Module 2 - Bacterial Morphology and Taxonomy Flashcards
How big are most eukaryotic cells?
Bigger than 5 um
How big are most bacterial cells?
0.5 - 5 um in length
How big are most viruses?
Less than 0.5 um
Rank the following in size order: viruses, eukaryotic cells, bactera
Viruses < bacteria < eukaryotic cells
What size can the naked eye see up to?
Up to 100 um
What is used to visualize bacterial cells?
The light microscope
What is the smallest bacterium discovered?
Mycoplasma gallicepticum
What is special about Mycoplasma gallicepticum?
It is the smallest bacterium discovered
What is the largest bacterium discovered?
Thiomargarita namibiensis
What is special about Thiomargarita namibiensis?
It is the largest bacterium discovered
True or false: Mycoplasma gallicepticum have a cell wall
False: they do not have a cell wall
How come most antibiotics don’t work on Mycoplasma gallicepticum?
Most antibiotics target cell wall synthesis, but M. gallicepticum does not have a cell wall
True or false: Mycoplasma gallicepticum is parasidic
True: it can cause disease
Where can Mycoplasma gallicepticum be found when infecting a host?
The genital, respiratory, or bladder track
How large is Thiomargarita namibiensis?
100-300 um, with some as large as 750 um
What was Thiomargarita namibiensis named after?
The continental shelf of Namibia (where they were discovered in ocean sediments)
What does coccus mean?
Spherical
What is a spherical bacteria called?
Coccus
What dos bacillus mean?
Rod-shaped
What is a rod-shaped bacteria called?
Bacillus
What does vibrio mean?
Curved rods
What is a curved bacteria called?
Vibrio
What does spirilla mean?
Spiral
What is a sprial bacteria called?
Spirilla
What does pleiomorphic mean?
Varied shapes
What is a varied-shaped bacteria called?
Pleiomorphic
What can you say about the size of pleiomorphic bacteria?
Tend to be smaller than other bacteria
True or false: bacteria can organize into “multicellular” organisms
True: this organization can be seen in some bacteria
What are hyphae?
Branching filaments of cells
What are mycelia?
Tufts of hyphae
What are trichomes?
Smooth, unbranched chains of cells
What is an example of a bacteria that organizes into mycelia?
Cyanobacteria
What is special about Cyanobacteria?
They form mycelia filaments
What is an example of a bacteria that organizes into trichomes?
Myxobacteria
What is special about Myxobacteria?
They form trichomes
How do cyanobacteria create mycelia filaments?
They adhere through a common cell wall
What do Myxobacteria do (where they live)?
Feed on inorganic substances in the soil
What can be said about the genome of Myxobacteria?
It is relatively large
What shape is E. coli?
Bacillus
What shape is Treponema pallidum?
Spirilla
True or false: bacteria have ribosomes
True
True or false: all bacteria have a cell wall
False: most, but not all, bacteria have a cell wall
Where is cytoplasm found?
Between the nuclear region and the plasma membrane of the cell
What is the appearance of cytoplasm?
Gel like
What is the composition of cytoplasm?
80% water, 20% proteins/lipids/carbs/inorganic ions
What do protein filaments do?
Lead to rod or spherical shaped bacteria
What do ribosomes do?
Produce proteins
What are ribosomes composed of?
rRNA and proteins
What is a plasmid?
DNA separate from the chromosomal genes, and can replicate independently
What is the appearance of a plasmid?
Small, circular double stranded DNA
What occupies a big portion of the bacterial cytoplasm?
The nucleoid region
What is the nucleoid region?
The area with chromosomal DNA and replication machinery
What is the structure of a typical bacterial chromosome?
A singular, circular DNA strand
How can chromosomes vary from the typical structure?
Some bacteria have linear chromosomes, and some have more than one chromosome
What is another name for inclusion bodies?
Elementary bodies
What are inclusion bodies?
Cytoplasmic aggregates of stable substances (usually proteins)
What happens at inclusion bodies?
They are a site for viral replication, and contains capsid proteins
What are some examples of inclusion bodies?
Polyhydroxybutyrate granules, and sulfur globules
What happens at polyhydroxybutyrate granules?
Carbon storage
Which part of the bacteria acts in carbon storage?
Polyhydroxybutyrate granules
What happens at sulfur globules?
Sulfur storage
Which part of the bacteria acts in sulfur storage?
Sulfur globules
What is another name for gas vesicles?
Gas vacuoles
What are gas vesicles composed of?
Proteins
What is the structure of a gas vesicle?
A hollow, cylindrical tube closed by conical end caps
What is the purpose of gas vesicles?
Regulate position in water in response to light or nutrients
Where are gas vesicles usually found?
In planktonic organisms
How come gas vesicles are usually found in planktonic organisms?
Buoyancy control is crucial for these organisms
What are carboxysomes?
Polyhedral protein shells with RuBisCo
What does RuBisCo stand for?
Ribulose bisphosphate carboxylase
What do carboxysomes do?
Function in carbon fixation and the calvin cycle
What are magnetotactic bacteria?
Gram-negative bacteria that build magnetosomes
What is the structure of a magnetosome?
A lipid membrane with magnetite crystals
What is the purpose of magnetosomes?
Direction finding
Where does the magnetosome lead to?
Microaerophilic (low O2) environments for growth
What is the cytoskeleton composed of?
Proteins
What does the cytoskeleton do?
Organize components of the cell
What are some examples of cytoskeletal proteins?
MreB, FtsZ, ParR, and ParM
What is MreB a homolog of?
Actin
What is the structure of MreB, and where is it found?
Helical bands next to the plasma membrane
What type of bacteria universally contain MreB?
Nonspherical bacteria
Which bacteria rarely contain MreB?
Cocci
What does FtsZ stand for?
Filamenting temperature-sensitive mutant Z
What does FtsZ do?
Aids in cell division of the bactera
What does MreB do?
Helps form the shape of nonspherical bacteria
What is the structure of FtsZ, and where is it found?
A ring near the septum (where the bacterium splits)
What is FtsZ a homolog of?
Tubulin
Which protein is a homolog of actin?
MreB
Which protein is a homolog of tubulin?
FtsZ
What do ParR and ParM aid in?
The segregation of plasmids
What is needed for plasmids to move to daughter cells after division?
A ParC DNA site, and the proteins ParR and ParM
What is the ParMRC system?
The combination of the ParC DNA site, and the proteins ParR and ParM
What does ParM do?
Directs plasmid movement
Which other protein is like ParM?
Actin
What does ParR do?
DNA binding adaptor protein (connects ParC to ParM)
How does ParM interact with ParR and ParC?
It finds the plasmid filaments and the ParR/ParC components, and pushes the plasmids to opposite poles
What binds to ParC?
ParR
What does ParR bind to?
ParC
What is ParC?
A DNA binding site for ParR
What do cytoplasmic protein filaments do?
Contribute to the structural integrity of the cell
True or false: all cells have a plasma mebrane
True: it is required to separate external from internal
What is the composition of the plasma membrane?
A phospholipid bilayer with embedded proteins
What are the two types of proteins associated with the plasma membrane?
Peripheral proteins and integral proteins
What do peripheral proteins do, and where are they found?
They do not enter the membrane, and are found attached to the phosphate heads or integral proteins
What do integral proteins do, and where are they found?
They function as transporters, channels, linkers, receptors, energy accumulators, and cell adhesion proteins. They are found embedded within the membrane
What component do some (but not all) bacterial plasma membranes contain?
Hopanoids
What is the structure of hopanoids?
Pentacyclic compounds that mimic hopane
What are hopanoids analogous to?
Cholesterol
What are the functions of hopanoids?
Influence mobility and rigidity of the cell membrane
What is the purpose of hopanoids?
Adjust the cell membrane to adapt to extreme environments
How does CO2 and O2 get through the plasma membrane?
Through simple diffusion
How does H2O get through the plasma membrane?
Through aquaporins
What is osmosis?
The diffusion of water from lower solute concentration to higher solute concentration
What are the consequences of osmosis?
The cell could shrink or swell
How does a bacterium control the consequences of osmosis?
Through the cell wall
What is facilitated diffusion?
Diffusion of a nutrient down its concentration gradient through a specific channel protein
True or false: facilitated diffusion requires energy
False: it does not require energy, since it is moving down the concentration gradient
What is active transport?
Movement of a nutrient up its concentration gradient
True or false: active transport requires energy
True: it requires energy, since it is moving up its concentration gradient
What types of nutrients are usually transported through active transport?
Amino acids, glucose, ions, etc.
What are the two types of active transport?
Primary active transport and secondary active transport
What is primary active transport?
Using ATP as the source of energy in active transport
What is secondary active transport?
Using an electrochemical gradient as the source of energy in active transport
What are the 2 primary active transporters mentioned in this lecture?
P-type ATPases, and ABC transporters
What transporters usually transports ions?
P-type ATPases
What do P-type ATPases usually transport?
Ions (sodium, potassium, calcium, proton, etc.)
What is the purpose of a P-type ATPase?
Maintain membrane potential
What is the net reaction of the sodium potassium pump?
One ATP is used to move 3 Na out, and 2 K in
What does ABC transporter stand for?
ATP binding cassette transporter
What are some examples of ABC transporters?
MDR, CFTR, etc.
What is the structure of an ABC transporter?
4 subunits (2 hydrophobic, 2 hydrophilic)
What do the hydrophobic subunits of the ABC transporter do?
Form the transmembrane channel
What do the hydrophilic subunits of the ABC transporter do?
ATP binding domain on cytosolic portion of the cell
What does the associated subunit of the ABC transporter do?
Binds to the solute with high affinity
How do ABC transporters work?
The binding of the associated subunit causes ATP subunits to hydrolyze ATP, leading to conformation change and movement across the membrane
What is another name for secondary active transport?
Coupled transport, or co-transport
How does secondary active transport work?
One chemical moves down its electrochemical gradient, while another chemical moves up its electrochemical gradient
What is a common ion used in secondary active transport?
Sodium
What are the two types of cotransporters?
Symporters and antiporters
What is a symporter?
The two substances move in the same direction
What is an antiporter?
The two substances move in the opposite direction
What is an example of an antiporter?
The sodium-calcium exchanger (NCX)
What is an example of a symporter?
The sodium-glucose transporter
What does NCX stand for?
Sodium-calcium exchanger
What is the net reaction of NCX?
3 sodium into the cell, 1 calcium out of the cell
How does the plasma membrane capture energy?
It contains components of the ETC to create a proton gradient across the membrane
What does PMF stand for?
Proton motive force
What is PMF used for?
Respiration, photosynthesis, and motion (flagella)
What do the sensory systems of the plasma membrane do?
Change gene expression to respond to the environment
What proteins are involved in the secretion pathway?
The Sec proteins
What does the SecB protein do?
Associates to newly synthesized polypeptides that need to be secreted from the cell
How does the SecB protein alter the polypeptide?
It prevents it from folding, and directs it to SecA
What does SecA do?
It associates with SecB and SecYEG to hydrolyze ATP and push the polypeptide out of the cell
What does SecYEG do?
Form a channel protein that can allow for the polypeptide do be secreted
Which Sec protein associates with the newly synthesized polypeptides?
SecB
Which Sec protein hydrolyzes ATP and pushes the polypeptide out of the cell?
SecA
Which Sec protein forms the channel?
SecYEG
What does the signal peptidase do?
Removes the signal peptide from the polypeptide
Where is the signal peptidase found?
In the periplasmic space
What happens after the signal peptide is cleaved from the polypeptide?
It can fold into its conformational (protein) shape
What percentage of bacteria have a cell wall?
90%
What is the purpose of the cell wall?
Provide structure, strength, and protection from mechanical/osmotic forces
What is the cell wall of plants made out of?
Cellulose
What is the cell wall of fungi made out of?
Chitin
What is the cell wall of bacteria made out of?
Peptidoglycans
What is the structure of the cell wall?
Peptidoglycan layers crosslinked together (similar to a chain-link fence)
What is another name for the peptidoglycan?
Murein
True or false: peptidoglycans play a role in binary fission
True: they are important in reproduction
What is the structure of a peptidoglycan?
Disaccharide composed of NAG and NAM, and a small peptide chain
What type of molecules are NAG and NAM?
Amino sugars
What does NAG stand for?
N-acetylglucosamine
What does NAM stand for?
N-acetylmuramic acid
What holds together NAG and NAM?
Beta 1-4 glycosidic bond (alternate)
Where is the peptide chain found in the peptidoglycan layers?
Only on the NAM subunits
True or false: only one end of the peptide chain is attached to NAM
False: both ends of the peptide chain are attached only to NAM
True or false: the peptide chains on NAM are conserved within bacteria
False: they vary from species to species
What forms the 3D mesh-like layer of the peptidoglycan layer?
Crosslinking between the peptide chains
What is used to crosslink the peptide chains?
D amino acids
True or false: the crosslinking peptides between NAM are conserved within bacteria
False: they vary from species to species
Where is the cell wall formed?
Outside of the plasma membrane
What is the function of bactoprenol?
Move the peptidoglycans across the cell membrane
What is the structure of bactoprenol?
An amphipathic lipid that spans the entire membrane
What are the precursors of NAM and NAG?
Glutamine and fructose-6-phosphate
What happens after NAM and NAG are formed in the cytoplasm?
NAG reacts with UTP to made UDP-NAG
What does UTP stand for?
Uridine triphosphate
What does UDP stand for?
Uridine diphosphate
What happens after UDP-NAG is produced?
It is converted into UDP-NAM-NAG
What happens after UDP-NAM-NAG is produced?
The small peptide chain is added
What is stage 1 of cell wall formation?
Forming the subunit peptidoglycans
What is stage 2 of cell wall formation?
Transporting the subunits across the cell membrane
How does bactoprenol interact with the subunits?
It joins through a pyrophosphate bond, thus linking the peptidoglycan sugars with bactoprenol
What happens once the NAG-NAM is linked to bactoprenol?
It flips to bring the subunits to the periplasm
What type of molecule is bactoprenol-NAM-NAG?
A lipid
What happens once the bactoprenol-NAM-NAG is at the periplasm?
The NAM-NAG is added to the growing peptidoglycan chain
What happens in the transglycosylation reaction?
It displaces the bactoprenol lipid from the NAM-NAG sugars, by linking the hydroxyl group of NAG to the NAM in the growing chain
What is the chemistry of the transglycosylation reaction?
The hydroxyl group of NAG links to NAM in the growing chain, displacing it from bactoprenol
What enzyme catalyzes the transglycosylation reaction?
Transglycosylase
What enzymes can degrade the cell wall?
Lysozyme and lysostaphin
What does lysozyme do?
It breaks beta-1,4-glycosidic bonds between peptidoglycans
True or false: lysozymes can work on all bacteria
True: it can work on many bacteria
How come lysozymes can work on many bacterial cell walls?
Beta-1,4-glycosidic bonds are found in many bacteria
What does lysostaphin do?
Breaks the crosslinking bridges composed of glycine between peptides
True or false: lysostaphin can work on all bacteria
False: it can only work on certain Staphylococcus species
How come lysostaphin can only work on certain Staphylococcus species?
The peptide crosslinking various between bacterial species
What are examples of Staphylococcus species?
MSSA and MRSA
What happens if bacteria do not have an intact cell wall?
Bacteria lose their shape, especially bacillus
What is a protoplast?
The spherical shape a Gram-positive bacillus bacteria makes when it has no cell wall
What is a spheroplast?
The spherical shape a Gram-negative bacillus bacteria makes when it has no cell wall
What is the danger of a protoplast?
They can be easily lysed in hypotonic conditions
What are beta-lactam antibiotics?
Antibiotics that contain a beta-lactam ring
What do beta-lactam antibiotics do?
They prevent the crosslinking of peptidoglycan layers, thus weakening the cell wall
What are some examples of beta-lactam antibiotics?
Penicillin, cephalosporin, carbapenem, amoxicillin, and monobactam
What does beta-lactamase do?
Breaks the beta-lactam ring in beta-lactam antibiotics
What is another name for beta-lactamase?
Penicillinase
What is the significance of beta-lactamase?
The antibiotic cannot inhibit the crosslinking, and thus the cell wall stays intact, and the bacterium survives
How can scientists overcome beta-lactamase?
Use a combination of a beta-lactam antibiotic, and a molecule that can inhibit beta-lactamase
What is an example of a combination drug designed to overcome beta-lactamase?
Augmentin
What is an example of a competitive inhibitor of beta-lactamase?
Clavulanic acid
How can bacteria be distinguished based on the cell wall?
Gram-positive and Gram-negative
What is the origin of the name Gram-positive and Gram-negative?
The reaction to the procedure developed by Christian Gram
What is the Gram-stain procedure?
- Cells are stained with crystal violet and iodine
- Cells are washed with an organic solvent
- Cells are stained with safranin
What is the purpose of the crystal violet dye in the Gram-staining technique?
It stains peptidoglycan purple
What is the purpose of the organic solvent in the Gram-staining technique?
It washes the crystal violet from certain bacteria
What is the purpose of the safranin in the Gram-staining technique?
It stains certain bacteria pink if they do not have crystal violet
What are the outcomes of the Gram-staining technique?
The bacteria will either look purple or pink
What does purple bacteria signify in the Gram-staining procedure?
Gram-positive bacteria
What does pink bacteria signify in the Gram-staining procedure?
Gram-negative bacteria
What leads to the different outcomes of the Gram-staining procedure?
Differences in the bacterial cell wall
What is the structure of a Gram-positive cell wall?
A thick layer of peptidoglycan (20-80 nm)
How thick is the peptidoglycan layer of Gram-positive bacteria?
20-80 nm
How much of the dry weight of Gram-positive bacteria is peptidoglycan?
90%
How large is the periplasmic space of Gram-positive bacteria?
Very narrow
What is the periplasmic space?
The space between the cell wall and the cell membrane in bacteria
Besides peptidoglycans, what are found in the cell wall of Gram-positive bacteria?
Teichoic acids
Where are teichoic acids found?
In Gram-positive bacteria
What is the structure of teichoic acids?
Negatively charged glycopolymers
Where are lipoteichoic acids found in the cell wall?
Linked to the membrane through glycolipids
Where are wall teichoic acids found in the cell wall?
Covalently linked to peptidoglycan
What is the function of teichoic acids?
Provide rigidity to the cell wall by attracting cations (sodium, magnesium, etc.)
What is the structure of a Gram-negative cell wall?
A thin layer of peptidoglycan, surrounded by another lipid membrane
What composes the outer membrane of Gram-negative bacteria?
Lipopolysaccharides and lipoproteins
How thick is the peptidoglycan layer of Gram-negative bacteria?
7-8 nm
How large is the periplasmic space in Gram-negative bacteria?
Larger than Gram-positive, but can still vary
How much of the dry weight of a Gram-negative bacteria is peptidoglycan?
10%
What is the structure of the outer membrane of Gram-negative bacteria?
A layer of phospholipids, and a layer of lipopolysaccharides
What does LPS stand for?
Lipopolysaccharides
What are the components of LPS?
Lipid A, core polysaccharide, and O side chain
What does O side chain stand for?
Outer side chain
What is the innermost region of LPS?
Lipid A
What is another name for Lipid A?
Endotoxin molecule
Wat does Lipid A do?
Anchors LPS to the outer membrane
How does Lipid A interact with humans?
It produces a strong inflammatory response
How can the O side chain interact with humans?
It can be changed by the microbe to evade host immunities
How do nutrients get through Gram-positive cell walls?
There are large pores in the peptidoglycan matrix
How do nutrients get through Gram-negative cell walls?
Through the porin and TonB proteins
What do the porin and TonB proteins do?
Allow nutrients to get through the Gram-negative cell wall
What does S-layer stand for?
Surface layer
Where is the S-layer (generally)?
Part of the cell envelope
How many organisms have an S-layer?
Many bacteria, and almost all archaea
What is the structure of the S-layer?
A monolayer of identical proteins or glycoproteins
What is the function of the S-layer?
Diverse: it varies from species to species (usually protection)
How is the S-layer attached in Gram-positive bacteria?
Attaches to peptidoglycan matrix through secondary cell wall polymers
How is the S-layer attached in Gram-negative bacteria?
It is closely associated with LPS of the outer membrane
What is one example function of the S-layer?
It may protect bacteria from bacteriophages or the immune system
What are bacteriophages?
Viruses that infect bacteria
What is a flagellum?
A lash or hair like appendage that protrudes from the cell body
How large is a flagellum?
15-20 nm in diameter
What is the primary function of the flagellum?
Motility or locomotion
What are the secondary functions of flagella?
Sensory organelle (sensitive to chemicals and temperature)
What defines flagella?
Function, not structure
What are polar flagella?
Flagella only at the ends of bacteria
What are monotrichous bacteria?
Bacteria with one flagellum at one end
If a bacterium has one flagellum at one end, what is it called?
Monotrichous
What are amphitrichous bacteria?
Bacteria with one flagellum at either end
If a bacterium has one flagellum at either end, what is it called?
Amphitrichous
What are lophotrichous bacteria?
Bacteria with multiple flagella at one end
If a bacterium has multiple flagella at one end, what is it called?
Lophotrichous
What are peritrichous bacteria?
Bacteria with multiple flagella all around the cell
If a bacterium has multiple flagella all around the cell, what is it called?
Peritrichous
What are axial filaments?
Flagella anchored at the periplasmic space (as opposed to the cell surface)
What species have axial filaments?
Some spirochetes
What is special about spirochetes?
They have axial filaments
What happens when axial filaments spin?
The whole cell spins like a corkscrew
Where does the energy to spin flagella come from?
The PMF
In bacteria, where is the proton pump machinery located?
On the plasma membrane
When happens when the flagella spin in one direction?
The bacterium moves in a straight line, and the flagella bunch together
What can you say about a bacterium moving in a straight line?
The flagella are spinning in one direction, bunched together
When happens when the flagella change their direction?
The bacterium tumbles, and the flagella come apart
What can you say about a bacterium that is tumbling?
The flagella are changing direction, spread apart
What are the three basic components of flagella?
A flagellar filament, hook, and basal body
What is the composition of the flagellar filament?
Flagellin protein
What does flagellin do?
Makes up the flagellar filament
How long is a normal flagellar filament?
5-10 um
Which is usually longer: the flagellar filament, or the cell?
The flagellar filament
What does the basal body do?
Anchors the flagellar filament to the cell envelope, and provides torque to the filament by interfacing with the motor
What is the structure of the basal body?
A disk-like structure
Where is the flagellar motor?
In the plasma membrane
What does the flagellar motor do?
Converts energy from PMF to drive rotation of the filament
What does the hook do?
Connects the filament to the basal body
What shape is the hook?
Curved
What interfaces with the flagellar motor?
The basal body
What is a pilus?
A hair-like appendage on the surface of many bacteria
What is the difference between pili and fimbriae?
Fimbriae are used for adhesion, while pili are used for conjugation
What is a sex pilus?
A pilus used for conjugation of plasmids
What is the composition of pili?
Pillin proteins
What does pillin do?
Subunit of pili
What is conjugation?
One bacterium donating one strand of its plasmid to another bacterium
What is another name for fimbriae?
Attachment pili
How do fimbriae compare to flagella?
Fimbriae are shorter and thinner than flagella
How come fimbriae are important for pathogenic bacteria?
Binding to the host target is an important first step in pathogenesis
What is another name for capsule?
K antigen
What are capsules composed of?
Polysaccharides
What type of bacteria have capsules?
Both Gram-positive and Gram-negative bacteria can have capsules
In what diseases is the capsule considered a major virulence factor?
Pneumonia and meningitis
What is the purpose of capsules?
Prevent bacteria from drying out, escape phagocytic action of host cells, and help form biofilms
What is the importance of biofilms?
Provide protection and enhanced survivability in harsh environments
True or false: all bacteria can be cultured
False: not all bacteria can be cultured
What is the order of taxonomy?
Domain –> kingdom –> phylum –> class –> order –> family –> genus –> species
What is a pneumonic for taxonomy?
King Philip Came Over For Good Spaghetti
What level is lower than species in taxonomy?
Strains
How is a bacteria named?
Through its genus and species
What is a genus?
A group of closely related species
What is a species?
A group of strains sharing common features, while differing considerable from other strains
What determines the shape of a bacterial cell?
The organization of the cell wall
In trichomes and mycelia, what are found in the partitions between cells?
Channels for intracellular passage of materials
What is needed to visualize viruses?
Electron microscopes
How do cations allow for DNA packing?
They positive charges can associated with negative DNA to pack it closer
What does topoisomerase do?
It is an enzyme that encourages the chromosome to coil upon itself
What is the purpose of topoisomerases?
Create supercoiling to pack the DNA
What does PHB stand for?
Polyhydroxybutyrate
What do PHBs do?
Act as a carbon storage
How can PHBs be used industrially?
They can be used as substitutes for plastics
What is the anammoxosome?
A compartment where ammonium is oxidized for energy
What does the Z-ring do?
It is formed by FtsZ proteins, and it aids in bacterial cell division. It also directs synthesis of the bacterial cell wall
How does the Z-ring constrict?
Through controlled release of FtsZ monomers through GTP hydrolysis
How does MreB work?
It guides the synthesis and formation of the cell wall into an elongated cylinder
What is the cell envelope?
The collection of the plasma membrane, cell wall, and outer membrane
What do cytochromes do?
Form the ETC
What is the sequence of the signal peptide?
A short sequence of large hydrophobic amino acids at the amino-terminal end of a polypeptide
How do mycoplasmas survive without a cell wall?
They live inside eukaryotic hosts
True or false: the cell wall is a permeability barrier
False: there is no selection to get through the cell wall
What is usually the first amino acid in the peptide on NAM?
L-Alanine (L-Ala)
What is usually the fourth and fifth amino acids in the peptide on NAM?
D-Alanine (D-Ala)
What happens to the fifth amino acid in the peptide on NAM?
It is removed when crosslinking occurs
In Gram-positive bacteria, what is usually the second amino acid in the peptide on NAM?
D-isoglutamine (D-GluNH2)
In Gram-negative bacteria, what is usually the second amino acid in the peptide on NAM?
D-isoglutamate (D-Glu)
What is usually the third amino acid in the peptide on NAM?
It varies greatly between species
What does transpeptidase do?
Crosslinks a pentapeptide precursor to the growing cell wall
What does the beta-lactam ring mimic?
D-Ala
True or false: beta-lactam antibiotics can target all cell walls
False: only cell walls that are currently growing can be affected by beta-lactam antibiotics
What is the composition of teichoic acids?
Ribitol phosphate or glycerol phosphate
What is the purpose of endospore formation?
It acts as a survival mechanism under stressful conditions
What are the characteristics of endospores?
Inert, and increased resistance to desiccation, UV light exposure, and high temperature
What is the composition of an endospore?
Additional layers of proteins outside of the peptidoglycan
What type of bacteria can create endospores?
Gram-positive bacteria
What is the purpose of oligosaccharides in the periplasm?
Help bacteria adjust to changes in osmolarity
What attaches the outer membrane to the cell wall?
Murein lipoprotein and peptidoglycan-associated lipoprotein
How does murein lipoprotein attach the outer membrane to the cell wall?
Links to the cell wall through carboxyl-terminal amino acid (lysine), and links to lipid chain through amino-terminal amino acid (cysteine)
What is the structure of porin?
Trimeric pores
What is the size limit of porins?
600 Da
How does TonB differ from porins?
TonB is better for scare nutrients
What proteins are found in complex with TonB?
ExbB and ExbD
Where does TonB get energy for active transport?
The proton motive force
What are autotransporters?
Proteins that can catalyze their own transit across the plasma membrane
What is the type III secretion pathway?
A “syringe” structure to cross the inner and outer membrane in one step
What is the type III secretion pathway related to?
Bacterial flagella
Which types of bacteria have the type III secretion pathway?
Gram-negative bacteria
How does the alcohol solvent interact with Gram-positive bacteria?
It strengthens the peptidoglycan matrix
How does the alcohol solvent interact with the Gram-negative bacteria?
It dissolves the outer membrane
What is chemotaxis?
The process of using chemical signals from the environment to direct motility
What controls if the flagella will all rotate in the same direction?
The cytoplasmic control system
What are chemoreceptors?
Receptors that detect attractants and repellants
What is special about Proteus mirabilis?
It can adapt to contact with surfaces by becoming hyper-flagellated
What is gliding motility?
Bacteria without flagella sliding smoothly over surfaces
What is twitching motility?
Relying on pili fibers to move along surfaces
True or false: all bacteria with pili can perform twitching motility
False: it is only inherent in certain pili bacteria
What is special about Shingella?
They move via the actin cytoskeleton within cells
What is a stalk?
A tubular extension of the entire cell envelope
What is the advantage of a stalk?
It increases the surface area to volume ratio, thus increasing nutrient uptake
What is a slime layer?
A less defined outer layer
What does glycocalyx refer to?
Both capsules and slime layers
How can an S-layer be lost?
If a cell does not need it anymore (such as in lab culture)
What is needed for each new taxon?
At least two different cultures of the bacteria in two different countries
What type of bacteria are part of Proteobacteria?
A wide range of Gram-negative bacteria, including human pathogens, nitrogen fixing bacteria, and photosynthetic bacteria
What is an example of a bacteria from Proteobacteria?
E. coli
Which phylum is mitochondria most closely related to?
Proteobacteria
What type of bacteria are part of Firmicutes?
A wide range of Gram-positive bacteria that have low GC content
What type of bacteria are part of Actinobacteria?
Gram-positive bacteria with high GC content
What are geosmins?
Organic compounds that have an aroma
What phylum produces geosmins?
Actinobacteria
What type of bacteria are part of Bacteroidetes?
Gram-negative bacteria that usually aid in digestion
What type of bacteria are part of Cyanobacteria?
Photosynthetic organisms
What are some bacterial phyla?
Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, and Cyanobacteria