Microbes
SA/V & Nutrient uptake
Growth rate is proportional to nutrient uptake
Bacteria Storage Form of Sugar
Usually glycogen Sometimes cellulose Never starch
Prokaryote Cell Membrane
Protein Anchor
Site of many proteins for transport and bioenergetics
Prokaryote Cell Membrane
Energy Conservation
Membrane is used for proton motif force
Triclosan
Chemical in soap that inhibits enoyl reductase, killing prokaryotes
Chemoorganotroph
Use organic molecules (glucose, acetate, etc) to affix O2
Chemolithotrophs
Use inorganic molecules (H2, Fe, NH4+) to affix O2
Hopanoids
Present instead of sterols in archaea
Ether Linkage
Used instead of ester linkage for lipid linkage in archaea
Lipid Composition of Bacteria
Phospholipids
Lipid Composition of Archaea
Sulfolipids Glycolipids Nonpolar isoprenoid lipids Phospholipids
3 Characteristics of Active Transport
1. Saturation Effect 2. Highly Specific 3. Number of transport proteins is highly regulated
3 Types of Simple Transport
Driven by energy of proton motif force 1. Antiporter 2. Uniporter 3. Symporter
Antiporter
Transport a molecule across a membrane while simulataneously transporting a second molecule in the opposite direction.
Uniporter
Transports a molecule in a single direction across the membrane
Symporter
Cotransporters. Transport one molecule along with another substance, usually a proton.
Group Translocation
Involves a series of proteins in the transport event. Driven by phosphoenolypyruvate
Phosphoenolpyruvate
Drives group translocation
ABC System
Transport involving three components: 1. A substrate binding protein 2. A membrane-integrated transporter 3. ATP hydrolyzing protein
Membrane Transporters
(Alpha Helix)
All membrane transporters contain 12 alpha helix domains that weave back and forth through the membrane to form a channel
Periplasmic Binding Protein
ATP Binding Protein
Involved in ABC transport Periplasmic Binding Protein is on the outside of the membrane while the ATP binding protein is on the inside
Sec System
Translocase. Used to transport proteins out of cell or into membrane
How do bacteria (and some archaea) maintain shape and rigidity?
Cell Wall
What acids cause cell wall to be negatively charged?
Teichoic acid Lipoteichoic acid
Two Sugar Derivitives of Peptidoglycan
N-acetylglucosamine N-acetylmuramic acid
Amino Acids of Peptidoglycan
L-alanine D-alanine D-glutamic acid Lysine or DAP
Techoic Acid of Peptidoglycan
Used to attach bacteria to host cell
Outer membrane of Gram negative bacteria
Outer membrane are anchored to peptidoglycan via lypoproteins
Paripathis Space
Area between peptidoglycan and other layers of cell wall
Lipopolysaccharide (LPS) layer
Outer membrane of gram negative bacteria. 1. Polysaccharid portion has two components : O antigen and Core Polysaccharide2. Lipid portion called Lipid A : fatty acids connected to amine group
Lipid A of LPS
Causes inflamation when immune system kills bacteria
How many carbons are in Core Polysaccharide of LPS?
7 (this is odd)
Outer membrane has a lot of porins for movement of small hydrophilic molecules
(2 types)
1. Non-specific : Water filled2. Specific : Have binding site for specific substance
Slime Layer
Loosely associated layer
Capsule
Tightly associated amino acid polymer. Usually associated with disease causing 1. Protects from dessication 2. Adherence to cells via biofilms 3. Prevention of phagocytosis
Bacterial DNA
(location and binding proteins)
Found in nucleoid. No histones, but have binding proteins. Circular chromosome.
Plasmids
(Shape and function)
Small circular DNA. Don't usually have necessary genes, but have genes that give selective advantage in various environments.
Drugs ending in -mycin
Target bacterial ribosomes. Archaeal ribosomes are not effected. They are too similar to eukaryotes.
Thylakoid Membranes
Phototrophs have these. They are folds in plasma membrane that function in the light reactions of photosynthesis.
Carboxisomes
Surrounded by a protein membrane. Contain rubisco which is used for affixing CO2
Gas Vessicles
Protein coat that is permeable to gases, but not liquid. They are used for buoyancy in photosynthetic bacteria
Enterosomes
Found in intestinal (enteric) bacteria Metabolize enzymes in the intestine
Pilli
Usually found on gram negative bacteria Involved in conjugation Made of pillin Bind viruses Motility
Composed of flagellin Hook- Wide region at base of filament. Connects filament to motor portion of base. Motor- Central rod that passes through series of rings. L Ring- Gram neg : Anchored to LPS layerP Ring- Peptidoglycan layer MS & C Rings- Cytoplasmic Membrane and cytoplasm Mot Proteins- Generate torque Fli Proteins- Motor switch, reverses direction
How Flagella Works
Rotor : Central rod, L, P, C, and MS Rings- together called the Basal BodyStator : Mot Proteins surrounding basal body
Proton movement through Mot Proteins drives rotation.
Fimbriae
Shorter than flagella. Used for cell to adhere to surfaces
Vocab:
1. Single Flagella
2. Single Flagella at Each Pole
3. Tuft of Flagella at One or Both Ends
4. Evenly Distributed Flagella All Over Surface
1. Monotrichous 2. Amphitrouchous 3. Lophotrichous 4. Peritrichous
Chemotaxis
Drawn toward chemicals of food or other bacteria 1. Spacial Gradient- Conc. of chem in space 2. Temporal Gradient- Is conc. increasing or decreasing
Phototaxis
Drawn toward light
Antigens on bacterial surface (3)
H Antigen- Flagellar antigen O Antigen- LPS K Antigen- Capsular antigen
Endospores
Produced in detrimental environment Resist heat, chemicals, radiation
Cycle of Spore Formation
Vegetative Cell -> Sporulating Cell -> Mature Spore -> Germination (repeat)
Seven Stages of Endospore Formation
1. DNA becomes dense 2. Asymetric Cell Division 3. Endospore septum grows around protoplast 4. Forespore formation, Primordial cortex formed between two membranes, dehydration 5. Calcium incorporation, dehydration, coat layers formed 6. Maturation (development of heat resistant chemicals) 7. Lysis of cell and release of endospore
4 Properties of Viruses
1. Infectious 2. Must use host to manufacture components 3. Genome codes for proteins host can't provide 4. Self assemble
Capsid
(virus)
Protein case, arranged in precise repetitive order
Capsomer
Larger capsid. More elaborate with more types of proteins. Smallest thing to be seen with an electron microscope
Nucleocapsid
Complete package of nucleic acids and proteins
Icosahedron
20 faces, 12 vertices Most efficient arrangement of subunits
Lysozyme
Enzyme carried by virus to produce hole in cell wall to enter or lyse
Reverse Transcriptase
Carried by retroviruses to convert RNA into DNA
Titer
Measure of virus quantity
Plaque Assay
Each plaque is from a single virion Plaque- cleared area of plate
5 Steps of Virus Replication
1. Attachment (Absorption) into host 2. Penetration (entry, injection) of virion or genome 3. Synthesis- of viral nucleic acid and proteins 4. Assembly- of capsids and pachaging of viral genomes (maturation) 5. Release- of mature virions from cell
Latent Period
Eclipse + Maturation
Eclipse- When viruses attach to host and are unable to affect other cells Maturation- Titer increases as new viruses are formed, but they are trapped in host cell
Burst Size
Number of viruses released from host
Attachment
(virus)
Attach to specific receptor of host
What does it mean that a cell is "permissive to a virus"?
Cell allowed viral genome to enter
Restriction Endonucleases
How do they defend cell? How do viruses get around this?
Destroy double strand viral DNA after it enters. Virus can use glucosylation or methylation to mark DNA for protection from restriction enzymes. Virus can also encode proteins to inhibit restriction system.
Seven Classes of Viruses
1. dsDNA 2. ssDNA 3. dsRNA 4. ssRNA + 5. ssRNA - 6. ssRNA w/ DNA intermediate 7. dsDNA w/ RNA intermediate
Shapes of Viruses & Examples
1. Helical (Tobacco mosaic virus) 2. Polyhedral (Adenoviruses) 3. Spherical (Influenza) 4. Bacteriophage (T4)
Naked Virus vs Enveloped Virus
Naked : NucleocapsidEnveloped : Nucleocapsid inside envelope
Early Proteins
Synthesized soon after infection Necessary for replication of virus nucleic acids (poymerases) Typically act catalytically Synthesized in smaller amounts
Late Proteins
Synthesized later in infection Include proteins of virus coat Typically structural components Synthesized in larger amounts
Retrovirus Structure and Function
Retrovirus Genome
Two identical ssRNA+ molecules gag gene : structural proteinspol gene : reverse transcriptase and integraseenv gene : encode envelope proteins
Animal RNA Viruses
Nonenveloped:
Enveloped:
Nonenveloped : ssRNA, dsRNAEnveloped : ssRNA only
Effects of Virus on Animal Cell (5)
1. Cell fusion 2. Virus present but not replicating=lysis 3. Slow release of virus w/o cell death 4. Lysis 5. Tumor Cell
Prion
abnormal protein with a lot of beta sheets. transmissible spongiform encephatopathies (TSE) Turns other proteins abnormal Mad Cow Disease
Generation Time aka Doubling Time
Time it takes for bacteria to reproduce
Graph (log of viable cells)
Lag Phase
Exponential growth phase
Downslope
Lag Phase- small slow. Bacteria still getting used to medium Exponential growth phase- When generation time is measured. Keep growing until resources run out Downslope- bacteria consume eachother (cell walls)
Spread Plate Method vs Pour Plate Method
Spread plate- hockey stick to spread on medium Pour plate- bacteria diluted and poured along with medium
Common errors in viable cell counts
1. Innoculation size 2. Culture medium 3. Incubation conditions and length
Turbidity
Cells reflect light turbidity is proportional to the number of cells
Continuous Culture
Chemostat
Steady state. Cell number and nutrient status remain constant.
Chemostat adds medium, air, and removes dead cells
Growth Yield
Concentration of nutrient in limiting amount
Factors Influencing Microbial Growth
Macronutrients
Micronutrients
Siderophores
Macronutrients- Carbon, nitrogen, water, etc. (need a lot) Micronutrients- cofactors and growth factors (need a little) Siderophores excreted to obtain iron
Microbial nutrition chart
Categorized by energy source and carbon source
Chemicall defined media vs Chemically undefined media
Chemically defined- precise amount of purified chemicals and distilled water Chemically undefined- protein and amino acid based (better)
Selective Medium
Allows growth of some organisms and inhibits others
Differential medium
Identify organism by biochemical difference between two organisms that grow equally well on certain medium
Enriched Medium
Add nutrients that allow organism to grow that wouldn't normally ex. bile and crystal violet- selects for gram negative ex. lactose fermentation- select for organism that ferments lactose. Read with pH meter
Temperature Extremophiles
Psychorophile - 4 Mesophile- 39 Thermophile- 60 Hyperthermophile- 106
Obligate Aerobe
Needs oxygen
Obligate anaerobes
Die in oxygen environement
Facultative Anaerobes
Use oxygen and other electron acceptor. Can survive in oxygen but doesn't need it
Microaerophilic
Require low oxygen levels
Aerotolerant anaerobes
Don't use oxygen but aren't killed by it
Sodium thioglycolate
Used to reduce oxygen in lab. Gives layers in broth of varied oxygen concentrations
Aerobes vs Anaerobes in flast
Lab setting
Aerobes: 1. Vigorously shake flask 2. Bubbling sterilized air 3. Large headspace
Anaerobes 1. Fill tube so no headspace 2. Reducing agent (reduce O2 to H2O) ex. thiogycolate
Acidophile Nomenclature
Adaptations of acidophiles & alkaliphiles
Obligate- Needs acidic environment Tolerant- will survive in acid but doesn't prefer
Acidophiles- adapt membrane stability under high proton concentration
Alkaliphiles- adapt Na+ gradient instead of H+ gradient
Halophiles
Osmophiles
Xerophiles
Halophiles- salt Osmophiles- sugar Xerophiles- dry environment
To maintain osmolarity in salty environment
1. pump inorganic ions 2. increase synthesis of organic solute (Compatable solutes= don't inhibit biochemistry or cell processes)
Bacteriocidal
Bacteriostatic
Decontamination
Disinfection
Sterilization
Bacteriocidal- kill bacteria Bacteriostatic- inhibit growth of bacteria Decontamination- treatment to make inanimate surface safe to handle Disinfection- Eliminate all pathogens, but not all microbes Sterilization- Eliminate all microbes
Physical Antimicrobial Control (3 methods)
1. Heat- high temp for long time to get microbe and endospores 2. Radiation 3. Filtration
Autoclave
Used to sterilize. use steam heat pressure at temp above boiling point
Thermal Death Times
Time it takes to kill cells at certain temp
Decimal Reduction Time
Time required for ten-fold reduction of population density at a given temperature
Electromagnetic Radiation (3 methods to control microbial growth)
1. UV radiation- decontaminate air and water 2. Ionizing radiation- penetrate light absorbing materials and break DNA 3. heat
Best filter size
0.2um filter Used especially for heat sensitive mediums (mediums that can't be heated) HEPA filter traps bacteria
Which of the following statements about the intracellular state of a virus is NOT correct?
a) The virus particle is referred to as a
virion.
b) New copies of the virus genome are produced.
c) The virus replicates.
d)The components that make up the virus coat are synthesized.
a) The virus particle is referred to as a virion.
The smallest morphological unit of a virus that can be seen with the electron microscope is the:
A) capsomer.
B) viral nucleic acid.
C) capsid.
D) virus spikes.
A) capsomer.
Which of the following statements does NOT describe a factor affecting the efficiency of plating in quantitative virology?
A) The virus successfully infects a host cell and causes the formation of a plaque.
B) The viral mutation rate may be so high that many virions contain defective genomes.
C) Some virions do not successfully infect cells.
D) Some viruses produce many incomplete virus particles during infection.
A) The virus successfully infects a host cell and causes the formation of a plaque.
During the first few minutes after a virus infects a cell, the virus is said to undergo:
A) titer
B) attachment
C) entry
D) eclipse
D) eclipse
Restriction enzymes are specific for:
A) double-stranded RNA viruses.
B) single-stranded DNA viruses.
C) double-stranded DNA viruses.
D) single-stranded RNA viruses.
C) double-stranded DNA viruses.
What type of virus requires an enzyme known as reverse transcriptase?
A) bacterial viruses
B) smallpox virus
C) polioviruses
D) retroviruses
D) retroviruses
T4 DNA is protected from host defenses by glycosylation of:
A) thymine.
B) adenine.
C) cytosine.
D) guanine.
C) cytosine.
Which of the following viruses causes a latent infection?
A) P1
B) lambda
C) T4
D) herpes simplex virus
D) herpes simplex virus
During a retroviral infection, where is the RNA converted into DNA?
A) in the virus itself, before entry into the host cell
B) in the host cell's nucleus
C) in the cytoplasm associated with the endoplasmic reticulum
D) in the cytoplasm within an uncoated viral core particle
D) in the cytoplasm within an uncoated viral core particle
Viroids possess what type of nucleic acid?
A) single-stranded DNA
B) double-stranded RNA
C) single-stranded RNA
D) double-stranded DNA
C) single-stranded RNA
A prion particle contains:
A) DNA.
B) polysaccharide.
C) protein.
D) RNA.
C) protein.
Which of the following is NOT one of the three distinct mechanisms by which prion disease occurs?
A) endogenous prion disease
B) sporadic prion disease
C) inherited prion disease
D) infectious prion disease
A) endogenous prion disease
Which statement regarding the cytoplasmic membrane is NOT correct?
A) Hopanoids are present in the cytoplasmic membranes of many Bacteria and serve to strengthen and stabilize the membrane.
B) The cytoplasmic membrane is a highly fluid structure in which proteins are free to move among the phospholipids.
C) The general structure of the cytoplasmic membrane is a phospholipid bilayer.
D) The inner surface of the cytoplasmic membrane interacts with proteins involved in energy-yielding reactions.
B) The cytoplasmic membrane is a highly fluid structure in which proteins are free to move among the phospholipids.
In a peritrichous arrangement of flagella, how are the flagella distributed over the organism?
A) Multiple flagella are randomly dispersed over the cell surface.
B) Multiple flagella are attached to one end of the cell.
C) A single flagellum is attached at one end of the cell.
D) A single flagellum is attached at both ends of the cell.
A) Multiple flagella are randomly dispersed over the cell surface.
ABC System refers to:
A) the ATP-binding cassette.
B) a means of passive uptake of nutrients.
C) the generation of the high-energy compound ATP.
D) a means of locomotion in bacteria.
A) the ATP-binding cassette.
The outer portion of the outer membrane is, for the most part, composed of:
A) lipopolysaccharide.
B) teichoic acids.
C) phospholipids.
D) lipid A.
A) lipopolysaccharide.
Which cell surface structure can also be used as a receptor by certain viruses?
A) flagella
B) slime layer
C) capsule
D) pili
D) pili
Which of the following statements regarding the cell wall of bacteria is NOT correct?
A) The composition of the amino acids in the tetrapeptide and interbridge can vary.
B) It helps to provide shape and rigidity to the cell.
C) It is composed of a repeating framework of lipids.
D) It is a target of certain antibiotics.
C) It is composed of a repeating framework of lipids.
The outermost layer of the outer membrane is composed of:
A) glycerol polymers.
B) teichoic acids.
C) lipopolysaccharide.
D) periplasm.
C) lipopolysaccharide.
Species of the Euryarchaeota include all the following EXCEPT:
A) methanogens.
B) hyperthermophiles.
C) extreme halophiles.
D) photoautotrophs.
D) photoautotrophs.
What is always a product of a methanogenic reaction?
A) CO2
B) CH4
C) HCO3-
D) H2O
B) CH4
Where does oxidative phosphorylation take place within an aerobic eukaryote?
A) the hydrogenosome
B) the nucleus
C) the mitochondrion
D) the chloroplast
C) the mitochondrion
hloroplasts are found in all the following organisms EXCEPT:
A) certain protists.
B) unicellular and multicellular algae.
C) plants.
D) photosynthetic prokaryotes.
D) photosynthetic prokaryotes.
Where in a eukaryotic cell are 70S ribosomes found?
A) They are found within the cytoplasm of a eukaryotic cell.
B) They are found within the nucleus of a eukaryotic cell.
C) There are no 70S ribosomes found in a eukaryotic cell.
D) They are found within the mitochondria of a eukaryotic cell.
D) They are found within the mitochondria of a eukaryotic cell.
The energy to drive motility in
motile eukaryotes is derived from a protein called ________, which is
attached to tubulin and functions as an ATPase.
A) dynein
B) axoneme
C) integrin
D) ECM
A) dynein
Which of the following protists are animal parasites?
A) euglenids
B) apicomplexans
C) dinoflagellates
D) ciliates
B) apicomplexans
To obtain iron, some bacteria produce phenolic siderophores called:
A) ferrobactin.
B) aquachelin.
C) enterobactin
D) cytochelin.
C) enterobactin
In oxidative phosphorylation, ATP is produced:
at the expense of the proton motive force.
Chemolithotrophs use what compound as a carbon source?
A) an inorganic compound
B) sunlight
C) an organic compound
D) carbon dioxide
D) carbon dioxide
Under which of the following conditions would a lag phase NOT occur?
A) An inoculum of damaged cells is transferred into the same medium.
B) A microbial population is transferred from a rich culture medium to a poorer one.
C) An exponentially growing culture is transferred into the same medium under the same conditions of growth.
D) An inoculum is taken from a stationary-phase culture and transferred into the same medium.
C) An exponentially growing culture is transferred into the same medium under the same conditions of growth.
The most important environmental factor affecting the growth and survival of microorganisms is:
A) oxygen.
B) temperature.
C) water availability.
D) pH.
B) temperature.
Organisms capable of causing disease in humans and animals are of which temperature class?
A) thermophiles
B) mesophiles
C) psychrophiles
D) hyperthermophiles
B) mesophiles
Which of the following statements about thermophiles/hyperthermophiles is NOT correct?
A) The amino acid sequence of their enzymes differ greatly from those of the heat-sensitive forms of the enzymes that catalyze the same reaction in mesophiles.
B) Certain solutes, such as di-inositol phosphate and mannosylglycerate, are
C) Cytoplasmic membranes have membrane lipids rich in saturated fatty acids.
produced at high levels and help to stabilize proteins.
d) Their proteins have an increased number of ionic bonds between basic and acidic amino acids and their often highly hydrophobic interiors.
A) The amino acid sequence of their enzymes differ greatly from those of the heat-sensitive forms of the enzymes that catalyze the same reaction in mesophiles.
In which habitat would you expect to find aerobic prokaryotes?
A) sewage sludge
B) the ocean surfaces
C) mud and other sediments
D) the deep subsurface of the earth
B) the ocean surfaces
To live in the presence of oxygen, an organism must possess:
A) highly hydrophobic proteins and saturated fatty acids in the cytoplasmic membrane.
B) transpeptidase and peroxidase.
C) superoxide and catalase.
D) superoxide dismutase and either catalase or peroxidase
D) superoxide dismutase and either catalase or peroxidase