Lecture 3

Created by gazar1990 

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pleiomorphic

a given microbe that has multiple morphologies

important macromolecules of cells

proteins, nucleic acids, polysaccharides, lipids

proteins

role: structural, catalytic
location: cytoplasm, cell surface, secreted)

nucleic acids

role: info, structural (RNA), catalytic (RNA)
location: genome, plasmids, ribosomes, cytoplasm

polysaccharides

role: structural, energy storage
location: peptidoglycan, outer membrane, storage granules

lipids

role: structural, energy storage
location: membrane, storage granules

bacterial cytoplasmic membrane

lipid bilayer-seperates in form out
structure- glycerol core, 2 carbons form ether links to hydrophobic f.a.
3rd carbon- links to hydrophilic phosphate head

cytoplasmic membrane proteins

Integral-mem channels, transporters, energy, metabolism, chemotaxis
Secreted- transported through membrane
Peripheral- mem anchor, similiar to integral, lipoprotein with anchor

Membrane Strengthening Agents

Sterols- eukaryotes
Hopanoids-bacteria, NOT archaea

Archaea Membranes

Ether betwen glycerol and hydrophobic side chain. not ESTER
isoprene as subunit for hydrophobic side chains rather than fatty acids

major lipids of archaea

glycerold diether (20 c)
diglycerol tetraether (40 c)

cytoplasmic membrane functions

permeability barrier
protein anchor
energy conservation

transmembrane proteins

increase rate of uptake across cytoplasmic membrane of solutes with low permeability

Transport Systems

Passive- no energy needed. aquaporins
Active- requires energy. simple transporters, group translocation, ABC transporter

simple transporters

Uniporters
Symporters
Antiporters
all have 12 alpha helices

ABC Transporters

ATP binding Cassette
3 parts- periplasmic binding protein, membrane spanning transporter, atp-hydrolyzing protein

translocases

secretion of proteins
can include: toxins, enzymes for degradation of large polymers (cellulose), and enzymes or recomponents for construction of cell structures outside cytoplasm

"cell walls" of bacteria

aka peptidoglycan layer
prevents osmotic lysis, gives cell shape, located outside cytoplasmic membrane

what is peptidoglycan sensitive to?

B-lactam antibiotics
lysozymes (tears saliva, etc)

B-lactam antibiotics

penicillin
bind to and inactivates transpeptidases
which are responsible for forming oligopeptide cross links in peptidoglycan
yields weakened cell wall and lysis

peptidoglycan

glycan= long polysaccharide made of 2 amino sugars linked B-1,4
peptido- made by oligopeptide cross links. made partly of d-amino acids

gram postive cell surface

thick peptido
2 phyla= firmicutes, actinobacteria
teichoic acid- acidic polymer of modified ribitol

gram negative cell surface

thin peptido
contains LPS layer
contains porins (3 channeled passive transporters)
space between membranes- periplasm

LPS

esp Lipid A can act as endotoxin

gram stain

gram negative= pink
gram postive= purple

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