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163 terms

Microbiology Chapter 3

STUDY
PLAY
1. Cytoplasm
2. Cytoplasmic Membrane
3. Nucleus (Ekuaryote) or Nucleoid (Prokaryote)
4. Ribsomes
5. Cell Wall
Basic Cellular Structures
Ribosomes
Used in protein synthesis and are NOT organelles
Prokaryote and Eukaryote
Two types of cells
Prokaryote
Simpler internal structure and lack membrane-enclosed organelles
Bacteria and Archaea
Examples of Prokaryotes
Eukaryote
Larger, more complex and have membrane-enclosed organelles
Algae, Fungi, Protozoa, Animals
Examples of Eukaryotes
Viruses
Non-cellular, reproduce only inside of a host cell, and lack many characteristics of living things
What virus causes colds?
Rhinoviruses
What virus causes rabies?
Rhabdovirus
In a bacterial cell, the cytoplasm is surrounded by this lipid membrane boundry
Envelope
What contains DNA in the cytoplasm of a Bacterial Cell?
Nucleoid
Cytoplasmic Membrane
"Fluid" selective permeability barrier made of phospholipids and proteins that form a bilayer with a hydrophillic exterior and hydrophobic interior
"Leaflet"
Each layer in the phospholipid bilayer of the cytoplasmic membrane is called a?
Phospholipid
Glycerol with ester links to 2 fatty acids
Hydrophilic
Group that faces the cytoplasm or periplasm
(dissolve in water)
Hydrophobic
Fatty acids lined up inside the membrane
(don't dissolve in water)
Selective Permeability
The result of the attraction of nonpolar fatty acid portions of one phospholipid layer for other layer
Integral Membrane Proteins
These span the cytoplasmic membrane
Peripheral Membrane Proteins
These are bound to the surface of the cytoplasmic membrane
1. Permeability Barrier
2. Structural Support
3. Energy Conservation
Functions of the Cytoplasmic Membrane
Permeability Barrier
Prevents leakage of cytoplasmic metabolites into the environment and transportation of substances (nutrients and waste products) into and out of the cell
Water and small, uncharged particles
What are the only things that can freely diffuse through the membrane due to the hydrophilic outside and hydrophobic inside?
Structural Support
Site of many proteins involved in transport, bioenergetics and chemotaxis
Energy Conservation
Site of generation and use of the protein motive force
Mitochondria
Generates energy by respiration in eukaryotes
Cytoplasmic Membrane
Where does respiration occur in prokaryotes?
Respiration and Photosynthesis
Two forms of energy conservation
Chloroplasts
Photosynthetic eukaryotes carry out photosynthesis here
Cytoplasmic Membrane
Photosynthetic prokaryotes carry out photosynthesis here
Sterols
What do eukaryotes use to reinforce their cytoplasmic membrane?
Cholesterol
What is an example of a sterol?
Hopanoids
What do Bacteria use to reinforce their cytoplasmic membrane?
Terpanoids
What do Archaea use to reinforce their cytoplasmic membrane by increasing the stability at high temperatures and low pH?
Peptidoglycan (murein)
A porous cage-like structure that makes up the bacterial cell wall.
Sacculus
The bacterial cell wall
N-acetylglucosamine (NAG) and N-acytelmuramic acid (NAM)
Two sugars that make up the backbone of peptidoglycan
Crosslinks
Short chains of amino acids that hold the sugars together
Meso-Diaminopimelate (mDAP)
Unusual amino acid found in the crosslinks of Gram negative bacteria
Provides rigidity and shape to the cell and prevents it from exploding due to high pressure inside the cell
Function of Peptidoglycan
Antibiotics
Since peptidoglycan is unique to bacteria, what is it a great target for?
Transpeptidase
What does Penicillin inhibit that is the crosslink for the peptides?
Beta-lactamase
This is produced by many organisms and it cleaves the lactam ring of penicillin, inactivating the penicillin
Archaea
Lack peptidoglycan so their cell walls are made of other polysaccharides such as pseudopeptidoglycan, have a paracrystalline surface layer cell wall, or have S-layers
Gram-Negative Bacteria
Only have a few layers of peptidoglycan--thin
Gram-Positive Bacteria
Have many layers (up to 40) of peptidoglycan
Teichoic Acids
The cell walls of Gram-positive Bacteria are reinforced by these negatively charged acids
L-lysine
The crosslinks within peptidoglycan of Gram-positive bacteria contain this
Lysozyme
Enzyme that destroys peptidoglycan, leading to cell lysis
Lysozyme
What is found in animal secretions and is thought to be major line of defense against infections by bacteria?
Outer lipopolysaccharide (LPS) layer and inner phospholipid layer
What makes up the lipid bilayer of a Gram-Negative bacteria?
Proteins (porins)
These are found within the membrane of a Gram-negative bacteria and are used in transport
Endotoxin--lipid A
Toxic portion of the lipopolysacchardie (LPS) layer of the Gram-negative bacteria. It has a toxic effect on humans and is released when the cell dies
Porins
Transmembrane proteins that allow for permeability through the outer membrane by creating channels that cross the membrane
Non-specific Porins
Water-filled channels through which small substances can pass
Specific Porins
Channels with binding sites for certain molecules that only allow those molecules to pass through
Periplasm
Space between the outer and cytoplasmic membrane of a Gram-negative Bacteria
Hydrolytic enzymes and Nutrient Transporter Binding proteins
Proteins that are contained in the periplasm of a Gram-negative Bacteria
Capsule, S layer, Thick Cell wall, Thin Periplasm, and Cytoplasmic Membrane
The Gram-Positive Envelope from the outside in contains:
Capsule
Part of the Gram-positive and Gram-negative envelopes that is made of a polysaccharide; not all species have it
S Layer
Part of the Gram-positive envelope that is made of proteins
Thick Cell Wall
Part of the Gram-positive envelope that is made of amino acids crosslinks in peptidoglycan. Contains Techoic acids for strength
Capsule, Outer Membrane, Thin Cell Wall, Thick Periplasm, and Cytoplasmic Membrane
The Gram-negative envelope from the outside in contains:
Outer Membrane
Part of the Gram-negative envelope that is made of lipopolysacchardies
Thin Cell Wall
Part of the Gram-negative envelope that is made of amino acid crosslinks in peptidoglycan
Genome
A cell's complete set of genes
Chromosomes
What is DNA arranged to form?
Plasmids
Prokaryotes have a singular circular chromosome and sometimes circular extrachromosomal DNA called
Several Linear
Eukaryotes contain chromosomes.
Nucleus
Membrane-enclosed structure found in eukaryotes that contains the chromosomes
Nucleoid
Mass of DNA found in prokaryotes that is not bound by a membrane
The Bacterial Nucleoid
Single loop of double stranded DNA that is attached to the cell envelope--no membrane separtes DNA from cytoplasm
~4e6 bp in many bacteria.
Supercoiling
The bacterial nucleoid is compacted via
Binary Fission
The growth of most microorganisms occurs by
Septum
A cell elongates slightly as it grows and the cytoplasm pinches in the middle at this location
Crosswall
Where the cell actually divides and adds a new wall at the cell equator
Bidirectionally
This is how DNA replicates, allowing it to begin the next replication before the cell divides
Septation
Occurs at the equator of the cell so that there is an equal division and each daughter cell has the same shape
Divisome
Division apparatus in the cell formed by Fts proteins
Fts Proteins
Required for cell division and chromosome replication
FtsZ Protein
Defines the division protein plane in prokaryotes; polymerizes to form a ring where the cell division will occur
FtsA Protein
ATP-hydrolyzing enzyme; provides energy for assembly of other proteins to the ring
Ftsl Protein
Involved in peptidoglycan synthesis for the new cell wall. Activity is blocked by penicillin
MreB
Helps define cell shape by directionally exerting pressure against CM
Filamentous Sprial Shaped Bands
MreB forms these bands around the inside of the cell under the cytoplasmic membrane
MreB
Coccus shaped bacteria lack this gene and therefore take on the default spherical bacteria shape
Glycan Units
These are inserted into preexisting wall material to synthesize a new cell wall during bacterial growth
Autolysins
Creates openings in existing cell wall to make space for new cell wall glycans to be inserted
Autolysis (Spontaneous Cell Lysis)
May occur if there is an error in inserting new cell wall material
Bactoprenol
Hydrophobic lipid alcohol that binds N-acetylglucosamine, N-acetylmuramic acid, and pentapide peptidoglycan precursors. Helps transport these new glycan unites through CM to become part of the growing cell wall
Transpeptidation
Formation of peptide crosslinks between NAMs and bonds peptidoglycan precursors into expanding peptidoglycan layer. Reaction is inhibited by penicillin and cell lysis occurs
Inclusion Granules
Densley compacted in the cytoplasm
Cell Inclusions
Prokaryotic cells often contain these granules that function as storage material or to orient the cell
Magnetosomes
Intracellular particles of magnetite that allow the organism to respond to a magnetic field
Anaerobic areas like mud or at the bottom of lakes
Where can magnetosomes be found?
1. Glycogen
2. Magnetosomes
3. Polyphsophate
4. Poly-B-hydroxybutyrate
5. Sulfur
What are examples of inclusion granules?
Polyphosphate
Inclusion granule that stores inorganic phosphate in prokaryotic cells
Glycogen and Poly-B-hydroxybutyrate
Inclusion granules that are used as a carbon and energy source
Sulfur
Inclusion granule that is used as an energy source in prokaryotic cells; some gram-negative prokaryotes can store this in its elemental form in globules in the periplasm
Fimbriae
Non-motile extensions that help bacteria attach to surfaces and to other bacteria; NOT for motility, strictly for attachment
Pili
Hollow, non-motile tubes made of protein called pilin that connect some cells. They are longer than fimbriae and shorter than flagella
Conjugation
PIli are used to move DNA from one cell to another by this process
Capsule/Slime Layer/Gycocalyx
Sticky polsaccharide layer surrounding the cell and helps the cell attach to objects
Phagocytosis and Dessication
The capsule protects the cell from:
Flagella
Long, helical protein filaments that is attached at the ends or over the whole cell
Proton Passage
Drives the CW or CCW rotation of the flagella to propel the cell
Rotate
Movement of bacterial flagella
Whip-Like Motion
Movement of eukaryotic flagella
Monotrichous
Single flagellum at one end; when it looks more like a tail
Lophotrichous
Several flagella at one or both sides
Peritrouchous
Several flagella all around the cell
Amphitirichous
One flagella on each end
Basal Body, Hook, and Filament
3 parts that make up the structure of the flagella
Basal Body
Imbedded within the cell envelope
Central Rod
The basal body is made of 2 or 4 protein rings connected by a
C ring
G+ and G-
MS ring
G+ and G-
P ring
G- only
L ring
G-only
C ring
Ring that is located in the cytoplasm and attaches to the inner surface of the cytoplasmic membrane
MS ring
Ring that is located in the cytoplasmic membrane
P ring
Ring that is located in the peptidoglycan layer
L ring
Ring that is located in the LPS layer
Hook
Curved structure made of protein; connects filament to basal body
Filament
Long, rigid, helical structures made of a protein call flagellin
Slime Secretion
Gliding can occur through this way that moves the cell along a solid surface
Chemotaxis
Directed movement of organisms in response to chemical signals
Phototaxis
Directed movement of organisms in response to light
Aerotaxis
Directed movement of organisms in response to oxygen
Osmotaxis
Directed movement of organisms in response to ionic strength
CCW rotation
Attractants cause what kind of rotation?
Flagella bundle together and push the cell forward ("run")
What occurs in CCW rotation?
CW rotation
Repellents cause what kind of rotation?
Flagella fly apart and "Tumble"--change direction
What occurs in CW rotation?
"Random Walk"
What do runs + tumbles cause?
Receptors
What detects attractant concentrations like sugars and amino acids?
Attractant Concentration
What increases and prolongs the run so that the net movement of bacteria is toward the attractants?
Phospholipids and Proteins
What is the cytoplasmic membrane made out of?
Hydrophilic
The outside layer of the cytoplasmic membrane is?
Hydrophobic
The inside layer of the cytoplasmic membrane is?
Transport, bioenergetics, and chemotaxis
The structural support function of the cytoplasmic membrane is the sit of many proteins involved in?
Peptidoglycan (Bacterial Cell Wall)
What consists of sugar chains wrapped in circles around the cell that are linked to each other by short chains of amino acids?
"Sweet"
"Glyco"=?
"Peptide"
Amino Acid=?
Chains
The backbone sugars of peptidoglycan are arranged in?
Between N-acytelmuramic acids
Where are the crosslinks located for peptidoglycan?
Peptidoglycan
What is a great target for antibiotics?
Resistant Straints
Widespread use of antibiotics selects for?
Pseudopeptidoglycan
Lysozome doesn't have an effect this, which is what some Archaea cell walls are made of
Plasmids
Where are resistant genes usually located on prokaryotes?
Under the Cytoplasmic Membrane
Where does MreB form the filamentous spiral shaped bands inside of the cell?
Bactoprenol
What helps transfer the new glycan unites through the CM to become part of the growing cell wall?
Hydrophobic Lipid Alcohol
What is Bactoprenol?
Transpeptidation
What bonds peptidoglycan precursors into the expanding peptidoglycan layer?
Spirochetes
What organism is the amphitrichous arrangement typically seen in?
2
How many protein rings make up a Gram-positive bacteria?
4
How many protein rings make up a Gram-negative bacteria?
C ring and MS ring
What protein rings are seen in Gram-positive and Gram-negative bacteria?
P ring and L ring
What protein rings are only seen in Gram-negative bacteria?
MS ring
What ring is the end of the central rod attached to?
The inner surface of the cytoplasmic membrane
What is the C ring attached to?
Filamentous cyanobacteria, Myxococcus, Cytophage, and Flavobacterium
What prokaryotes move by gliding motility instead of flagella?
Taxes
What are the directed movements toward or away from a chemical or physical gradient in the environment known as?