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MICB 3301 > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Plasma Membrane Functions (3.2, 3.6)

A
  • Selectively permeable barrier
  • Mechanical boundary of the cell
  • Nutrient and waste transport systems
  • Location of many metabolic processes (respiration, photosynthesis)
  • Detection of environmental cues for chemotaxis
  • Main site of energy generation
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2
Q

Ribosomes (3.2, 3.6)

A

Protein synthesis

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3
Q

Inclusions (3.2)

A

Storage of carbon, phosphates, and other substances

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4
Q

Periplasmic space (3.2)

A
  • In typical gram-negative bacteria, contains hydrolytic enzymes & binding proteins for nutrient processing and uptake. The area between the plasma membrane and the outer wall.
  • In typical gram-positive bacteria, may be smaller or absent. The area between the plasma membrane and the first layer of peptidoglycan.
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5
Q

Cell wall (3.2 / 3.4)

A
  • Protection from osmotic stress / osmotic lysis
  • Helps maintain cell shape
  • Protects cell from toxic substances
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6
Q

Capsules & Slime layers (3.2)

A
  • Resistance to phagocytosis

- Adherence to surfaces

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7
Q

Fimbriae & Pili (3.2)

A
  • Attachment to surfaces
  • Bacterial conjugation & transformation
  • Twitching & gliding motility
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8
Q

Flagella (3.2)

A

Swimming & swarming motility

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9
Q

Endospore (3.2)

A

Survival under harsh environmental conditions

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10
Q

What is the average size of a bacterium? (3.2)

A

On average, 1.1 - 1.5 um wide & 2.0 - 6. um long.

However, they can be as small as 0.3 um in diameter, or reach sizes up to 600 x 80 um.

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11
Q

What are the five main shapes that bacteria are found in? (3.2)

A

1) Cocci - Small & round
2) Rods - Self-explanatory
3) Vibrios - Comma-shaped
4) Spirilla - Rigid, spiral-shaped. Often have tufts or flagella at one or both ends.
5) Spirochete - Flexible, spiral-shaped. Have a unique internal flagellar arrangement; Undulate when moving

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12
Q

Pleomorphic (3.2)

A

A bacterial type that is variable in shape and lacking a single, characteristic form (AKA not one of the main five)

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13
Q

What is the phylogenetic tree based on? (1.1)

A

SSU rRNA (small subunit ribosomal RNA).

Bacteria & Archaea - 16S rRNA
Eukarya - 18S rRNA

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14
Q

What are the 5 main types of microbes? (1.1)

A

1) Bacteria (Prokaryotic)
2) Archaea (Prokaryotic)
3) Protists (Eukaryotic)
- Ex: Algae, Protozoa
4) Fungi (Eukaryotic)
- Ex: Yeasts, Molds
5) Viruses (Neither)

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15
Q

Robert Hooke (1.2)

A
  • 1600’s

- First observation of microbes3

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16
Q

Antony von Leeuwenhoek (1.2)

A
  • 1600’s
  • Observed that there are both eukaryotic & prokaryotic microbes
  • Made his own primitive microscopes
  • First observed movement of microbes
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17
Q

Redi [A scientist] (1.2)

A
  • 1688

- Shows that flies don’t spontaneously generate (experiment with fly eggs on decaying meat)

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18
Q

Spallanzi [A scientist] (1.2)

A

Found that microbes will not grow in a flask of meat broth if the flask is sealed and boiled

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19
Q

Louis Pasteur (1.2)

A
  • Found that microbes don’t grow in boiled broth until they are introduced from the outside of the flask
  • Used swan-neck flask
  • This proved that the air carries germs
  • Found that certain microbes would ruin wine; Created pasteurization
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20
Q

Joseph Lister (1.2)

A

Developed surgery to prevent microbes from entering wounds

–> This led to the study of host defenses (immunology)

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21
Q

How do large bacteria increase their surface area in order to increase their S/V ratio? (3.2)

A

Often, large bacteria will have very uneven or rough surfaces, which greatly increases their S/V ratio.

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22
Q

Why do bacteria want a high surface area to volume (S/V) ratio?

A

It makes the processing of materials more efficient.

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23
Q

Cell envelope (3.3)

A

The plasma membrane and all of the surrounding layers external to it.

Often consist of the plasma membrane, the cell wall, & at least one additional layer (such as the slime layer or capsule).

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24
Q

Passive Diffusion (3.3)

A

The process by which molecules move from a region of higher concentration to a region of lower concentration. AKA, they move down the concentration gradient. Only very small molecules can do this.

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25
Q

Which things can pass through the cell membrane by passive diffusion? (3.3)

A

Some gases, such as CO2 and O2. Also, H2O passes through via passive diffusion. Bacteria do not use this as a primary method of nutrient uptake due to their nutrient-poor environments.

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26
Q

What does a channeling protein do? (3.3)

A

They form pores in the cell membrane through which substances can pass. This is usually done through facilitated diffusion. There is some specificity here, but far less than carrier proteins.

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27
Q

What does a carrier protein do? (3.3)

A

They carry nutrients through the cell membrane. They are highly specific.

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28
Q

Facilitated diffusion (3.3)

A

Substances pass through the cell membrane with the help of either carrier or channeling proteins. Important: No metabolic energy input is required to perform facilitated diffusion. Not used in bacteria very often, due to their nutrient-poor environments. Use of carrier proteins called ‘permeases’.

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29
Q

Active Transport (3.3)

A

The transport of solute molecules from a low concentration to a higher concentration (against the concentration gradient). Requires the input of metabolic energy (either in the form of ATP or proton motive force).

Three types are observed in bacteria: Primary active transport, Secondary active transport, and Group translocation.

All require carrier proteins.

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30
Q

Metabolic Inhibitors (3.3)

A

Metabolic inhibitors block energy production. Because of this, it inhibits active transport. However, passive transport and facilitated diffusion can still continue.

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31
Q

Primary active transporters (3.3)

A

These facilitate primary active transport (what a surprise!). They use the energy provided by ATP hydrolysis to move substances against a concentration gradient without modifying them.

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32
Q

Robert Koch (1.3)

A
  • First person to find direct evidence that microbes cause disease
  • Studied Bacillus anthrax (which causes anthrax)
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33
Q

Koch’s Postulates (4) (1.3)

A

1) Microbe must be found in all cases of disease, and absent from healthy specimens
2) Microbes must be isolated & grown in pure culture
3) The same disease must result when the isolated microbe is innoculated into a healthy host
4) Sam microbe must be isolated again from the diseased host

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34
Q

Edward Jenner (1.3)

A
  • Made the first vaccine

- Found that material from cowpox lesions protects against smallpox (a worse version of the same disease)

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35
Q

Elie Metchnikoff (1.3)

A

Discovered bacteria-engulfing human cells called macrophages

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36
Q

Wingradsky [A scientist] (1.3)

A

Isolated soil bacteria that oxidize iron, sulfur, & ammonia to obtain energy

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37
Q

Beijerink [A scientist] (1.3)

A

Isolated Nitrogen-fixing bacteria

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38
Q

Nitrogen-Fixing [definition] (1.3)

A

The reduction of atmospheric nitrogen (N2) to ammonia (NH3)

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39
Q

How to bacteria reproduce? (3.2)

A

Bacteria are asexual and reproduce through binary fission

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40
Q

What are the five different kinds of coccus-shaped bacteria? (3.2)

A

1) Coccus - Regular, single-cells, round
2) Diplococcus - In pairs
3) Streptococcus - Chains
4) Staphylococcus - Grape-like clusters
5) Tetrads - 4 cocci in a square

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41
Q

What are long filaments in bacteria & (more commonly) fungi called? What is a network of these called? (3.2)

A

Some bacteria & many fungi form long filaments called hyphae.

A network of hyphae is called a mycelium

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42
Q

Deinococcus [type of bacteria] (3.2)

A
  • Grows in tetrads (cocci)

- Extremely resistant to radiation

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43
Q

Mycoplasma [type of bacteria] (3.2)

A
  • Grows in a pleomorphic shape

- Has a plasma membrane but no cell wall

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44
Q

Cytoplasm (3.6)

A
  • Substance in which inclusions, chromosome, & ribosomes are suspended
  • Mostly water
  • Highly concentrated & highly organized
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45
Q

FtsZ [a protein] (3.6)

A
  • Tubulin-like protein
  • Forms contractile ring
  • Septum formation & cell division
  • Necessary for division of cells
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46
Q

MreB & MbI [proteins] (3.6)

A
  • Actin-like protein
  • May form coils in rod-shaped cells
  • Cell shape definition
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47
Q

What does NAG stand for? (3.4)

A

N-acetylglucosamine

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48
Q

What does NAM stand for? (3.4)

A

N-acetylmuramic acid

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49
Q

Thylakoids (3.4)

A

A photosynthetic membrane with chlorophyll (found in cyanobacteria)

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50
Q

Energy & Carbon Inclusions (3.6)

A
  • Glycogen
  • Poly-Beta-hydroxybutyrate (PHB) granules
    • Stores carbon
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51
Q

Phosphate & Sulfur Inclusions (3.6)

A
  • Polyphosphate (metachromatic) granules

- Sulfur globules

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52
Q

Carbon & Nitrogen Inclusions (3.6)

A
  • Cyanophycin granules

- Chains of amino acids

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53
Q

Carboxysome Inclusion (3.6)

A
  • A microcompartment
  • Cyanobacteria & other CO2-fixing bacteria often have carboxysome inclusions
  • Polyhedral in shape
  • Have a coat of proteins with enzymes inside
  • Photosynthesis provides energy
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54
Q

Carbonic anhydrase (3.6)

A
  • An enzyme inside of a carboxysome inclusion
  • Convert carbonic acid to CO2
  • Rubisco (protein) fixes CO2 into sugar
    • Calvin cycle
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55
Q

Gas Vacuole Inclusion (3.6)

A
  • Found in some aquatic photosynthetic bacteria & anarchaea
  • Allows for floating in aquatic environments
    • Anabena (bacteria) have gas vacuoles
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56
Q

Magnetosome Inclusion (3.6)

A
  • Iron in the form of magnetit (Fe3O4)
  • Orient cells in Earth’s magnetic fields
    • Aquaspirillum (bacteria) have magnetosomes
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57
Q

Describe transcription & translation in bacteria briefly (3.6)

A
  • Occurs in cytoplasm
  • Can occur simultaneously
  • DNA polymerase transcribes DNA –> RNA
  • Ribosomes translate mRNA –> Protein
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58
Q

Nucleoid (3.6)

A
  • Found in cytoplasm
  • Region containing chromosomes
  • Closed, circular, double-stranded DNA
  • Typically 1 chromosome per cell
  • NOT membrane-enclosed (AKA it’s in prokaryotes)
    • Some bacteria have multiple chromosomes
    • Some bacteria have linear chromosomes
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59
Q

Plasmids (3.6)

A
  • Found in cytoplasm
  • Small, closed, circular DNA
  • Exist & replicate independently of the chromosome
  • May carry genes that confer an advantage
    • Conjugate plasmids
    • R plasmid (resistance)
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60
Q

Plasma Membrane Make-Up (3.6)

A
  • Made up of lipids & proteins
  • Lipids form a bilayer w/ embedded proteins
  • Organized, asymmetric, flexible, & dynamic
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61
Q

Plasma Membrane - 3 Parts & The Bonds Between Them (3.6)

A

3 Parts

i) Ethanolamine - Polar, Hydrophilic
ii) Glycerol
iii) Fatty Acids - Nonpolar, Hydrophobic

Bonds Between Them

i) Phosphodiester bond / Phospholipids
- Between ethanolamine & glycerol (I think? Double check this)
ii) Ester bond
- Between the glycerol & the fatty acids
- A stronger Ether bond will replace this in some bacteria

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62
Q

Hopanoids (3.6)

A
  • Not proteins
  • Similar to sterols (cholesterol)
  • Helps stabilize the plasma membrane
  • Not all bacteria have them
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63
Q

Fluid Mosaic Model (3.6)

A

States that membranes are lipid bilayers in which proteins float

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64
Q

Osmosis (3.3 / 3.4)

A

The movement of water across a membrane

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65
Q

Hypotonic solution (3.4)

A
  • Bacteria are often found here
  • A place where the solute concentration is higher inside the cell than outside, which threatens the cell with osmotic lysis
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66
Q

What color do gram positive bacteria stain? What color do gram negative bacteria stain?

A

Gram positive - Purple

Gram negative - Pink / Red
- Can’t retain crystal violet

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67
Q

Peptidoglycan Structure (3.4)

A
  • Thick in Gram +, Thin in Gram -
  • Important component of cell wall in both
  • Polysaccharide-formed subunits
  • Sugar backbones cross-linked by peptides
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68
Q

Polysaccharide Backbone in Peptidoglycan (3.4)

A
  • Cross-linked by peptides
  • Made up of NAG & NAM, alternating with one another
    • NAG: N-acetylglucosamine
    • NAM: N-acetylmuramic acid
  • Beta-1,4-Glycosidic bond holds the sugars in the backbone together

**Figure 3.17 for reference

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69
Q

Lysosome (3.4)

A

Recognizes the Beta-1,4 Glycosidic bond that holds together the sugars in the peptidoglycan polysaccharide backbone & cuts the bond

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70
Q

Why are D-form amino acids commonly used by bacteria? (3.4)

A

The D-form is far less common [than the L-form], and so there is a much lower chance that an enzyme found in nature will be able to degrade it

71
Q

Transpeptidation (3.4)

A

Reaction that catalyzes the reaction between peptide chains of peptidoglycan

*Figure 3.19

72
Q

Peptide Interbridge (3.4)

A
  • Not all bacteria use this

- Often a chain of all ‘Gly,’ but sometimes it is another enzyme of a mix of enzymes

73
Q

Gram-Positive Cell Walls (3.4)

A
  • Primarily peptidoglycan
  • Contain teichoic acids
    • Polymers of glycerol or ribitol
    • Provide additional structure to the peptidoglycan
74
Q

Gram-Negative Cell Walls (3.4)

A
  • Thin layer of peptidoglycan surrounded by outer membrane of lipids (lipopolysaccharide - LPS)
  • Porins - in outer membrane
  • NO teichoic acids
  • LPS - embedded in outer membrane & exend out in hair-like strands
75
Q

Lipopolysaccharide (LPS) [Three parts] (3.4)

A

i) Lipid A
- Fatty acid
- This is the part that extends out of the cell in a hair-like structure
ii) Core polysaccharide
- Sugars
iii) O side chain / O antigen
- Sugars

76
Q

LPS Importance (3.4)

A
  • Protection from host defenses
  • O antigens vary
    • E. coli - O157:H7 (an important strain)
  • Attachment
  • Stability
  • The lipid A portion can act as a toxin and is called an endotoxin
    • Meaning that the toxin is a part of the cell, not just released from the cell
      • Fever, septic shock
77
Q

Capsules (3.4)

A
  • Polysaccharides (usually)
  • Organized, not easily removed from the cell
  • Common in all kinds of bacteria & archaea
78
Q

Slime layers (3.4)

A
  • Polysaccharides
  • Diffuse, unorganized, easily removed
  • Not as common as capsules & S-layers
79
Q

S-layers (3.4)

A
  • Proteins
  • Highly organized
  • Common in all kinds of bacteria & archaea
80
Q

Overview: Layer Functions (3.4)

A
  • Attachment
  • Protection from:
    • Chemicals
    • Harsh environments
      • Dessication (drying out)
    • Bacterial viruses
      • Bacteriophages
    • Host immune response
81
Q

Overview: External Structures (3.7)

A
  • Extend beyond the cell wall
  • Functions:
    • Attachment
    • Horizontal gene transfer
    • Movement
82
Q

Pili (3.7)

A

Thin, protein appendages that are used for attachment

83
Q

Sex pili (3.7)

A
  • Used for conjugation
  • Conjugation: Exchange genetic information from one cell to another (horizontal gene transfer)
  • Not all bacteria have these
84
Q

Type IV Pili (3.7)

A
  • Twitching motility
  • Cycles of extension, attachment, retraction
  • Breaks down as it retracts
  • Kind of like a grappling hook in that it extends, attaches to something, and drags itself toward it
  • Dynamic
85
Q

Flagella (3.7)

A
  • Motility organelles found in all domains of life

- Not all bacteria have flagella (making them non-motile)

86
Q

Peritrichous Flagella (3.7)

A

Flagella coming off in all directions (ex: E. coli)

87
Q

Three types of polar flagella (3.7)

A

Polar - Flagella at the ends of the cell

i) Monotrichous - One flagella at one end
ii) Amphitrichous - One flagella at each end
iii) Lophotrichous - Multiple flagella at one end

88
Q

Three major parts of the Flagella (3.7)

A

i) Basal Body
ii) Hook
iii) Filament

-The flagella is built from the inside of the cell outwards, and has specific proteins to let the cell know when to stop building on certain areas

89
Q

Basal Body (3.7)

A
  • A rod in a series of rings
  • Functions as the motor - can spin & turn
  • Uses proton motive force for energy
90
Q

Proton Motive Force (3.7)

A
  • Creates ATP (but does not use ATP to fuel the flagella’s movement)
  • Protons move through part of the basal body and the difference in charge is what allows the basal body to move
91
Q

Counterclockwise rotation of Flagella (3.7)

A
  • Forward Run

- Prolong the run

92
Q

Clockwise rotation of Flagella (3.7)

A
  • Tumbling (changing direction)

- Shortens the run

93
Q

Attractants & Their Effect on Flagella (3.7)

A
  • Cause counterclockwise rotation of flagella (forward run)
  • Flagella bundle (like putting hair into a pony tail)
  • Create a biased run that causes a net movement toward the attractant
94
Q

Repellents & Their Effects on Flagella (3.7)

A
  • Cause clockwise rotation of flagella (tumbling)
  • The flagella fly apart
  • Cells change direction to avoid the repellent
95
Q

Chemoreceptors (3.7)

A
  • Proteins embedded in the plasma membrane which detect attractants & repellents
  • Look at Fig. 14.22 for more reference
96
Q

Random walk (3.7)

A

The overall movement of the cell, based on the runs & tumbles of the flagella. A biased random walk occurs when the cell wants to move towards and attractant or away from a repellent.

97
Q

Chemotaxis (3.7)

A

Sensory system that enables microbes to move toward or away from specific chemicals (uses chemoreceptors)

98
Q

Haloquadratum [archaea] (4.1)

A
  • An extremophile

- Can withstand extremely high salt content (halophile)

99
Q

Pyrococcus furiosus [archaea] (4.1)

A

An extremophile that is used as a source of Pfu polymerase in PCR reactions

100
Q

Five major characteristics of Virsuses (6.1)

A
  • Acellular
  • Non-living
  • Infect living cells to replicate
  • Depend upon the host’s metabolism
  • *Obligate, intracellular parasite**
101
Q

What are viruses made of? (6.2)

A
  • Viruses are composed of protein & nucleic acid
  • Very simple structure
  • Very small
102
Q

What are the largest & smallest viruses? (6.2)

A

Smallest - Parvovirus

Largest - Mimivirus

103
Q

Virion (6.2)

A

The complete virus particle

104
Q

Capsid (6.2)

A

Protein coat around the genome

105
Q

Nucleocapsid (6.2)

A

The nucleic acid and the capsid together

106
Q

Protomer (6.2)

A

Protein subunits of the capsid

107
Q

Icosahedral [virus shape] (6.2)

A
  • Most common/efficient way for viruses to enclose their genome
  • 20 triangular faces
    • Capsomers: Ring-shaped units that make up each face
      • Each capsomer is made up of 5 or 6 protomers
  • Ex: Polyomavirus
108
Q

Helical [virus shape] (6.2)

A
  • Hollow tubes with protein walls
  • Ex: Tubulovirus
  • Ex: Tobacco mosaic virus
  • Ex: Influenza virus (also an enveloped virus)
109
Q

Enveloped [virus shape] (6.2)

A
  • The envelope comes from the host cell’s membrane
  • Contains protein spikes, which are encoded by the virus
  • Ex: HIV
  • Ex: Influenza virus
  • Ex: Herpesvirus
110
Q

-Binal [virus shape] (6.2)

A
  • Bacteriophages
    • Infect bacteria
  • Genome found in the head
  • Has the following components:
    • Head
    • Collar
    • Helical Sheath
    • Tail Pins
    • Tail Fibers
    • Core/Tube (Hollow)
  • Reference Fig. 6.7
111
Q

Tegument proteins (6.2)

A

Proteins between the capsid and the envelope. Not found in all viruses that contain an envelope.

112
Q

HIV (6.2 / 38.3)

A
  • Viral spike protein gp120 binds to the host cell
  • CD4 receptor & CCR5 co-receptor
  • Reverse transcriptase makes DNA copy of viral RNA genome
  • Pg. 867 figure
113
Q

Neuraminidase (6.3)

A

Cleaves host lipids & proteins to release virus

114
Q

Hemagglutanin (6.3)

A

Binds host sialic acid

115
Q

Influenza virus (6.3)

A
  • Contains neuraminidase & hemagglutanin
  • Fig. 6.4
  • Contains the following components:
    • Neuraminidase spike
    • Hemagglutanin spike
    • Envelope (lipid bilayer)
    • RNA replicate
    • Segmented RNA genome
116
Q

Viral genomes (6.4)

A
  • Can be DNA or RNA
  • Single-stranded OR Double-stranded
  • Linear OR circular
  • Envodes viral proteins
117
Q

Viral Multiplication / Infectious Cycle [5 steps] (6.4)

A

1) Attach to host cell
2) Entry & uncoating
3) Synthesis of viral proteins & nucleic acids
4) Assembly of capsids
5) Release of virions

118
Q

Tropism (6.3)

A

The targeting of the virus for a particular cell, tissue, or organ

119
Q

How do viruses attach to the cell they are infecting? (6.3)

A

Viral surface proteins mediate attachment to host receptors such as carbohydrates, proteins, and lipids

120
Q

In what two ways do viruses enter the animal host cell? (6.3)

A

1) Fusion with the host membrane
2) Endocytosis

Fig. 6.10

121
Q

What occurs once the virus has infected an animal cell? (6.3)

A
  • The viral genome is replicated

- Viral mRNA is made & used to make viral proteins

122
Q

How do DNA viruses replicate? (6.3)

A
  • Typically replicate in the nucleus of the host cell
  • Use hosts’s DNA polymerase
    • Exception: Herpes virus uses their own DNA polymerase
123
Q

How do RNA viruses replicate? (6.3)

A
  • Typically replicate in the cytoplasm
  • Use viral RNA replicases (they must make their own RNA replicases because the host cell generally will not contain them)
  • Ex: Influenza
124
Q

How do retroviruses replicate? (6.3)

A
  • Use reverse transcriptase to copy their RNA genome into DNA
  • The DNA copy becomes integrated into the host’s genome using viral integrase
  • Ex: HIV
125
Q

How do viruses undergo synthesis? (6.3)

A
  • All viruses make proteins using host ribosomes (viruses can’t make their own ribosomes)
  • Translation occurs in the cytoplasm of the infected cell
126
Q

How do viruses undergo assembly? (6.3)

A
  • Assembly occurs in either the cytoplasm or the nucleus
  • In this stage, it puts the genome inside of the capsid
  • Spike proteins are made & put into the membrane of the infected cell
127
Q

How are viruses released from the infected cell? (6.3)

A
  • Lysis
  • Budding - Occurs in enveloped viruses
    • Membrane lipids surround capsid to form envelope
128
Q

Viroids (6.6)

A
  • Smaller than a virus
  • Made up of RNA only
  • Can’t encode protein
  • May pair up with plant RNA to cause RNA silencing
129
Q

Prions (6.7)

A
  • Infectious protein (protein only)
  • Cause of some neurodegenerative diseases, such as Mad Cow & Scrapie
  • Its abnormal protein form causes misfolding & aggregation of the normal proteins in the host
  • Causes plaque formation & cell death
130
Q

Nutrients (3.3)

A
  • Required for growth

- Substances used in biosynthesis and energy release

131
Q

Macronutrients (3.3)

A
  • Elements required in large amounts for cell function

- Ex: C, O, H, N, S, P, Fe

132
Q

Micronutrients (3.3)

A
  • Elements required in small amounts for cell function

- Ex: Co, Cu, Zn, Mg

133
Q

Growth Factors (3.3)

A
  • Organic compounds that a microbe can’t make itself
  • Three major types:
    • Amino acids
    • Purines & pyrimidines
    • Vitamins
134
Q

What are the three main sources of nitrogen for microbes? (3.3)

A

1) Ammonia (NH3)
2) Nitrate (NO3)
3) Atmospheric nitrogen (N2)

135
Q

Ammonia (NH3) in microbes (3.3)

A

-Can diffuse into cells and is then incorporated into cell material

136
Q

Nitrate (NO3) in microbes (3.3)

A

-First, it is reduced into ammonia by assimilatory nitrate reduction– then it is incorporated into the cell

137
Q

Atmospheric nitrogen in microbes (3.3)

A

-Use nitrogen fixation to reduce the N2 into ammonia (NH3), where it is then incorporated into the cell

138
Q

Azobacter [microbe] (3.3)

A
  • Nitrogen-fixing

- Free-living in soil

139
Q

Rhizobium [microbe] (3.3)

A
  • Nitrogen-fixing

- In symbiosis with plants

140
Q

How must food enter a microbe in order to sustain its rapid growth [4 things]? (3.3)

A

Food must enter:

1) At high rates
2) Across membranes
3) In selective fashions
4) Often against the concentration gradient

141
Q

ABC Transporters (3.3)

A
  • “ATP-Binding Cassette”
  • Occurs in all domains of life
  • Used in passive transport
  • Two types
    • Uptake ABCs : Move nutrients in
    • Efflux ABC’s : Multidrug efflux pumps (moves out)
  • Fig. 3.13
  • Very important!
142
Q

Secondary Active Transport (3.3)

A
  • Uses potential energy of ion gradients
    • Ex: Electron transport across membrane generates proton gradient
      • Can use this gradient to do work
  • Symport, antiport
  • Fig. 3.12
143
Q

Active Transport: Group Translocation/Metabolic Energy (3.3)

A
  • Fig. 3.14
  • The nutrient becomes chemically altered in the process
  • Energy comes from phosphoenolpyruvate (PEP)
    • Attaches phosphate (P) to sugars
  • Ex: Phosphotransferase system (PTS) occurs in all bacteria
144
Q

Iron uptake in microbes (3.3)

A
  • Microbes release siderophores to acquire Fe

- Ex: Enterobactin - An E. coli siderophore

145
Q

Siderophore (3.3)

A
  • A compound made by the microbe to acquire Fe from its environment
  • Fe complex is then transported into the cell, often using ABC transporters
146
Q

Eukaryotic microbe reproductive strategies (7.1)

A
  • Sexual & asexual
    • Budding: Asexual
  • Haploid & diploid
147
Q

Prokaryotic microbe reproductive strategies (7.1)

A
  • Only asexual
    • Binary fission
  • Only haploid cells
148
Q

Describe the difference between viral budding & bacterial budding (7.1, 6.3)

A
  • Viral: Becomes enveloped by host cell’s plasma membrane as it is exiting the cell
  • Bacterial: An asexual reproduction technique
149
Q

Binary fission [4 steps] (7.1)

A

1) DNA replicates
2) Cell elongates, chromosomes separate
3) Septum forms
4) Cell divides

150
Q

Batch culture (7.6)

A
  • A closed vessel, single batch of medium used to grow bacterium
  • Where a growth curve can be observed
151
Q

Lag phase (7.6)

A
  • First phase on growth curve
  • No growth– cells synthesizing new components, replenishing, & adapting to new environment
  • Length of phase can vary wildly
152
Q

Exponential / Log Phase (7.6)

A
  • Balanced, constant growth
    • Double in number in regular intervals
  • Rate of growth expressed as generation (or doubling) time
    • Time required for cells to divide
    • Range: 7 min - Over 24 hrs
153
Q

Growth Curve (7.6)

A
  • Measures how a culture grows in a closed system
  • Fig. 7.30
  • Fig 7.32
154
Q

Stationary Phase (7.6)

A
  • Population growth ceases
    • Lower level of nutrients
    • Some bacteria release toxic by-products that begin killing off the culture
      • Ex: Yeast produces ethanol when fermenting alcohol
  • Some microbes undergo drastic changes, such as sporulation
155
Q

Sporulation (7.6)

A
  • Occurs in nutrient-limiting conditions
  • Some microbes will become stress-resistant, dormant spores through this process
  • Ex: Bacillus, Clostridium
156
Q

Death Phase (7.6)

A
  • Cells dying, usually at an exponential rate
  • Often through cell lysis
  • Death rate may slow or be reversed via resistant bacteria
157
Q

Continuous culture system (7.6)

A
  • Can maintain microbial populations in exponential growth
  • Rate of new medium in = Rate of medium w/ microbes & waste out
  • Chemostat
  • Fig. 7.22
158
Q

Measuring microbial growth [3 ways] (7.7)

A

1) Direct cell counts
- Counting chambers (Petroff-Hauser)
2) Viable cell counts
- Plating - Colony Forming Units (CFUs)
3) Turbidity measurements
- Measured with a spectrophotometer
- Microbial cells scatter light
- More turbid –> More cells –> More light scattered

159
Q

Thermophile (7.3)

A

Can survive & grow at high temps (40 C - 80 C)

160
Q

Psychrophiles (7.3)

A

Can survive very cold temperatures (0 C - 20 C)

161
Q

Mesophiles (7.3)

A

Can survive in moderate temperatures (20 C - 45 C)

162
Q

Hyperthermophiles (7.3)

A

Can survive extremely high temperatures (80 C - 122 C)

  • Current record holder is 122 C
  • Theorized that non could live above 150 C, as that is where ATP degenerates
163
Q

Osmophiles (7.3)

A

Live in highly concentrated environments

164
Q

Halophiles (7.3)

A

Live in high salt concentrations

165
Q

Acidophiles (7.3)

A

Live in very low pH’s

-Ex: In the Berkeley Pit, the pH is 2 & some microbes live there

166
Q

Obligate Anaerobes (7.3)

A

Live with no oxygen / Oxygen is toxic to them

-Ex: Winogradsky column

167
Q

Obligate Aerobe (7.3)

A

Need oxygen

  • Live at top of liquid culture
  • Fig 7.13
168
Q

Facultative anaerobe (7.3)

A

Prefer oxygen

  • Live towards the top of a liquid culture, but can live lower down
  • Fig. 7.13
169
Q

Aerotolerant anaerobe (7.3)

A

Ignore oxygen

  • Live spread out equally in a liquid culture
  • Fig. 7.13
170
Q

Microaerophile (7.3)

A

Grow at 2 - 10% down the liquid culture

  • -Need oxygen, but not too much
  • Fig. 7.13
171
Q

Why are some microbes sensitive to oxygen? (7.3)

A
  • Oxygen can be reduced to toxic products called Reactive Oxygen Species
    • Ex: O2 (superoxide radical)
    • Ex: H2O2 (hydrogen peroxide)
  • Microbes in the presence of oxygen need enzymes to detoxify
172
Q

What enzymes are used to detoxify oxygen? (7.3)

A
  • Superoxide dismutase
    • O2 + O2 + 2(H) –> 2(H2O2) + O2
  • Catalase
    • H2O2 + H2O2 –> 2(H2O) + O2
173
Q

How do thermophiles adapt to high temperature areas? (7.3)

A
  • Proteins stabilized
    • Increased Hydrogen & Covalent bonds
    • Molecular chaperones - Bind & refold damaged proteins
  • DNA stabilized
    • Synthesize proteins to coat DNA

MICB 3301 (14 decks)

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