circular DNA genomes and ribosomes.

68
Q

What are the reproductive strategies of eukaryotes?

A
  • Asexual and sexual

- Haploid and diploid

69
Q

What are the reproductive strategies of bacteria and archaea?

A
  • Asexual - Binary fission, budding, filamentous
  • Haploid only
  • Must replicate and segregate the genome prior to division
70
Q

What is the difference between Binary Fission and Budding?

A
  • Binary Fission is division into two equal cells

- Budding is the unequal division of a cell

71
Q

What are the steps in Binary Fission?

A
  • Cell enlarges in volume
  • Septum grows inwards as chromosomes move toward opposite ends of cell
  • Septum completely synthesizes making 2 cell chambers
  • At this point daughter cells are divided, some parts may remain to create other arrangements
72
Q

What is the process of biofilm formation?

A
  • Planktonic cells attach to a conditioned surface

- Secretion of extracellular polymeric substance (EPS)

73
Q

What are the benefits of biofilms to its occupants?

A

Protection from:

  • UV lights
  • Antibiotics
  • Antimicrobials
74
Q

What are the health risks of biofilm?

A
  • Lead to illness from medical devices/implants

- Contamination of a drinking water system

75
Q

How would a graph look if bacterial cell growth were to be graphed arithmetically?

A

Slow, then sudden spike upwards as time increases.

76
Q

How would a graph look if bacterial cell growth were to be graphed logarithmically?

A

A steady increasing line (diagonally).

77
Q

What are the stages of bacterial growth in order?

A
  • Lag phase
  • Exponential phase
  • Stationary phase
  • Death phase
78
Q

What occurs during the lag phase of bacterial growth?

A
  • Interval between inoculation and beginning of growth

- Enzymes and metabolites created before growth can begin

79
Q

What occurs during the exponential (Log) phase of bacterial growth?

A
  • Maximum growth rate observed

- Cells typically in healthiest state

80
Q

What occurs during the stationary phase of bacterial growth?

A
  • Growth rate = 0
  • Essential nutrient is used
  • Waste can accumulate
  • Metabolism slows down
  • Cells grow, some die (balance)
81
Q

What occurs during the death phase of bacterial growth?

A
  • Exponential rate
  • Slower than exponential growth
  • Viable cells remain for months or years
82
Q

What is Defined Media?

A

Exact chemical composition known.

83
Q

What is Complex Media?

A

Made of digests of microbial animal or plant products (yeast/meat extracts).

84
Q

What is Enriched Media?

A
  • Contains complex media + highly nutritious mats

- Used to culture nutritionally demanding microbes

85
Q

What is Selective Media?

A

Compounds inhibit growth of some microbes, but not others.

86
Q

What is Differential Media?

A

Contains indicator used to detect certain metabolic reactions.

87
Q

Why is Agar important?

A

Most microorganisms cannot degrade it.

88
Q

What are the 3 ways to measure growth?

A
  • Direct cell counts
  • Viable plate counts
  • Turbidity measurements
89
Q

What are the advantages of turbidimetric measurements?

A
  • Easy to do
  • Do not disturb or destroy sample
  • Same sample can be checked repeatedly
90
Q

What are the disadvantages of turbidimetric measurements?

A

May result in inaccurate counts due to clumps or biofilm liquids.

91
Q

What allows for cells to tolerate colder temperatures?

A
  • More a-helices than b-sheets
  • More poler, fewer hydrophobic amino acids
  • Cryoprotectants (prevent freezing)
  • Exopolysaccharide cell surface slime
  • Cold shock proteins
92
Q

What allows for cells to tolerate hotter temperatures?

A
  • Amino acid substitutions for more heat-tolerant folds
  • More ionic bonds
  • Hydrophobic interior
  • Produce solutes to help stabilize proteins
93
Q

which organisms would fall under realm of study

A

viruses protists, fungi (yeasts and molds), bacteria

94
Q

add chemical stimulant for runs and tumbles

A

see more runs and fewer tumbles (picking up environment, trying to get molecules to find receptors)

95
Q

When would you use a log curve and arithmetic curve?

A
  • Log = Extrapolate

- Arithmetic = Specific number

96
Q

What are the effects of low and high pH on cells?

A
  • Denaturation

- Charged molecules disrupt cell wall and kill structure

97
Q

What are the 3 organisms that can tolerate high salt concentrations?

A
  • Halophile
  • Halotolerant
  • Extreme halophiles
98
Q

How do organisms tolerate high salt environments?

A

Utilizing compatible solutes to maintain positive water balance.

99
Q

What kind of media is used to grow anaerobic organisms?

A

Reducing media.

100
Q

What is the role of reducing agents in anaerobic organisms?

A

They are used to reduce the amount of oxygen present in culture.

101
Q

Why is oxygen toxic?

A

While the molecule itself is not toxic, it yields toxic byproducts such as:

  • Superoxide anion
  • Hydrogen peroxide
  • Hydroxyl radical
102
Q

How do organisms neutralize toxic oxygen?

A

They use enzymes such as:

  • Catalase and peroxidase
  • Superoxide dismutase
  • Superoxide reductase
103
Q

What are 3 heat methods used to control microbial growth?

A
  • Heat sterilization (reach very high temp to kill)
  • Autoclave (kill endospores)
  • Pasteurization (moist low heat, not sterilizing)
104
Q

How does an autoclave work to sterilize objects?

A
  • Sealed device using steam under pressure
  • Raises water temp above 100dC
  • Kills endospores through temperature, not pressure
105
Q

What are the uses of UV radiation?

A
  • Causes modifications and breaks in DNA

- Decontamination of surfaces

106
Q

At what wavelengths would UV radiation be most effective?

A

Between 220 and 300 nm.

107
Q

What are the limitations of UV radiation?

A

Cannot penetrate

  • Solid surfaces
  • Opaque surfaces
  • Light-absorbing surfaces
108
Q

What are the limitations of HEPA filters?

A
  • Pore size varies based on purpose
  • Pores allow liquid or gas to pass through
  • Sterilization is possible if pores trap viruses
109
Q

Ionizaing radition

A

Some substance that’s radioactive, emit beta and gamme particle, emission damage cells.
- limitations, effective against bacteria and dangerous for humans, performed in controlled environment

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