Exam 1 Flashcards
(173 cards)
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
2
Q
Ribosomes (3.2, 3.6)
A
Protein synthesis
3
Q
Inclusions (3.2)
A
Storage of carbon, phosphates, and other substances
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.
5
Q
Cell wall (3.2 / 3.4)
A
- Protection from osmotic stress / osmotic lysis
- Helps maintain cell shape
- Protects cell from toxic substances
6
Q
Capsules & Slime layers (3.2)
A
- Resistance to phagocytosis
- Adherence to surfaces
7
Q
Fimbriae & Pili (3.2)
A
- Attachment to surfaces
- Bacterial conjugation & transformation
- Twitching & gliding motility
8
Q
Flagella (3.2)
A
Swimming & swarming motility
9
Q
Endospore (3.2)
A
Survival under harsh environmental conditions
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.
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
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)
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
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)
15
Q
Robert Hooke (1.2)
A
- 1600’s
- First observation of microbes3
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
17
Q
Redi [A scientist] (1.2)
A
- 1688
- Shows that flies don’t spontaneously generate (experiment with fly eggs on decaying meat)
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
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
20
Q
Joseph Lister (1.2)
A
Developed surgery to prevent microbes from entering wounds
–> This led to the study of host defenses (immunology)
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.
22
Q
Why do bacteria want a high surface area to volume (S/V) ratio?
A
It makes the processing of materials more efficient.
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).
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.
25
Which things can pass through the cell membrane by passive diffusion? (3.3)
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.
26
What does a channeling protein do? (3.3)
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.
27
What does a carrier protein do? (3.3)
They carry nutrients through the cell membrane. They are highly specific.
28
Facilitated diffusion (3.3)
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'.
29
Active Transport (3.3)
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.
30
Metabolic Inhibitors (3.3)
Metabolic inhibitors block energy production. Because of this, it inhibits active transport. However, passive transport and facilitated diffusion can still continue.
31
Primary active transporters (3.3)
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.
32
Robert Koch (1.3)
- First person to find direct evidence that microbes cause disease
- Studied Bacillus anthrax (which causes anthrax)
33
Koch's Postulates (4) (1.3)
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
34
Edward Jenner (1.3)
- Made the first vaccine
| - Found that material from cowpox lesions protects against smallpox (a worse version of the same disease)
35
Elie Metchnikoff (1.3)
Discovered bacteria-engulfing human cells called macrophages
36
Wingradsky [A scientist] (1.3)
Isolated soil bacteria that oxidize iron, sulfur, & ammonia to obtain energy
37
Beijerink [A scientist] (1.3)
Isolated Nitrogen-fixing bacteria
38
Nitrogen-Fixing [definition] (1.3)
The reduction of atmospheric nitrogen (N2) to ammonia (NH3)
39
How to bacteria reproduce? (3.2)
Bacteria are asexual and reproduce through binary fission
40
What are the five different kinds of coccus-shaped bacteria? (3.2)
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
41
What are long filaments in bacteria & (more commonly) fungi called? What is a network of these called? (3.2)
Some bacteria & many fungi form long filaments called hyphae.
A network of hyphae is called a mycelium
42
Deinococcus [type of bacteria] (3.2)
- Grows in tetrads (cocci)
| - Extremely resistant to radiation
43
Mycoplasma [type of bacteria] (3.2)
- Grows in a pleomorphic shape
| - Has a plasma membrane but no cell wall
44
Cytoplasm (3.6)
- Substance in which inclusions, chromosome, & ribosomes are suspended
- Mostly water
- Highly concentrated & highly organized
45
FtsZ [a protein] (3.6)
- Tubulin-like protein
- Forms contractile ring
- Septum formation & cell division
* Necessary for division of cells
46
MreB & MbI [proteins] (3.6)
- Actin-like protein
- May form coils in rod-shaped cells
- Cell shape definition
47
What does NAG stand for? (3.4)
N-acetylglucosamine
48
What does NAM stand for? (3.4)
N-acetylmuramic acid
49
Thylakoids (3.4)
A photosynthetic membrane with chlorophyll (found in cyanobacteria)
50
Energy & Carbon Inclusions (3.6)
- Glycogen
- Poly-Beta-hydroxybutyrate (PHB) granules
- Stores carbon
51
Phosphate & Sulfur Inclusions (3.6)
- Polyphosphate (metachromatic) granules
| - Sulfur globules
52
Carbon & Nitrogen Inclusions (3.6)
- Cyanophycin granules
| - Chains of amino acids
53
Carboxysome Inclusion (3.6)
- 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
54
Carbonic anhydrase (3.6)
- An enzyme inside of a carboxysome inclusion
- Convert carbonic acid to CO2
- Rubisco (protein) fixes CO2 into sugar
- Calvin cycle
55
Gas Vacuole Inclusion (3.6)
- Found in some aquatic photosynthetic bacteria & anarchaea
- Allows for floating in aquatic environments
- Anabena (bacteria) have gas vacuoles
56
Magnetosome Inclusion (3.6)
- Iron in the form of magnetit (Fe3O4)
- Orient cells in Earth's magnetic fields
- Aquaspirillum (bacteria) have magnetosomes
57
Describe transcription & translation in bacteria briefly (3.6)
- Occurs in cytoplasm
- Can occur simultaneously
- DNA polymerase transcribes DNA --> RNA
- Ribosomes translate mRNA --> Protein
58
Nucleoid (3.6)
- 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
59
Plasmids (3.6)
- 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)
60
Plasma Membrane Make-Up (3.6)
- Made up of lipids & proteins
- Lipids form a bilayer w/ embedded proteins
- Organized, asymmetric, flexible, & dynamic
61
Plasma Membrane - 3 Parts & The Bonds Between Them (3.6)
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
62
Hopanoids (3.6)
- Not proteins
- Similar to sterols (cholesterol)
- Helps stabilize the plasma membrane
- Not all bacteria have them
63
Fluid Mosaic Model (3.6)
States that membranes are lipid bilayers in which proteins float
64
Osmosis (3.3 / 3.4)
The movement of water across a membrane
65
Hypotonic solution (3.4)
- 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
66
What color do gram positive bacteria stain? What color do gram negative bacteria stain?
Gram positive - Purple
Gram negative - Pink / Red
- Can't retain crystal violet
67
Peptidoglycan Structure (3.4)
- Thick in Gram +, Thin in Gram -
- Important component of cell wall in both
- Polysaccharide-formed subunits
- Sugar backbones cross-linked by peptides
68
Polysaccharide Backbone in Peptidoglycan (3.4)
- 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
69
Lysosome (3.4)
Recognizes the Beta-1,4 Glycosidic bond that holds together the sugars in the peptidoglycan polysaccharide backbone & cuts the bond
70
Why are D-form amino acids commonly used by bacteria? (3.4)
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
Transpeptidation (3.4)
Reaction that catalyzes the reaction between peptide chains of peptidoglycan
*Figure 3.19
72
Peptide Interbridge (3.4)
- Not all bacteria use this
| - Often a chain of all 'Gly,' but sometimes it is another enzyme of a mix of enzymes
73
Gram-Positive Cell Walls (3.4)
- Primarily peptidoglycan
- Contain teichoic acids
- Polymers of glycerol or ribitol
- Provide additional structure to the peptidoglycan
74
Gram-Negative Cell Walls (3.4)
- 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
Lipopolysaccharide (LPS) [Three parts] (3.4)
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
LPS Importance (3.4)
- 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
Capsules (3.4)
- Polysaccharides (usually)
- Organized, not easily removed from the cell
- Common in all kinds of bacteria & archaea
78
Slime layers (3.4)
- Polysaccharides
- Diffuse, unorganized, easily removed
- Not as common as capsules & S-layers
79
S-layers (3.4)
- Proteins
- Highly organized
- Common in all kinds of bacteria & archaea
80
Overview: Layer Functions (3.4)
- Attachment
- Protection from:
- Chemicals
- Harsh environments
- Dessication (drying out)
- Bacterial viruses
- Bacteriophages
- Host immune response
81
Overview: External Structures (3.7)
- Extend beyond the cell wall
- Functions:
- Attachment
- Horizontal gene transfer
- Movement
82
Pili (3.7)
Thin, protein appendages that are used for attachment
83
Sex pili (3.7)
- Used for conjugation
- Conjugation: Exchange genetic information from one cell to another (horizontal gene transfer)
- Not all bacteria have these
84
Type IV Pili (3.7)
- 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
Flagella (3.7)
- Motility organelles found in all domains of life
| - Not all bacteria have flagella (making them non-motile)
86
Peritrichous Flagella (3.7)
Flagella coming off in all directions (ex: E. coli)
87
Three types of polar flagella (3.7)
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
Three major parts of the Flagella (3.7)
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
Basal Body (3.7)
- A rod in a series of rings
- Functions as the motor - can spin & turn
- Uses proton motive force for energy
90
Proton Motive Force (3.7)
- 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
Counterclockwise rotation of Flagella (3.7)
- Forward Run
| - Prolong the run
92
Clockwise rotation of Flagella (3.7)
- Tumbling (changing direction)
| - Shortens the run
93
Attractants & Their Effect on Flagella (3.7)
- 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
Repellents & Their Effects on Flagella (3.7)
- Cause clockwise rotation of flagella (tumbling)
- The flagella fly apart
- Cells change direction to avoid the repellent
95
Chemoreceptors (3.7)
- Proteins embedded in the plasma membrane which detect attractants & repellents
- Look at Fig. 14.22 for more reference
96
Random walk (3.7)
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
Chemotaxis (3.7)
Sensory system that enables microbes to move toward or away from specific chemicals (uses chemoreceptors)
98
Haloquadratum [archaea] (4.1)
- An extremophile
| - Can withstand extremely high salt content (halophile)
99
Pyrococcus furiosus [archaea] (4.1)
An extremophile that is used as a source of Pfu polymerase in PCR reactions
100
Five major characteristics of Virsuses (6.1)
- Acellular
- Non-living
- Infect living cells to replicate
- Depend upon the host's metabolism
* *Obligate, intracellular parasite**
101
What are viruses made of? (6.2)
- Viruses are composed of protein & nucleic acid
- Very simple structure
- Very small
102
What are the largest & smallest viruses? (6.2)
Smallest - Parvovirus
| Largest - Mimivirus
103
Virion (6.2)
The complete virus particle
104
Capsid (6.2)
Protein coat around the genome
105
Nucleocapsid (6.2)
The nucleic acid and the capsid together
106
Protomer (6.2)
Protein subunits of the capsid
107
Icosahedral [virus shape] (6.2)
- 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
Helical [virus shape] (6.2)
- Hollow tubes with protein walls
- Ex: Tubulovirus
- Ex: Tobacco mosaic virus
- Ex: Influenza virus (also an enveloped virus)
109
Enveloped [virus shape] (6.2)
- 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
-Binal [virus shape] (6.2)
- 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
Tegument proteins (6.2)
Proteins between the capsid and the envelope. Not found in all viruses that contain an envelope.
112
HIV (6.2 / 38.3)
- 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
Neuraminidase (6.3)
Cleaves host lipids & proteins to release virus
114
Hemagglutanin (6.3)
Binds host sialic acid
115
Influenza virus (6.3)
- Contains neuraminidase & hemagglutanin
- Fig. 6.4
- Contains the following components:
- Neuraminidase spike
- Hemagglutanin spike
- Envelope (lipid bilayer)
- RNA replicate
- Segmented RNA genome
116
Viral genomes (6.4)
- Can be DNA or RNA
- Single-stranded OR Double-stranded
- Linear OR circular
- Envodes viral proteins
117
Viral Multiplication / Infectious Cycle [5 steps] (6.4)
1) Attach to host cell
2) Entry & uncoating
3) Synthesis of viral proteins & nucleic acids
4) Assembly of capsids
5) Release of virions
118
Tropism (6.3)
The targeting of the virus for a particular cell, tissue, or organ
119
How do viruses attach to the cell they are infecting? (6.3)
Viral surface proteins mediate attachment to host receptors such as carbohydrates, proteins, and lipids
120
In what two ways do viruses enter the animal host cell? (6.3)
1) Fusion with the host membrane
2) Endocytosis
Fig. 6.10
121
What occurs once the virus has infected an animal cell? (6.3)
- The viral genome is replicated
| - Viral mRNA is made & used to make viral proteins
122
How do DNA viruses replicate? (6.3)
- Typically replicate in the nucleus of the host cell
- Use hosts's DNA polymerase
- Exception: Herpes virus uses their own DNA polymerase
123
How do RNA viruses replicate? (6.3)
- 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
How do retroviruses replicate? (6.3)
- 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
How do viruses undergo synthesis? (6.3)
- All viruses make proteins using host ribosomes (viruses can't make their own ribosomes)
- Translation occurs in the cytoplasm of the infected cell
126
How do viruses undergo assembly? (6.3)
- 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
How are viruses released from the infected cell? (6.3)
- Lysis
- Budding - Occurs in enveloped viruses
- Membrane lipids surround capsid to form envelope
128
Viroids (6.6)
- Smaller than a virus
- Made up of RNA only
- Can't encode protein
- May pair up with plant RNA to cause RNA silencing
129
Prions (6.7)
- 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
Nutrients (3.3)
- Required for growth
| - Substances used in biosynthesis and energy release
131
Macronutrients (3.3)
- Elements required in large amounts for cell function
| - Ex: C, O, H, N, S, P, Fe
132
Micronutrients (3.3)
- Elements required in small amounts for cell function
| - Ex: Co, Cu, Zn, Mg
133
Growth Factors (3.3)
- Organic compounds that a microbe can't make itself
- Three major types:
- Amino acids
- Purines & pyrimidines
- Vitamins
134
What are the three main sources of nitrogen for microbes? (3.3)
1) Ammonia (NH3)
2) Nitrate (NO3)
3) Atmospheric nitrogen (N2)
135
Ammonia (NH3) in microbes (3.3)
-Can diffuse into cells and is then incorporated into cell material
136
Nitrate (NO3) in microbes (3.3)
-First, it is reduced into ammonia by assimilatory nitrate reduction-- then it is incorporated into the cell
137
Atmospheric nitrogen in microbes (3.3)
-Use nitrogen fixation to reduce the N2 into ammonia (NH3), where it is then incorporated into the cell
138
Azobacter [microbe] (3.3)
- Nitrogen-fixing
| - Free-living in soil
139
Rhizobium [microbe] (3.3)
- Nitrogen-fixing
| - In symbiosis with plants
140
How must food enter a microbe in order to sustain its rapid growth [4 things]? (3.3)
Food must enter:
1) At high rates
2) Across membranes
3) In selective fashions
4) Often against the concentration gradient
141
ABC Transporters (3.3)
- "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
Secondary Active Transport (3.3)
- 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
Active Transport: Group Translocation/Metabolic Energy (3.3)
- 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
Iron uptake in microbes (3.3)
- Microbes release siderophores to acquire Fe
| - Ex: Enterobactin - An E. coli siderophore
145
Siderophore (3.3)
- 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
Eukaryotic microbe reproductive strategies (7.1)
- Sexual & asexual
- Budding: Asexual
- Haploid & diploid
147
Prokaryotic microbe reproductive strategies (7.1)
- Only asexual
- Binary fission
- Only haploid cells
148
Describe the difference between viral budding & bacterial budding (7.1, 6.3)
- Viral: Becomes enveloped by host cell's plasma membrane as it is exiting the cell
- Bacterial: An asexual reproduction technique
149
Binary fission [4 steps] (7.1)
1) DNA replicates
2) Cell elongates, chromosomes separate
3) Septum forms
4) Cell divides
150
Batch culture (7.6)
- A closed vessel, single batch of medium used to grow bacterium
- Where a growth curve can be observed
151
Lag phase (7.6)
- First phase on growth curve
- No growth-- cells synthesizing new components, replenishing, & adapting to new environment
- Length of phase can vary wildly
152
Exponential / Log Phase (7.6)
- 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
Growth Curve (7.6)
- Measures how a culture grows in a closed system
- Fig. 7.30
- Fig 7.32
154
Stationary Phase (7.6)
- 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
Sporulation (7.6)
- Occurs in nutrient-limiting conditions
- Some microbes will become stress-resistant, dormant spores through this process
- Ex: Bacillus, Clostridium
156
Death Phase (7.6)
- Cells dying, usually at an exponential rate
- Often through cell lysis
- Death rate may slow or be reversed via resistant bacteria
157
Continuous culture system (7.6)
- Can maintain microbial populations in exponential growth
- Rate of new medium in = Rate of medium w/ microbes & waste out
- Chemostat
- Fig. 7.22
158
Measuring microbial growth [3 ways] (7.7)
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
Thermophile (7.3)
Can survive & grow at high temps (40 C - 80 C)
160
Psychrophiles (7.3)
Can survive very cold temperatures (0 C - 20 C)
161
Mesophiles (7.3)
Can survive in moderate temperatures (20 C - 45 C)
162
Hyperthermophiles (7.3)
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
Osmophiles (7.3)
Live in highly concentrated environments
164
Halophiles (7.3)
Live in high salt concentrations
165
Acidophiles (7.3)
Live in very low pH's
| -Ex: In the Berkeley Pit, the pH is 2 & some microbes live there
166
Obligate Anaerobes (7.3)
Live with no oxygen / Oxygen is toxic to them
| -Ex: Winogradsky column
167
Obligate Aerobe (7.3)
Need oxygen
- Live at top of liquid culture
- Fig 7.13
168
Facultative anaerobe (7.3)
Prefer oxygen
- Live towards the top of a liquid culture, but can live lower down
- Fig. 7.13
169
Aerotolerant anaerobe (7.3)
Ignore oxygen
- Live spread out equally in a liquid culture
- Fig. 7.13
170
Microaerophile (7.3)
Grow at 2 - 10% down the liquid culture
- -Need oxygen, but not too much
- Fig. 7.13
171
Why are some microbes sensitive to oxygen? (7.3)
- 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
What enzymes are used to detoxify oxygen? (7.3)
- Superoxide dismutase
- O2 + O2 + 2(H) --> 2(H2O2) + O2
- Catalase
- H2O2 + H2O2 --> 2(H2O) + O2
173
How do thermophiles adapt to high temperature areas? (7.3)
- Proteins stabilized
- Increased Hydrogen & Covalent bonds
- Molecular chaperones - Bind & refold damaged proteins
- DNA stabilized
- Synthesize proteins to coat DNA
