CH3 Flashcards
Prokaryotic Cell Structure
Cytoplasmic membrane
Cell wall
Cell wall + Cytoplasmic membrane = _______
Capsule or slime layer (_________)
Filamentous protein appendages (_______and ______)
(chromosomes, ribosomes, plasmids, storage granules, endospores) are the _____________
Cytoplasmic membrane
Cell wall
Cell wall + Cytoplasmic membrane = cell envelope
- Capsule or slime layer* (glycocalyx)
- Filamentous protein appendages* (flagella and pili)
Internal structures (chromosomes, ribosomes, plasmids, storage granules, endospores)
Cytoplasmic Membrane
A.K.A _____membrane A.K.A ______membrane
_________cytoplasmic membranes have same general structure as membranes of all other cells
Fluid-mosaic model
Phospholipids in membrane are in ____state and proteins are _______ among the lipids in the membrane forming a ________
Membrane phospholipids form a _______
Charged phosphate end of molecule are ________ and interact with watery environment
Fatty-acid end consists of nonpolar hydrocarbons chains which are _________
A.K.A cell** membrane A.K.A **plasma membrane
Prokaryotic cytoplasmic membranes have same general structure as membranes of all other cells
Fluid-mosaic model
Phospholipids in membrane are in fluid state and proteins are dispersed among the lipids in the membrane forming a mosaic
Membrane phospholipids form a bilayer
Charged phosphate end of molecule are hydrophilic and interact with watery environment
Fatty-acid end consists of nonpolar hydrocarbons chains which are hydrophobic
Cytoplasmic Membrane
- Interspersed among lipid molecules are protein molecules*
- ________ are not stationary, constantly changing position
- Proteins function as ________ and _________ gates
- Provides mechanism to sense _____________
Serves three roles
Defines the ________ of the cell
As a ___________barrier
As a site of _______
Cytoplasmic Membrane
- Interspersed among lipid molecules are protein molecules*
- Proteins are not stationary, constantly changing position
- Proteins function as receptors and transport gates
- Provides mechanism to sense surroundings
Serves three roles
Defines the boundary of the cell
As a semipermeable barrier
As a site of energy
The Cytoplasmic Membrane as a Semipermeable Barrier
Cytoplasmic membrane is selectively permeable but …
Some molecules pass freely through the cytoplasmic membrane by ___________
Water, certain gases and small hydrophobic molecules pass through via __________
The Cytoplasmic Membrane as a Semipermeable Barrier
Cytoplasmic membrane is selectively permeable but …
Some molecules pass freely through the cytoplasmic membrane by simple diffusion
Water, certain gases and small hydrophobic molecules pass through via simple diffusion
The Cytoplasmic Membrane as a Semipermeable Barrier
___________The ability of water to flow freely across the cytoplasmic membrane
- Water flows to _____ solute concentrations inside and outside the cell
- The environment in which ________ normally grow contains a ______amount of solute while ____ contains ________ amount of solute
- _____ of water exerts osmotic pressure on membrane
Membrane rupture is prevented by rigid cell wall of bacteria
Damage to cell wall can allow cells to burst or_____
Osmosis
The ability of water to flow freely across the cytoplasmic membrane
Water flows to equalize solute concentrations inside and outside the cell
The environment in which prokaryotes normally grow contains a small amount of solute while cytoplasm contains large amount of solute
Inflow of water exerts osmotic pressure on membrane
Membrane rupture is prevented by rigid cell wall of bacteria
Damage to cell wall can allow cells to burst or lyse
The Cytoplasmic Membrane as a Semipermeable Barrier
__________ _________ moves impermeable compounds across membrane exploiting a concentration gradient
Using ________ _______ (A.K.A permeases or carriers)
Flow from area of greater concentration to area of lesser concentration
*Molecules are transported until__________ is reached
System can only ______concentration gradient it cannot create one
No _____is required for facilitated diffusion
Rare in _______, but glycerol enters E. coli this way
The Cytoplasmic Membrane as a Semipermeable Barrier
Facilitated diffusion moves impermeable compounds across membrane exploiting a concentration gradient
Using transport proteins (A.K.A permeases or carriers)
Flow from area of greater concentration to area of lesser concentration
Molecules are transported until equilibrium is reached
System can only eliminate concentration gradient it cannot create one
No energy is required for facilitated diffusion
Rare in prokaryotes, but glycerol enters E. coli this way
The Cytoplasmic Membrane as a Semipermeable Barrier
________ ________moves impermeable compounds ______ a concentration gradient
Requires an expenditure of ______
Three primary mechanisms in prokaryotes
_______ motive force
______ Binding Cassette system
Group ______
The Cytoplasmic Membrane as a Semipermeable Barrier
Active transport moves impermeable compounds against a concentration gradient
Requires an expenditure of energy
Three primary mechanisms in prokaryotes
_Proton motive force
ATP Binding Cassette system
Group translocation_
Term- Transporters allow protons into cell: _________
______ either bring in or expel other substances
E.g., The ________ that transports lactose into bacteria
E.g., ________pumps used in antimicrobial resistance
Proton motive force
Transporters allow protons into cell
Protons either bring in or expel other substances
E.g., The permease that transports lactose into bacteria
E.g., Efflux pumps used in antimicrobial resistance
________________(ABC transport)
(Sometimes) use binding proteins to scavenge and deliver molecules to transport complex
E.g., ________transport
ATP Binding Cassette system *(ABC transport)*
(Sometimes) use binding proteins to scavenge and deliver molecules to transport complex
E.g., Maltose transport
Transport mechanism that chemically alters molecule during passage:________
Therefore uptake of molecule does not ______ concentration gradient
E.g., _____________ system
-Phosphorylates sugar molecule during transport
Phosphorylation changes molecule and therefore does not change sugar balance across the membrane
Group translocation
Transport mechanism that chemically alters molecule during passage
*Therefore uptake of molecule does not alter concentration gradient
E.g., Phosphotransferase system
*Phosphorylates sugar molecule during transport
Phosphorylation changes molecule and therefore does not change sugar balance across the membrane*
Cytoplasmic Membrane as the Site of Energy Production
Membrane also the site of energy production
Energy produced through series of embedded _____
- ________ transport chain
- ________are used in the formation of proton motive force
- Energy produced in proton motive force is used to drive other transport mechanisms or to create _______
Cytoplasmic Membrane as the Site of Energy Production
Membrane also the site of energy production
Energy produced through series of embedded proteins
-Electron transport chain
-Proteins are used in the formation of proton motive force
-Energy produced in proton motive force is used to drive other transport mechanisms or to create ATP
Cell Wall
_______structure that surrounds cytoplasmic membrane
Determines ______ of bacteria and prevents cell from ___
Rigidity of cell wall is due to __________ (PTG)
Compound found only in ________
Basic structure of peptidoglycan
-Alternating series of two subunits
_____________ (NAG)
_____________(NAM)
-Joined subunits form _______ chain
& held together by string of four amino acids called _________ chain
Gram-positive and Gram-negative bacteria have ________different cell walls
Cell Wall
Rigid structure that surrounds cytoplasmic membrane
Determines shape of bacteria and prevents cell from bursting
Rigidity of cell wall is due to peptidoglycan (PTG)
Compound found only in bacteria
Basic structure of peptidoglycan
-Alternating series of two subunits
_N-acetylglucosamin (NAG)
N-acetylmuramic acid (NAM)_
-Joined subunits form glycan chain
Glycan chains held together by string of four amino acids called Tetrapeptide chain
Gram-positive and Gram-negative bacteria have slightly different cell walls
Gram Positive Cell Wall
Relatively thick layer of _________
-As many as 30 layers
Regardless of thickness, _______ is _______ to numerous substances
_________acid component of PTG
Gives cell _________ charge
Gram Positive Cell Wall
Relatively thick layer of PTG
As many as 30 layers
Regardless of thickness, PTG is permeable to numerous substances
Teichoic acid component of PTG
Gives cell negative charge
Gram Negative Cell Wall
Thin layer of _________
________ sandwiched between ______membrane and ___________ membrane
Outer membrane is Constructed of lipid_______
Much like cytoplasmic membrane but outer leaflet made of __________ not phospholipids
A.K.A___________ layer or LPS layer
Portions of LPS are medically significant (LPS called ________ because elicits immune response so strong that the even our own cells are damaged)
_*O-specific_ polysaccharide side chain
E.g., E. coli O157:H7
_*Lipid A_ - the portion of LPS anchored in the lipid _____
Gram Negative Cell Wall
Thin layer of PTG
PTG sandwiched between outer** membrane and **cytoplasmic membrane
Outer membrane is Constructed of lipid bilayer
Much like cytoplasmic membrane but outer leaflet made of lipopolysaccharides not phospholipids
A.K.A lipopolysaccharide layer or LPS layer
Portions of LPS are medically significant (LPS called endotoxin because elicits immune response so strong that the even our own cells are damaged)
*O-specific polysaccharide side chain
E.g., E. coli O157:H7
*Lipid A - the portion of LPS anchored in the lipid bilayer
Gram Negative Cell Wall
LPS severs as barrier to a large number of molecules so channels called________ required
Region between outer membrane and cytoplasmic membrane is called ________
Most secreted proteins contained here unless transported across outer membrane as well
Binding proteins of _______ transport system located here
Gram Negative Cell Wall
LPS severs as barrier to a large number of molecules so channels called porins required
Region between outer membrane and cytoplasmic membrane is called periplasm
Most secreted proteins contained here unless transported across outer membrane as well
Binding proteins of ABC transport system located here
Layers External to Cell Wall
- *Capsules and Slime Layer*
- _________ is a distinct gelatinous layer
- _________layer is irregular diffuse layer
*General function
_________from host defenses
Enables bacteria to ________ to specific surfaces
*Chemical composition varies depending on bacterial species
*Most are made of __________
Referred to as glycocalyx
Glyco = ______ calyx = ______
___________ _________ produces a slime layer used to make xanthan gum, used as a _____and______agent in salad dressings, ice creams, toothpastes, etc.
Layers External to Cell Wall
- *Capsules and Slime Layer*
- Capsule is a distinct gelatinous layer
- Slime layer is irregular diffuse layer
*General function
Protection from host defenses
Enables bacteria to adhere to specific surfaces
*Chemical composition varies depending on bacterial species
Most are made of polysaccharide
Referred to as glycocalyx
Glyco = sugar calyx = shell
Xanthomonas campestris produces a slime layer used to make xanthan gum, used as a gelling and stabilizing agent in salad dressings, ice creams, toothpastes, etc.
Some bacteria have protein_________
- Aid in survival in certain environments
- **___________***
- Long protein structure
- Responsible for motility
- Use ________ like movements to push bacteria
- Chemotaxis
*Some important in bacterial pathogenesis
-H. pylori penetration through mucous coat
- *Location* can aid in __________
- E.g., E. coli have flagella over entire surface (peritrichous) while others have a polar flagellum (monotrichou*s
Some bacteria have protein appendages
- Aid in survival* in certain environments
- *Flagella**
- Long protein structure
- Responsible for motility
- Use propeller like movements to push bacteria
- Chemotaxis
*Some important in bacterial pathogenesis
H. pylori penetration through mucous coat
- _*Location_* can aid in identification
- E.g., E. coli have flagella over entire surface (peritrichous) while others have a polar flagellum (monotrichous*
(_______)
- Considerably shorter and thinner than flagella
- Similar in structure
- Protein subunits
Function
________- these pili called fimbriae
________– twitching motility
________ - Mechanism of DNA transfer, e.g. F-pilus
(Pili)
- Considerably shorter and thinner than flagella
- Similar in structure
- Protein subunits
- *Function**
- *Attachment** - these pili called fimbriae
- *Movement** – twitching motility
- *Conjugation** - Mechanism of DNA transfer, e.g. F-pilus
- **______________***
- Resides in cytoplasm
- In nucleoid space
- Typically single ________
- Circular double-stranded molecule
- Contains all genetic information
Chromosome
- Resides in cytoplasm
- In nucleoid space
- Typically single chromosome
- Circular double-stranded molecule
- -Contains all genetic information*
*____________*
- Circular DNA molecule
- Generally 0.1% to 10% size of chromosome
*_______chromosomal
-Independently replicating
*Encode characteristic
- Potentially enhances _________
- Antimicrobial __________
Plasmid
Circular DNA molecule
Generally 0.1% to 10% size of chromosome
_*Extra_chromosomal
Independently replicating
*Encode characteristic
Potentially enhances survival
Antimicrobial resistance
-Involved in protein synthesis
-Composed of large and small subunits
+Units made of riboprotein and ribosomal RNA
-__________ ribosomal subunits
Large = 50S
Small = 30S
Total = 70S
-Different than _________ ribosomes
40S, 60S, 80S
-Difference often used as target for __________
Ribosome
-Involved in protein synthesis
-Composed of large and small subunits
+Units made of riboprotein and ribosomal RNA
-Prokaryotic ribosomal subunits
Large = 50S
Small = 30S
Total = 70S
-Different than eukaryotic ribosomes
40S, 60S, 80S
-Difference often used as target for antimicrobials
(___________)
-Dormant cell types
-Produced through sporulation
Theoretically remain dormant for 100 years
-Resistant to damaging conditions
Heat, desiccation, chemicals and UV light
__________ _____produced through germination
Germination occurs after exposure to heat or chemicals
Germination not a source
Common bacteria genus that produce endospores include ________ and ___________
Endospores
Dormant cell types
Produced through sporulation
Theoretically remain dormant for 100 years
- Resistant* to damaging conditions
- Heat, desiccation, chemicals and UV light
- *Vegetative cell** produced through germination
- Germination occurs after exposure to heat or chemicals
- Germination not a source
Common bacteria genus that produce endospores include Clostridium and Bacillus
