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