Exam 1 Flashcards
Staphylo-
Clustered
cocci
Spherical
Koch’s postulates
- The same pathogen must be present in every case of the disease
- The pathogen must be isolated from the diseased host and grown in pure culture
- The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal
- The pathogen must be isolated from the inoculated animal and must be shown to be the orginal organism
Treatment with chemical is ______
chemotherapy
Chemotherapeutic agents used to treat infectious disease can be _____ drugs or antibiotics
Synthetic
_____ are chemicals produced by bacteria and fungi that inhibit or kill other microbes
antibiotics
Pleomorphic
multiple shapes
monomorphic
one shape
Spirillum
one or more twists
Vibrio
Curved rod
Spirochete
Flexible, helical spirals
Strepto-
Chains
Diplo-
pairs
Smaller cells have a _____ suface area/volume ratio
larger
An inclusion that provides buoyancy for floating in aquatic enviroments
Gas Vacuole
_____ is an absolute requirments for all living organims
Plasma Membrane
Bacterial membranes lack ____
sterols (but can contain hopanoids, which are a sterol-like molecule)
Homologs of all ___ eukaryotic cytoskeletal elements have been identified in bacteria
3
FtsZ
- (many bacteria)
- Forms ring during septum formation in cell division
MreB
- Found in bacilli, not cocci
- Maintains shape but by positioning peptidoglycan synthesis machinery
CreS
- rare, maintains curve shape
Plasma membrane infolding is observed in
- many photosynthetic bacteria
- many bacteria with high respiratory activity
Types of Inclusions
- Storage
- Gas Vacuoles
- Magnetosomes
Magnetosomes
- found in aquatic bacteria
- magnetitie particles (iron) or orientation in Earth’s magnetic field
- Cytoskeletal protein MamK
- helps form magnetosome chain
bactrial and archaea ribosome
70S
Eukaryotic ribosome
80S
Bacterial ribosome RNA
- 16S small subunit
- 23S and 5S in large subunit
plasmids
- Extrachromosomal DNA
- found in bacteria, arachaea, and some fungi
- usually small, closed circular DNA molecules
- Exist and replicate independently of chromosome
- episomes- may integrate into chromosome
- inherited during cell division
- Contain few genes that are non-essential
- Confer selective advantage to host (e.g. drug resistance)
- Classification based on mode of existence, spread, and function
Function of conjugative plasmids
- Transfer of DNA from one cell to another
R plasmids
- Carry antibiotic-resistance genes
functions of Cell wall
- Maintains shape of the bacterium
- Almost all bacteria have one
- Helps protect cell form osmotic lysis
- Helps protect from toxic materials
- May contribute to pathogenicity
Chains of peptidoglycan subunits are joined by ____ (covalent bonds) between the peptides
cross-links
Meshlike polymer of identical subunits forming long strands
- Two alternating sugars
- N-acetylglucosamine (NAG)
- N-acetylmuramic acid
- Alternating D- and L- amino acids (this is hooked on the NAM)
- ends in D-alanine
Fucntions of teichoic acids
- help maintain cell envelope
- protect from environmental substances
- May bind to host cells
Periplasmic space of gram positive bacteria
- Lies between plasma membrane and cell wall and is smaller than that of Gram-negative bacteria
- Periplasm has relatively few proteins
- Enzymes secreted by Gram-positive bacterai are called exoenzymes
- aid in degradation of large nutrients
What are enzymes secreted by Gram-positive bacteria called
exoenzymes
Outer membrane of gram negative cells is composed of
- Lipids
- lipoproteins
- lipopolysaccharide (LPS)
_____ connect outer membrane to peptidoglycan in gram negative cell wall
Braun’s Lipoproteins
Lipopolysaccharide (LPS)
- Lipid A (endotoxin)
- Core polysaccharide
- O side chain (O antigen)
Lipid A is embedded in the ______ while core polysaccharide O antigen chain ______
outer membrane, extend out from the cell
Importance of LPS
- Contributes to negative charge on cellsurface
- Helps stabilize outer membrane structure
- may contribute to attachment to surfaces and biofilm formation
- Creates a permeability barrier
- Protection from host defenses (O antigen)
- Can act as an endotoxin (lipid A)
The outer membrane of gram-negative bacteria is more permable due to
the presence of porin proteins and transporter proteins
Lysozyme breaks the bond between ______ and _______
N-acetyl glucosamine and N-acetylmuramic acid
Penicillin inhibits ______
peptidoglycan synthesis
What cells that loss a cell wall may survive in Isotonic environments
- Protoplasts
- Spheroplasts
- Mycoplasma
- Does not produce a cell wall
- Plasma membrane more resistance to osmotic pressure
Archeal cell walls lack peptidoglycan but some have ______, also called ____
Pseudopeptidoglycan, pseudomurein
Components outside of the cell wall
- Outermost layer in the cell envelope
- glycocalyx
- Capsules and slime layers
- S layers
- Aid in attachment to solid surfaces
- e.g. Biofilms in plant and animals
Capsules usually are composed of
- polysaccharides
What are the protective advantages of capsules
- resistant to phagocytosis
- protect from desiccation
- exclude viruses and detergents
Slime layers
- Similar to capsule except diffuse, unorganized and easily removed
- slime may aid in motility
S layers
- Regularly structured layers of protein or glycoprotein that self-assemble
- in gram-negative bacteria the S layer adheres to outer membrane
- in gram-positive bacteria it is associated with the peptidoglycan surface
S layer functions
- Protect from ion and pH fluctuations, osmotic stress, enzymes, and predation
- Maintains shape and rigidity
- Promotes adhesion to surfaces
- Protects from host defenses
- Potential use in nanotechnology
- S layer spontaneoulsy associates
functions of flagella
- Motility and swarming behavior
- Attachment to surfaces
- may be virulence factors
What are the three components of the flagella
- Filament
- extends from cell surface to the tip
- hollow, rigid cylinder of flagellin protein
- Hook
- links filament to basal body
- Basal Body
- Series of rings that drive flagellar motor