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BIO-360: Microbiology > Exam 1 (Ch. 1, 3, 5, & 6) > Flashcards

Exam 1 (Ch. 1, 3, 5, & 6) Flashcards

Monday, February 26th

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1
Q

Who was the first researcher to address Spontaneous Generation, and what was his experiment?

A

Redi

Experimented with meats and maggots in three different flasks:
1. Unsealed flask (had maggots)
2. Sealed flask (no maggots)
3. Flask covered with gauze, containing airflow (no maggots)

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2
Q

What was the FIRST experiment to PROVE Spontaneous Generation?

A

Needham boiled beef or plant extracts (sealed with corks), and saw them get cloudy with microbial growth

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3
Q

Antoni van Leeuwenhoek discovered “wee animalcules.”

What are these?

A

Microbes/bacteria!

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4
Q

Who was the one to DISPROVE Spontaneous Generation?

What was his experiment in doing so?

A

Pasteur

He boiled broths in a swan-neck flask that were open to the air, but the bacteria and dust from the air settled in the bend of the flask - the broth remained sterile indefinitely

Once tilted so that the sterile broth came in contact with the bacteria and dust, bacterial growth then occurred

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5
Q

How long did Pasteur’s flasks remain empty of bacteria?

A

18 months

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6
Q

What is the purpose of Fermentation in the 1800s?

A

to preserve food

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7
Q

How could you prevent spoilage of wine (acid production) but still get fermentation of the grape juice into alcohol?

A

Heat up the grape juice to kill bacteria (sterile), then introduce yeast

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8
Q

What is the Germ Theory of Disease?

A

1857: “If a particular disease is typically accompanied by the SAME symptoms in ALL affected individuals, then these diseases are caused by a specific germ called a PATHOGEN”

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9
Q

What are Koch’s Postulates? (4)

A
  1. The microorganism MUST be found in EVERY case of the disease
  2. The agent MUST be isolated and grown OUTSIDE of the host
  3. When introduced to a new host, the agent MUST cause the SAME disease
  4. The same agent MUST be found in the experimental diseased host
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10
Q

What are the THREE Domains of Living Organisms?

A
  1. Archaea
  2. Eukarya
  3. Bacteria
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11
Q

What are the major differences between the Three Domains of Life?

A
  1. Bacteria: peptidoglycan present in the cell wall (not seen in others)
  2. Eukarya: contains a nuclear membrane, mitochondria, chloroplasts (on plants and algal cells), and cytoskeleton (not seen in others)
  3. Archaea: found frequently in extreme environments (eukarya are not, bacteria is found in all environments)
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12
Q

True/False: Prokaryotes are always smaller than Eukaryotes.

A

False

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13
Q

True/False: Bacteria and Archaea are Prokaryotes, but Eukarya are Eukaryotes.

A

True - bacteria and archaea are unicellular

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14
Q

Are Viruses living?

A

No - they only consist of either DNA or RNA, surrounded by a protein coat

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15
Q

What are Viroids made of and where are they commonly found?

A

consist only of RNA, no protein coat

commonly found in plants

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16
Q

What are Prions made of?

A

consist only of protein, no DNA or RNA

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17
Q

List the 6 common shapes of bacterial cells.

A
  1. Coccus: “spherical”
    -e.g., staph
  2. Bacillus: “rod-shaped”
    -e.g., E. coli
  3. Coccobacillus: intermediate “spherical and rod” shape
  4. Vibrio: “comma-shaped”
    -e.g., cholera
  5. Spirillum: “slight corkscrew-shape”
  6. Spirochete: “full corkscrew-shape”
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18
Q

What are the 3 groupings of bacterial cells? What does the grouping tell us about the number of planes the bacteria are able to divide on

A
  1. Chains: cell divides in ONE plane
  2. Packets: cell divides in TWO OR MORE planes PERPENDICULAR to one another
  3. Clusters: cell divides in SEVERAL planes at RANDOM
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19
Q

What eukaryotic cells have cell walls?

A

Plant Cells

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20
Q

Why do you think animal cells don’t have cell walls?

A

-Would limit mobility
-Limits size of the cell

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21
Q

What is the importance of bacterial cell walls?

A

-protection against mechanical damage
-protection against osmotic rupture (lysis)
-one of the most important sites for attack by antibiotics
-provide ligand for adherence and receptor sites for drugs or viruses
-cause symptoms of disease in animals
-provide for immunological distinction and immunological variation among strains

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22
Q

What is the purpose of the Gram Stain, and what do the results show?

A

To differentiate bacteria based on cell wall structure - either POSITIVE OR NEGATIVE

Gram-positive bacteria lack an outer membrane but are surrounded by layers of peptidoglycan many times thicker than is found in the Gram-negatives

Gram-negative bacteria are surrounded by a thin peptidoglycan cell wall, which itself is surrounded by an OUTER MEMBRANE containing lipopolysaccharide

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23
Q

Which type of bacteria, Gram-Positive or Negative, is more resistant to antibiotics, and why?

A

Gram-Negative

Any alteration in the outer membrane by Gram-negative bacteria like changing the hydrophobic properties or mutations in porins and other factors, can create resistance

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24
Q

The cell walls of bacteria contain a layer of Peptidoglycan.

What are the two main sugar derivatives in the formation of this layer (particularly in the Glycan chains)?

A
  1. N-acetylglucosamine (NAG)
  2. N-acetylmuramic acid (NAM)
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25
Q

The cell walls of bacteria contain a layer of Peptidoglycan.

What sugar is the cell wall similar to?

A

Glucose

The structures of NAM and NAG of the glycan chains are very similar to the structure of glucose!

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26
Q

The cell walls of bacteria contain a layer of Peptidoglycan.

How are the layers linked?

A

they are cross-linked either directly or through an additional bridging peptide of varying amino acid length and composition

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27
Q

How does the linkage of peptidoglycan layers differ between Gram-positive and Gram-negative bacteria?

A

Gram-positive bacteria contain a pentaglycine cross-bridge, gram-negative bacteria do not

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28
Q

What are the two types of prokaryotic organisms?

A

Archaea and Bacteria

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29
Q

Gram-negative bacteria have an outer membrane with several components.

What does Lipopolysaccharide (LPS) do?

A

Acts as a permeability barrier

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30
Q

Why is LPS also known an endotoxin?

A

LPS is the biologically active portion of an endotoxin

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31
Q

Gram-negative bacteria have an outer membrane with several components.

What do Mg2+ Bridges do?

A

stabilize LPS, essential for permeability

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32
Q

Gram-negative bacteria have an outer membrane with several components.

What does Braun Lipoprotein do?

A

anchors outer membrane to peptidoglycan

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33
Q

Gram-negative bacteria have an outer membrane with several components.

What does Omp C and Omp F Porins do?

A

proteins that form pores for hydrophilic molecules

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34
Q

Gram-negative bacteria have an outer membrane with several components.

What does Omp A protein do?

A

receptor for viruses, stabilize mating cells

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35
Q

What are the distinguishing structures between a Gram-positive and a Gram-negative bacteria?

(+) depicts positive presence
(-) depicts negative presence

A

Peptidoglycan: Thin (-), Thick (+)
Teichoic Acids (+)
Periplasm (-)
Outer Membrane (-)
Endotoxin (LPS) (-)
Porin Proteins (-)

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36
Q

Why is M. pneumonia considered a bacterium if it has no cell wall?

i.e., what other characteristics would be useful in classifying it as a bacterium?

A

Has bacterial-like DNA and ribosomes

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37
Q

What are the functions of a prokaryotic plasma membrane?

A
  1. Osmotic or permeability barrier
  2. Location of transport systems for solutes
  3. Energy-generating functions
  4. Synthesis of membrane lipids (including LPS)
  5. Synthesis of peptidoglycan
  6. Secretion of extracytoplasmic proteins
  7. Location of specialized enzyme systems
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38
Q

True/False: Just like in eukaryotic cells, osmosis occurs in prokaryotic cells.

A

True

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39
Q

What is Proton Motive Force in active transport?

A

an electrochemical gradient of protons across their cytoplasmic membrane

e.g., uniport, antiport

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40
Q

What does an ABC transport system do as active transport?

A

specific binding protein in periplasmic space delivers a molecule to a transport protein, moving the molecule into the cell

e.g., maltose

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41
Q

What is Group Translocation in active transport?

A

a molecule (like glucose) is phosphorylated as it enters the cell, thus transporting but also being transformed

THIS IS THE FIRST STEP IN GLYCOLYSIS

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42
Q

What is the purpose of a Glycocalyx (capsule)?

A

-Enables bacteria to adhere to specific surfaces (and to each other)
-protects against desiccation
-traps food
-protects from phagocytosis
-compose of polysaccharides and polypeptides

43
Q

Why is a capsule considered a virulence factor?

A

it is protected from phagocytosis and it enables the bacteria to adhere to specific surfaces (and each other)….e.g., dental plaque

44
Q

What is the difference between a Capsule and a Slime Layer?

A

Capsule = “tighter;” well-defined outer layers of uniform diameter on bacterial surfaces
-THINK SWEATER

Slime Layer = “Looser;” extend outwards from bacterial surfaces in a loosely organized network of material
-THINK SNUGGIE

45
Q

What is the difference between a Peritrichouse and a Polar flagella?

A

Peritrichous = many hairs, surrounding the bacteria

Polar = at one end

46
Q

How does the flagella structure differ in Gram-positive and Gram-negative bacteria?

A

Flagella from Gram-positive and Gram-negative bacteria are essentially identical, except that flagella from Gram-negative bacteria extend through a second, outer membrane that is absent in Gram-positive bacteria

What this means is that there are outer protein rings and inner protein rings (4) rather than (2) in Gram-positive

47
Q

Spirochetes move in a corkscrew fashion.

What type of flagella do they have?

A

internal flagella called an axial filament

48
Q

Where does the energy come from for bacterial flagella?

A

Proton Motive Force

49
Q

Fimbriae is a type of bacterial pili.

What is its function?

A

adhesion of the bacteria to surfaces or to other bacteria - can lead to colonization

50
Q

What is the purpose of a sex pilus (or conjugation pilus)?

A

allow the transfer of DNA between bacteria, in the process of bacterial conjugation

51
Q

What are the two forms in which bacterial DNA is found?

A
  1. In one large circular chromosome
  2. Plasmids
52
Q

What is a bacterial ribosome composed of?

A

the 30S and 50S subunit, each contributes to specific functions in protein synthesis

Top: RNA and protein in large subunit
Middle: tRNAs in A, P, and E sites
Bottom: RNA and protein in small subunit

53
Q

What is the purpose of an Endospore and who has them?

A

Provides bacteria a means of survival for long periods of times and in harsh conditions, rather than a means of reproducing

These belong to the genera Bacillus and Clostridium

54
Q

How are Endospores produced?

A
  1. DNA is duplicated, vegetative growth stops
  2. A septum form, dividing the cell asymmetrically
  3. The larger compartment then engulfs the smaller compartment, forming a forespore within a mother cell
  4. Peptidoglycan-containing material is laid down between the two membranes that now surround the forespore
  5. The mother cell is degraded and the endospore is released
55
Q

Where is ATP made in bacterial cells if they do not contain a mitochondria?

A

plasma membrane (and cytoplasm)

56
Q

Define:

Catabolism
Anabolism
Metabolism

A

Catabolism: breakdown of complex molecules (e.g., glucose) for energy

Anabolism: building of complex molecules from numerous simple ones
-(e.g., subunits, macromolecules, cell structures)

Metabolism: Catabolism + Anabolism

57
Q

What is Oxidation? Reduction?

A

Oxidation = loss of electrons
“OIL”

Reduction = gain of electrons
“RIG”

58
Q

What are Enzymes and what do they do?

A

“Proteins that serve as catalysts”
-speed up rate of reaction
-is not consumed in the reaction
-lowers activation energy of a reaction
-can be constitutive or inducible

59
Q

What do co-factors allow for on an enzyme?

A

they are co-enzymes (or trace elements) that hold the substrate in place or allow for a reaction to speed up

60
Q

What are some factors that change enzyme activity?

A

Temperature
pH
Substrate concentration

Activity may reach a certain peak before dropping (e.g., enzyme activity drops in higher or lower temps, or low/high pH) or reach a saturation point/constant

61
Q

Competitive Inhibition: PABA is used in the biosynthetic pathway for the production of folic acid.

Why is this drug not toxic to humans?

A

We take in all folic acid from our diet, we do not produce it

62
Q

What are the three types of enzyme inhibitors?

A
  1. Non-Competitive Inhibition by Regulatory Molecules
    -inhibitor temporarily changes the enzyme, altering its relative affinity for the substrate
  2. Non-Competitive Inhibition by Enzyme Poisons
    -inhibitor permanently changes the enzyme, rendering it non-functional
  3. Competitive Inhibition
    -inhibitor binds to the active site of the enzyme, obstructing the access of the substrate (e.g., sulfa drugs, antibacterial meds)
63
Q

What is an example of when a bacterium would want to turn on/off a certain enzyme?

A

Turn on/off enzyme to aid in forming an endospore

64
Q

The structure of penicillin mimics that of the amino acids and binds the active site of the enzyme transpeptidase.

Is this Competitive or Allosteric?

A

Competitive Inhibition - the penicillin is binding directly to the active site

65
Q

How does a cell make ATP?

A
  1. Uses an energy source (e.g., photons, organic/inorganic molecules…“food”)
  2. Uses oxidation/reduction reactions
  3. Uses electron carriers to accept electrons from energy source as it is oxidized
66
Q

What factors are important in determining which pathway the cell will use at any given time for ATP generation?

A

Oxygen availability? -> aerobic respiration
Sulfate availability -> anaerobic respiration
Fermentation

67
Q

Does anaerobic respiration have an electron acceptor?

A

Yes - a molecule other than oxygen (e.g., nitrate, sulfate)

68
Q

What are the final electron acceptors in Aerobic respiration, Anaerobic respiration, and Fermentation

A

Aerobic = oxygen

Anaerobic = molecule other than oxygen (nitrate, sulfate)

Fermentation = organic molecule (pyruvate)

69
Q

What is the role of the Pentose Phosphate Cycle

A

produces pentose phosphates (for nucleotide synthesis) and NADPH

70
Q

What are the 2 biological precursors produced from the Pentose-Phosphate pathway?

A
  1. Amino Acid Synthesis
  2. Lipid Synthesis
71
Q

What is the role of the Pentose Phosphate Cycle in ATP production?

A

components of this cycle are used in the various steps of glycolysis, such as the reduction to glucose 6-phosphate, which enters step 1 of glycolysis

72
Q

What are precursor metabolites and where do they come from?

A

intermediate molecules in catabolic and anabolic pathways that can be either oxidized to generate ATP or can be used to synthesize macromolecular subunits

they derive from central metabolic pathways, like Glycolysis and the Pentose-Phosphate Cycle

73
Q

What is the maximum theoretical energy yield of ATP?

A

38 ATP molecules

74
Q

What are some differences of the ETC in prokaryotes than eukaryotes?

A

-occurs in the plasma membrane
-different orientation of proteins
-final electron acceptor could be sulfate (anaerobic respiration)
-iron-containing compounds take up electrons only
-flavin-compounds and quinones take up both electrons and H+

75
Q

True/False: ATP Synthase uses proton motive force.

A

True

76
Q

What is Fermentation?

A

enables cells to produce chemical energy from the breakdown of glucose without the help of oxygen. That gives anaerobic organisms the advantage of thriving in environments without oxygen

77
Q

Why is Fermentation done if it doesn’t directly produce energy?

A

While it does not produce energy itself, it does allow more energy to be produced through glycolysis, important if oxygen is not present

78
Q

Why are there different end-products of fermentation? List a few different end products and some “uses” of these end products,

A

the formation of these end products depends on the presence of certain key enzymes in the bacterium, which differ from each one

EXAMPLES:
-Lactic Acid = yogurt, cheddar cheese
-Ethanol, CO2 = beer, wine
-Propionic Acid, CO2 = swiss cheese
-Acetone, Isopropanol = nail polish remover, rubbing alcohol

79
Q

What are hydrolytic enzymes?

A

Enzymes that hydrolyze carbohydrates, proteins, or fats in a bacteria to produce energy and carbon synthesizing metabolic products

This can help to categorize and identify the metabolic processes of bacteria species

80
Q

In the lab, how might you go about obtaining a pure culture (think about first
lab)?

A

using appropriate aseptic techniques!

81
Q

In what way do bacteria divide? How often do they divide?

A

by binary fission (around every 20 mins!)

82
Q

True/False: Bacteria growth is exponential.

A

True

83
Q

Be able to sketch a growth curve and label the axes, know the different phases

What is Lag Phase?

A

Phase 1: bacteria is needing to turn on tools for growth

84
Q

Be able to sketch a growth curve and label the axes, know the different phases

What is Log Phase?

A

Phase 2: Growth > Death; there is great access to nutrients

85
Q

Be able to sketch a growth curve and label the axes, know the different phases

What is Stationary Phase?

A

Phase 3: Growth = Death

86
Q

Be able to sketch a growth curve and label the axes, know the different phases

What is Death Phase?

A

Phase 4: Death > Growth

87
Q

What is the formula for determining bacterial growth? (semi-log)

A

Nt = No x 2^n

No = number of organisms
n = number of generations

Nt = time

NOTE: If it is said that 18 bacteria divide every 25 minutes for 3 hours (180 mins), that means that 7.2 generations have occurred (180 total mins / 25 mins per division)

88
Q

Calculate the number of bacteria in a glass of milk left at room temperature for 4 hours if there were 20 bacteria in the glass, to begin with. The generation time of this bacterium is 30 minutes at room temp

A

No = 20
n = 30 mins for 4 hours

240 mins / 30 mins = 8 generations

20 x 2^8

20 x 256 = 5,120 bacteria

89
Q

Would you expect more or fewer bacteria in a glass of milk if the glass had been left in a 37C incubator? In the refrigerator? Why?

A

An incubator - depending on the bacteria, it will thrive greater in a warmer confined environment. A fridge would possibly lead to growth, but not as much due to the lower temperature

90
Q

What are factors that affect bacterial growth?

A

-temperature
-pH
-osmotic pressure
-availability of oxygen
-nutrients

91
Q

What are the 4 classifications based on energy and carbon source?

A
  1. Photoautotrophs
  2. Photoheterotrophs
  3. Chemoautotrophs
  4. Chemoheterotrophs

photo = light
chemo - chemical compounds
auto = carbon dioxide
hetero = organic compounds

92
Q

What types of organisms fall under the following classifications:

  1. Photoautotrophs
  2. Photoheterotrophs
  3. Chemoautotrophs
  4. Chemheterotrophs
A
  1. Photoautotrophs: plants, algae, cyanobacteria, green sulfur bacteria, purple sulfur bacteria
  2. Photoheterotrophs: green nonsulfur bacteria, purple nonsulfer bacteria, some archaea
  3. Chemoautotrophs: hydrogen, sulfur, and nitrifying bacteria, some archaea
  4. Chemoheterotrophs:
    Aerobic: most animals, fungi, protozoa, many bacteria
    Anaerobic: some animals, protozoa, bacteria, and archaea
    Fermentation: some bacteria, yeasts, and archaea
93
Q

How do chemoautotrophs derive energy?

A

by removing electrons from inorganic compounds

94
Q

Why is the source of carbon important?

A

this is the source for making precursor metabolites

95
Q

List two bacterial growth ranges and their range.

A
  1. Psychrophiles (-5 - 15C)
  2. Psychrotrophs (20 - 30C)
  3. Mesophiles (25 - 45C)
  4. Thermophiles (45 - 70 C)
  5. Hyperthermophiles (70 - 110C)
96
Q

At what temperature do most human pathogens have optimal growth temps?

A

37 C

Exceptions: syphilis, leprosy

97
Q

Different microorganisms have different requirements for oxygen.

List each category and explain the role/effect of oxygen

A
  1. Obligate aerobes: needs oxygen; cells will be present at the top of the culture
  2. Obligate anaerobes: killed by the presence of oxygen; cells will be present at the bottom of the culture
  3. Facultative anaerobes: cells will be found throughout the culture
  4. Microaerophiles: need some oxygen; cells found partway in the culture
  5. Aerotolerant anaerobes: unaffected by oxygen levels; cells found throughout the culture
98
Q

Clostridium perfringens, an obligate anaerobe, is the cause of gas gangrene.

What is an effective treatment to kill the organism?

A

exposure to air will kill the organism considering it dies in the presence of oxygen. Debridement of tissue allows for this exposure.

99
Q

What are some ways to count numbers of bacteria and/or growth of a bacterial population?

A
  1. Direct cell count with Hemocytometer
  2. Coulter Counter (automatic cell counter)
  3. Serial dilution and pour plate
  4. Membrane filtration
  5. Turbidity
100
Q

In a closed culture, what is different with our original bacterial growth curve?

A

After the death phase, we have a phase of prolonged decline

101
Q

What is a Biofilm? Give an example

A

a community of cells, that often adhere to surfaces, that are slime-enclosed, exhibiting different properties than when they are free-floating

EXAMPLES:
-plaque on the surface of teeth (S. mutans)
-Bioluminescence in the Hawaiian Bobtail Squid by V. fisheri

102
Q

How do cells in biofilms communicate with each other?

A

Through the secretion of AHL, which builds up in the cell and triggers certain genes when concentrations reach a threshold level

this is called QUORUM SENSING

103
Q

YOU MAY BE REQUIRED TO DRAW:

-THE STRUCTURE OF PEPTIDOGLYCAN
-GRAM+ AND GRAM- CELL WALLS
-GROWTH CURVE (LABELED)

A

Peptidoglycan:

NAG-NAM-NAG-NAM-NAG-NAM
|
|amino acids
________
|
|amino acids
NAM-NAG-NAM-NAG-NAM-NAG

BIO-360: Microbiology (6 decks)

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