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Life on Earth: Microbes - BI276 > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

Flagella

A

Long filamentous appendages which propel bacteria

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2
Q

Four possible flagella arrangements

A

Monotrichous
Amphitrichous
Lophotrichous
Peritichous

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3
Q

Monotrichous

A

Single, Polar

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4
Q

Amphitrichous

A

Tuft at each end

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5
Q

Lophotrichous

A

Two or more at one pole

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6
Q

Peritichous

A

Distributed over entire cell
- They move faster because of the amount of flagella

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7
Q

Flagellar structure

A

Filament, Hook, Basal Body

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8
Q

Filament

A

Consists of flagellin protein arranged in chains intertwined around a hollow core

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9
Q

Hook

A

Protein to which filament is attached

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10
Q

Basal body

A

Anchors flagellum to the cell wall and cytoplasmic membrane; consists of a central rod inserted into a series of rings

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11
Q

Mot protein

A

Motor for the flagella and spins the rings

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12
Q

Gram-negative Basal body

A

Gram-negative bacteria contain two pairs of rings in the basal body; outer pair anchored to the cell wall and inner pair anchored to the plasma membrane

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13
Q

Gram-positive Basal body

A

Gram-positive bacteria has two rings, one in the cell membrane and one in the cell wall

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14
Q

How do bacteria move

A

Movement is achieved through the rotation of the flagellum from the basal body either clockwise or counterclockwise

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15
Q

Run / Swim

A

Continuous movement in one direction which can be interrupted by a “tumble”

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16
Q

Tumble

A

An abrupt change in direction of the bacteria.

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17
Q

What can cause a bacteria to tumble

A

Bactria are usually moving towards a nutrition source or moving away from something toxic.

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18
Q

Taxis

A

Movement of a bacterium toward or away from a stimulus

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19
Q

Chemotaxis

A

Movement towards or away from a chemical

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20
Q

Phototaxis

A

Movement toward or away from light

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21
Q

Magnetotaxis

A

Movement toward or away from a magnetic field

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22
Q

Fimbriae & Pili

A
  • Typically found on Gram-negative bacteria
  • Hairlike projections; shorter, straighter, thinner than flagella
  • Consist of a protein: pilin

They are not responsible for any movement but come out of the cell wall

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23
Q

Fimbriae

A

Occur at bacterial cell poles or evenly distributed over entire cell surface

Few or several hundred per cell

Primary role in adherence to surfaces or other cells
e.g. Neisseria gonorrhoeae

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24
Q

Pili

A

Usually longer than fimbriae

One or two per cell

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25
Q

Macronutrients

A

C, N, P, S, K, Mg, Ca, Na

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26
Q

Nutrients

A

Required substances for growth

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27
Q

Chemically defined

A

Exact chemical composition is known

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28
Q

Undefined (complex)

A

Uses digests of animal or plant products, exact composition not entirely known
- Undefined medium are easier to use in a lab because they can grow faster

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29
Q

Selective medium

A

Contains compounds that selectively inhibit the growth of some microorganisms and not others

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30
Q

Differential medium

A

Contains an indicator which distinguishes between chemical reactions generated by different species of bacteria.
- Will not inhibit growth but will allow you to distinguish

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31
Q

Pure culture

A

Contains one single type of microorganism

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32
Q

Amphibolic pathways

A

Reaction pathways that utilize roles of both catabolism (a break down) and anabolism (a build up)

  • Transfer of ATP provides a link between catabolic and anabolic reactions
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33
Q

Energy

A

Ability to work

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34
Q

Free energy

A

Energy released that is available to do useful work

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35
Q

Delta G not prime

A

Change in free energy under standard conditions of pH and temperature

pH -7.0
Temp 25C

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36
Q

Negative delta G not prime

A

Exergonic, releases energy

Spontaneous

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37
Q

Positive delta G not prime

A

Endergonic, takes in energy

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38
Q

G not sub F

A

Free energy of formation, energy that is released or required for the formation of a molecule

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39
Q

Activation energy

A

Amount of energy needed to disrupt the stable arrangement of a given molecule

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40
Q

Reaction rate

A

Frequency of collisions containing sufficient energy to create a reaction

(the speed at which a chemical reaction takes place)

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41
Q

Enzymes

A

Biological catalysts which speed up a reaction and act on a specific substrate at its active site

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42
Q

Enzyme-substrate complex

A

A temporary molecule formed when the substrate binds to the enzyme, lowers the activation of a particular reaction

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43
Q

What is enzyme activity affected by

A
  • Temperature
  • pH
  • Substrate concentration
  • Inhibitors
44
Q

Feedback inhibition

A

Prevents the cell from wasting chemical resources

End product of a reaction can inhibit one of the enzymes earlier in the pathway

45
Q

Oxidation reaction

A

Oxidation reactions are chemical processes where a substance loses electrons, increasing its oxidation state.
- Generating energy
- Mostly have dehydrogenation reactions

46
Q

Reduction reaction

A

A reaction where a substance gains electrons oand decreases its oxidation state
Gain of one or more electrons

47
Q

Dehydrogenation reaction

A

A type of oxidation reaction involving the loss of hydrogen atoms

48
Q

ATP generation

A

Formation of ATP allows the cell to store potential energy

49
Q

Phosphorylation

A

Addition of P to a chemical compound A(help generate energy)

50
Q

Substrate-level phosphorylation

A

The direct transfer of a phosphate group to ADP to form ATP

ATP is generated after a high-energy phosphate group transfers from a phosphorylated substrate to ADP

51
Q

Oxidative phosphorylation

A

The process of forming ATP via the transfer of electrons

Involves the ETC that is a series of compunds that pass electrons from one to another

  • The electron carrier is usually NAD
  • Occurs in plasma membrane of prokaryotes
52
Q

Photophosphorylation

A

Occurs only in photosynthetic cells

Light energy is converted to chemical energy of ATP and NADPH
- Light trapping pigment is chlorophyll

53
Q

Carbohydrate Catabolism

A

Breakdown of carbohydrate molecules to produce energy

54
Q

Processes used in glucose catabolism

A

Cellular respiration

Fermentation

55
Q

Alternatives to classic glycolysis

A

Pentose phosphate pathway
- only one (E.coli)

Entner-Doudoroff pathway
- More common in gram-negative (Rhizobia)

56
Q

Aerobic respiration

A

Aerobic respiration is the process by which cells generate energy (ATP) in the presence of oxygen. It is the most efficient way for cells to produce energy and occurs primarily in the mitochondria of eukaryotic cells

  • Krebs cycle (citric acid cycle)
  • Potential energy in acetyl CoA is released throughout a series of reactions
  • Final electron acceptor must be an inorganic compound other than oxygen
    e.g. Pseudomonas can use nitrate
    Desulfovibrio uses sulfate
57
Q

Electron Transport Chain

A

Sequence of carrier molecules capable of both oxidation and reduction

Stepwise release of energy as electronsare passed through the chain

Three classes of carrier molecules (flavoproteins, cytochromes, ubiquinones)

58
Q

Chemiosmosis

A

The process used by cells to generate energy in the form of ATP, which is essential for powering cellular activities.

This process takes place in the mitochondria during cellular respiration and in the chloroplasts during photosynthesis.

Energy released when protons moving along a gradient used to synthesize ATP

This mechanism is used in both prokaryotes and eukaryotic cells

59
Q

Fermentation

A

Conversion of sugars (mainly glucose) into other compounds in the absence of oxygen

Does not require oxygen

Does not require use of Kerbs cycle or electron transport chain

Uses an organic as the final e acceptor

Produces small amounts of ATP

60
Q

Lactic acid fermentation

A

Following glycolysis pyruvate is reduced to lactic acid
Energy generated remains stored in lactic acid

e.g. Streptococcus and Lactobacillus (suicide bacteria, don’t stop producing acid and it can exceed the buffer)

  • Lactic acid fermentation is generating lactate
61
Q

Alcohol fermentation

A

Following glycolysis reduction of pyruvate leads to formation of acetaldehyde and then ethonal

Low energy yield as energy is in ethanol

62
Q

Heterolactic

A

Heterolactics produce lactic acid as well as other alcohols or acids
- Produce more than one end product
- Can be unique to prokaryotes and there environmental conditions, so they can have many end products
- E Coli is a heterolactic

63
Q

Lipid and Protein Catabolism

A

Use lipases to break down lipid material to fatty acid and glycerol components

  • Can be used to clean up spills
  • If there is an oil spill and a bacteria works for awhile then stops, that means the environmental conditions changed. The change might be really small but can affect the bacteria.

Krebs cycle will function in oxidation of glycerol and fatty acids
e.g. beta oxidation of petroleum

Extracellular production of proteases and peptidases break proteins down into amino acid components

Amino acids readily pass through prokaryotic membrane but require further conversion in order to be catabolized
e.g. deamination, decarboxylation, dehydrogenation

64
Q

Bacterial growth

A

Bacterial growth refers to the process by which bacteria reproduce and increase in number over time

Need to graphically represent large populations

Need to determine microbial numbers

Growth has traditionally been defined as an increase in cell numbers in microbiology

65
Q

Why do we need to know why bacteria grow

A

Because we need to control disease, and to control them we need to know how they grow

66
Q

Bacterial division

A

Bacterial growth results in an increase in cell number via binary fission (1 into 2)

67
Q

How do enormous populations of bacteria happen

A

Result from doubling growth pattern

The daughter cell is the same size as the mother cell

68
Q

Min protein

A

Min proteins in bacteria control the timing of cell division by regulating the location of FtsZ, a protein that forms the septal ring

They prevent FtsZ from binding to cell poles.
Min proteins inhibit FtsZ from binding to the cell pole membrane, ensuring that bacterial cell division occurs in the middle of the cell.

69
Q

Fts protein

A

Filmentes temperature sensitive protein

Fts protein interaction results in the formation of a divisome

Assisted by series of Min proteins

70
Q

Divisome dictates what?

A

Divisome dictates synthesis of new cytoplasmic membrane and cell wall material in both directions until cell length has doubled

71
Q

Invagination

A

When the proteins build a bridge to start division

72
Q

MreB

A

Major shape-determining protein

Coccus-shaped bacteria (the default shape for prokaryotes) lack MreB

73
Q

New wall synthesis

A

Small openings in the wall are created by autolysins at FtsZ ring point

New wall material is added across openings assisted by bactoprenol

74
Q

Transpeptidation

A

The formation of new peptide cross-links

  • Penicillin interferes with transpeptidation, it helps control bacteria growth and prevents them from multiplying
  • Strengthens the cell wall
75
Q

Generation time (doubling time)

A

Time required for a cell to divide and its population to divide

Environmental conditions will influence generation time and vary with the specific organism
- Everything from the original cell has to double, not every organism is going to reproduce itself at the same rate

76
Q

Phases of bacterial growth

A

Bacterial growth phases can be represented in a batch (closed) system using a growth curve

Four basic phases of growth: lag, log, stationary and death

  • To see these phases batch conditions are needed
  • In a closed system there is only a certain amount of nutrition
77
Q

Lag phase

A

Period of little or no cell division when cells freshly inoculated into new media

Intense metabolic activity including synthesis of enzymes

78
Q

Log phase

A

Once cell division begins, a period of exponential growth follows during which generation time is constant

Logarithmic plot results in a straight line

Cells are more sensitive to adverse conditions during this period
- Because they are going through reproduction and are the most vulnerable

79
Q

Stationary phase

A

Growth rate slows during this period (in response to some physical or chemical limitation)

Number of deaths balance number of new cells produced
- Number of cells dying match the number of cells growing, it’s a net number

80
Q

Death phase

A

When the number of deaths in the population exceeds the number of new cells formed

Also called logarithmic decline phase

Continues until population dies out or greatly diminishes

81
Q

Continuous growth

A

Continuous culture is an open system (e.g. chemostat)

  • Constant/continuous flow of nutrients into the system
  • There is an in and an out (humans are kind of like chemostats)
  • To control a chemostat we can decided the dilution rate, the rate at which the nutrition reaches them.
  • The one thing you can control is the dilution rate
82
Q

Batch culture

A

Fixed volume and closed system

83
Q

Chemostat

A

Controls both growth rate and population density

84
Q

5 main things that effect bacteria growth, how you can control there growth

A

pH, Temperature, Oxygen, Nutrients, Water activity

85
Q

Microbial Growth - Temperature

A

Can affect microbial growth positively or negatively

Temperature classes of microorganisms can be defined by cardinal temperatures

Psychrophile
Mesophile
Thermophile
Hyperthermophile

Each species has its own minimum, optimum and maximum growth temperature (cardinal growth temperatures)

86
Q

Psychrophile

A

Favour cold temperature
(15 or less)

87
Q

Mesophile

A

Favour moderate temperature
(25-40)

88
Q

Thermophile

A

Favour higher temperatures
(above 45)

89
Q

Hyperthermophile

A

Favour extremely high temperature (above 80)

90
Q

Cold environments

A

Isolate psychrophiles where environment is constantly cold

Psychrotolerant microorganisms are more widely distributed; important in food spoilage

Spoilage cold-active enzymes have greater amounts of alpha-helix and lesser amounts of beta- sheet secondary structure

Active transport occurs optimally at low temperatures

Cytoplasmic membrane contains higher concentrations of concentration fatty acids

Freezing temperatures may prevent cell growth but do not necessitate cell death

91
Q

Thermal environments

A

High temperature environments are restricted in nature

Soils in full sunlight may be heated above 50oC

Intracellular enzymes and proteins thermostable

Cytoplasmic membrane richer in saturated fatty acids to optimize stability and function at higher temperatures

Hyperthermophiles (Archaea) have C40 hydrocarbons instead of fatty acids in the membrane

92
Q

Microbial Growth - pH

A

Optimal growth pH refers to the external environment

Most bacteria grow optimally in a narrow pH range (6.5-7.5)

Most natural environments have pH values between 5 and 9

Recall: acidophile and alkaliphile

Buffers are added to microbial culture media to assist in pH stability during growth

Intracellular compensating systems if pH is away from the optimum

93
Q

Microbial Growth - aw

A

Water activity is a measure of the available water in a substance for microbial growth, and it directly influences the ability of bacteria to survive and reproduce. It ranges from 0 (completely dry, no available water) to 1 (pure water). Bacteria require a certain level of water activity to grow, as they rely on water for cellular processes, nutrient absorption, and waste removal.

Usually cell experiences equal water balance

Environments with high salt concentrations require tolerance to lower aw

Xerophiles
Osmophiles

Intolerant bacteria may suffer loss of water internally to the external environment resulting in plasmolysis

94
Q

Xerophiles

A

Capable of growth in very dry environments

95
Q

Osmophiles

A

Can grow in the presence of high sugar concentrations

96
Q

Obligate aerobes

A

Microorganisms requiring oxygen to live

97
Q

Toxic forms of oxygen

A

Singlet oxygen
Superoxide anion
Hydrogen peroxide
Hydroxyl radical

98
Q

Facultative anaerobes

A

Microorganisms that use oxygen when it is present but can continue to grow in its absence

99
Q

Obligate anaerobes

A

Bacteria cannot use oxygen for energy-yielding reactions and are often harmed by it

Obligate anaerobes do not produce enzymes to neutralize

100
Q

Microbial Growth - Oxygen

A

Tolerant microorganisms require enzymes such as superoxide dismutase (SOD) to neutralize toxic intermediates

Obligate anaerobes do not produce enzymes to neutralize

101
Q

Aerotolerant anaerobes

A

Cannot use oxygen for growth but tolerate its presence

102
Q

Microaerophiles

A

Grow only at low oxygen tension but do require it for growth

103
Q

Enzymes that destruct toxic oxygen

A

Catalase
Peroxidase
Superoxide dismutase

104
Q

Microbial Growth - N, S, P

A

Required for synthesis of cellular material

Nitrogen used to form amino acids

Sulfur used in amino acids and vitamins

Phosphorus is essential for nucleic acid synthesis and phospholipid membrane structure

105
Q

Superoxide dismutase (SOD)

A

Enzyme used by tolerate microorganisms to neutralize the toxic parts of oxygen

Obligate anaerobes don’t have these enzymes

Life on Earth: Microbes - BI276 (3 decks)

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