Long Exam 1 Flashcards
Consists of series of layered structures that surround the cytoplasm and govern cellular interactions with the external environment.
Cell envelope
Functions of cell envelope
1.) governs transport of nutrients into the cell and wastes out of the cell
2.) the site of energy conservation
3.) governs cell shape and structural integrity
4.) protects the cell from mechanical stress
5.) helps the cell attach to surfaces and even protect the cell from attack
Short definition of cytoplasmic membrane
It surrounds the cytoplasm
The mixture of macromolecules and small molecules inside the cell and separates it from the environment
cytoplasm
Main purpose of the cytoplasmic membrane
selective permeability
Common ground of the cytoplasmic membrane of all the bacterial and eukaryal cells
phospholipid bilayer containing embedded proteins
Major components of phospholipid bilayer
hydrophilic polar head (phosphate)
hydrophobic nonpolar tail (fatty acid)
The linkage that binds the hydrophobic fatty acid tails to glycerol in eukarya and bacteria
ester linkage
The linkage that binds the hydrophobic fatty acid tails to glycerol in Archaea
ether linkage
The hydrophobic portion in the lipids of Archaea
isoprenoid
What forms the hydrophobic region of archaeal membranes
repeating units of the five-carbon isoprene
Phosphoglycerol (phythanyl) or diphosphoglycerol (biphythanyl) makes up what structure of Archaea?
cytoplasmic membrane
The cytoplasmic membrane of Archaea is made up of?
Phosphoglycerol (phythanyl) or diphosphoglycerol (biphythanyl) makes up what structure of Archaea?
Number of carbons in:
Phythanyl side chain?
Biphythanyl side chain?
Phythanyl - C20
Biphythanyl - C40
The parent structure of phythanyl
Isoprene
Function of cytoplasmic membrane
1.) permeability barrier (prevents leakage and functions as a gateway for transport of nutrients into and wastes out of the cell)
2.) protein anchor: site of proteins that participate in transport, bioenergetics, and chemotaxis
3.) energy conservation: site of generation and dissipation of the proton motive force
The cytoplasmic membrane is a barrier to the diffusion of most substances, especially what type of molecules?
polar and charged molecules
Gram-positive and gram-negative classification in bacteria is based on the organization what structure?
Cell envelope
Describe the cell envelope of gram-positive bacteria.
contains:
-cytoplasmic membrane
-thick cell wall
Describe the cell envelope of gram-negative bacteria.
contains:
-cell wall
-outer membrane
-periplasm
Describe periplasm.
A compartment between the cytoplasmic membrane and outer membrane.
Gram stain reaction is determined by what?
Thickness of the cell wall (not the number of layers or the structure of the cell envelope)
The major component of bacterial cell wall which is a rigid polysaccharide that confers structural strength on the cell.
peptidoglycan
The sugar backbone of peptidoglycan is composed of alternating repeats of what modified glucose residues? What linkage? Attached to the latter residue is what?
N-acetylglucosamine, N-acetylmuramic acid joined by B-1,4 linkage
short peptide chain
In E.coli, the peptide chain of the peptidoglycan contains what amino acid residues?
L-alanine
D-alanine
D-glutamic acid
Diaminopelic acid (DAP)
Unusual feature of peptidoglycan
D-amino acids (since amino acids are usually in the L-isomer)
The constituents of peptidoglycan are connected in an ordered way to form what?
tetrapeptide
They are also called as “transmembrane proteins”. These types of proteins are significantly embedded in the membrane
Integral membrane proteins
This type of proteins typically interact with integral membrane proteins in cellular metabolism such as energy metabolism and transport
Peripheral membrane protein
Differentiate Bacteria, Eukarya, Archaea in terms of:
Hydrophobic portion of the membrane
Linkage
Presence of Peptidoglycan
Cell wall content
Archaea: Isoprenoid, ether, no peptidoglycan, S-layer
Bacteria: Fatty acid, ester, have peptidoglycan, some with S-layer
Eukarya: Fatty acid, ester, no peptidoglycan, no cell wall
A process by which the cells accumulate solutes against the concentration gradient
Active Transport
What are the three basic mechanisms of active transport in prokaryotic cells
Simple transport system
Group translocation
ABC transport system
An active transport mechanism in prokaryotic cells that consists only of a transmembrane protein. It is driven by the energy inherent in the proton motive force.
Simple transport system
Two types of simple transport system. Differentiate.
Symport - a solute and a proton are cotransported in the same direction
Antiport - a solute and a proton are cotransported in the opposite direction
A type of active transport mechanism that employs a series of proteins in the transport event.
Group translocation
Group translocation active transport differs in what two ways?
- The transported substance is chemically modified during the transport process
- An energy-rick compound drives the transport event
An active transport system that consists of a binding protein, transmembrane transporter, and ATP-hydrolyzing protein
ABC (ATP-binding cassette) transport systems
Electron transport of cellular respiration in bacterium occurs in?
Plasma membrane
A component of bacterial cell wall (particularly in Gram-positive bacteria) that is composed of glycerol phosphate and ribitol phosphate with attached molecules of glucose or D-alanine or both.
Teichoic acids
In E.coli, the crosslinking of peptidoglycan layers occurs between what amino acids?
D-alanine and meso-DAP
A component of bacterial cell wall (particularly in Gram-positive bacteria) that is composed of glycerol phosphate and ribitol phosphate attached with lipids instead of peptidoglycan.
Lipoteichoic acid
Archaeans lack these structures
peptidoglycan, outer membrane
Cell walls of Archaeans are made up of what polysaccharides? What linkage?
Pseudomurein. N-acetylglucosamine and N-acetyltalosaminuronic acid linked by B-1,3-linkage
Functions of lipopolysaccharide
- facilitate cell surface recognition
- virulence factors for some bacterial pathogens
- contribute mechanical strength to the cells
What are the components of LPS?
Core polysaccharide, O specific polysaccharide, Lipid A
The core polysaccharide of LPS consists of?
Ketodeoxyoctonate (KDO)
Heptoses
Hexose sugars such as glucose and galactose, N-acetylglucosamine
O-specific polysaccharides consist of?
Galactose, Glucose, Rhamnose, Mannose, one or more dideohexoses (such as abquose, colitose, paratose, tyvelose)
A component of Gram-negative bacteria that anchors the membrane to the peptidoglycan layer. It is a molecule that spans the gap between the LPS layer and the peptidoglycan layer.
Braun lipoprotein
The toxic component of LPS. It causes violent symptoms in humans, including gas, diarrhea, and vomiting.
Lipid A (secretion of endotoxin)
Located on the outer membrane of the gram-negative bacteria. It functions as channels for the entrance and exits of solutes.
Porins
What is an S-layer?
Found in Bacteria and in nearly all in Archaea. It consists of paracrystalline monolayer of interlocking molecules of proteins or glycoprotein.
Repeating units of rigid yet permeable paracrystalline structure
These are terms used to descibe cell surface layers.
capsule and slime layers (glycocalyx)
Describe and give the functions of capsules and slime layers.
-polysaccharide layers
-assist in attachment to surfaces
-contributes to biofilm formation
-serves as virulence factors in certain bacteria
-resist dessication
-complement-mediated killing
This is a structure organized in a tight matrix that is more visible under the microscope using India ink (which contains particulates that stain the background but cannot penetrate the capsule).
Capsule
Loosely attached polysaccharide coat. It can be easily deformed and can be lost from the cell surface.
Slime layer
Thin, filamentous structures made of protein that extend from the surface of a cell and can have many functions. These are longer than fimbriae.
Pili
What is the main function of pili?
Enable bacterial cells to stick to surfaces
A type of pili that facilitate genetic exchange by causing cell-to-cell attchment.
Conjugative Pili
A type of pili that is also known as “nanowires”. They can conduct electrons toward or away from the cell and in doing so play an important role in the energy metabolism of diverse microbes.
Electrically-conductive Pili
A type of pili that facilitates adhesion but also support an unusual form of cell movement called “twitching motility in certain bacterial species.
Type IV pili
A structure that resembles a tiny grappling hook. It functions to affix cells to a surface to form networked biofilm. It structurally resembles type IV pili except for their barbed terminus, which functions to attach cells both to surfaces to each other.
Hami
What are the two carbon-storage polymers?
Poly-B-hydroxybutyric acid (PHB) and glycogen
Formed when phosphate is in excess and can be drawn upon as a source of phosphate for nucleic acid and phospholipid biosynthesis when phosphate is limiting. It can be broken down to synthesize the energy-rich compound ATP from ADP.
Polyphosphate
Cell inclusion that confer buoyancy in planktonic cells and allow the cells to position themselves in regions of the water column that best suit their metabolisms.
Gas vesicles
A protein of gas vesicles that forms watertight vesicle shell that forms the parallel “ribs” of the vesicle and resists pressure from the outside.
GvpA
The protein in gas vesicle that strengthens the shell of the gas vesicle.
GvpC
These are spore structures that allow many microbes to survive unfavorable conditions.
Endospores
These two are the only groups of bacteria (particularly, gram-positive) that can produce endospores.
Bacillales and Clostridiales
The process of cellular differentitation that results in endospore formation.
Sporulation
What triggers sporulation?
When some nutrients become limiting.
A structure that assists in bacterial locomotion (swimming)
Flagella
What are the three arrangements of flagellum?
- Petrichous
- Polar
- Lophotrichous
[Flagellum structure] The main part of flagellum; composed of many copies of a protein called “flagellin”
Filament
[Flagellum structure] A wider region at the base of the filament. It consists of a single type of protein and connects the filament to the flagellum motor in the basal body.
Hook
[Flagellum structure] A reversible rotating machine composed of more than 25 proteins and anchored in the cytoplasmic membrane cell wall.
Flagellum motor
Flagellum motor consists of?
-L-ring
-P-ring
-MS and C rings
