Lecture 4 Flashcards
Size range for prokaryotes
0.2um to >700um in diameter
Size range for eukaryotes
10 to >200um in diameter
advantages to being small
- more surface area realative to volume
- greater nutrient exchange per unit cell volume
- tend to grow faster
Functions of membranes
- permeability barrier
- anchor for proteins
- site for energy conservation (ETC)
The cytoplasmic membrane is __________ wide.
8-10nm
The cytoplasmic membrane is stabilized by..
hydrogen bonds and hydrophobic interactions
____ and ____ help stabilize the membrane by forming ionic bonds with negative charges on the phospholipids.
Mg2+, Ca2+
Outer surface of cytoplasmic membrane
can interact with a variety of proteins that bind substrates or process large molecules for transport
Inner surface of cytoplasmic membrane
interacts with proteins involved in energy‐yielding reactions and other important cellular functions
intergral membrane proteins
firmly embedded in the membrane
peripheral membrane proteins
one portion anchored in membrane
____ linkages in phospholipids of Archaea.
Ether
Bacteria and Eukarya have ____ linkages in phospholipids
ester
Archaeal lipids lack _________; have _______ instead.
fatty acids, isoprenes
Major lipids in archaea membranes are…
glycerol diethers and tetraethers
Archaeal membranes can exist as lipid…
monolayers (high temperature), bilayers, or mixtures
Polar and charged molecules must be…
transported
transport proteins
accumulate solutes against the conc. gradient
protein anchor
holds transport proteins in place; site of many proteins that participate in transport, bioenergetics, and chemotaxis
energy conservation
site of generation and dissipation of proton motive force
3 major classes of transport systems in prokaryotes
- simple transport
- group translocation
- ABC system
Which of the 3 major classes of transport systems in prokaryotes require energy?
ALL; usually proton motive force or ATP
simple transport
driven by the energy in the proton motive force
group translocation
chemical modification of the transported substance driven by phosphoenolpyruvate
ABC transporter
periplasmic binding proteins are involved and energy comes from ATP
Simple transport of lactose into E. coli
with transporter lac permease, an energy-driven (proton motive force), symporter
The phosphotransferase system in E. coli
- type of group translocation
- best studied system
- moves glucose, fructose, and mannose
- five proteins required
ABC (ATP-binding cassette) systems
- often involved in uptake organic compounds, inorganic nutrients, and trace metals
- high substrate specificity
Gram negatives of ABC systems
employ periplasmic‐binding proteins and ATP‐driven transport proteins
Gram positives of ABC systems
employ substrate‐binding proteins and membrane transport proteins
gram negative (pink) cell wall
peptidoglycan and outer membrane
gram positive (purple) cell wall
peptidoglycan
gram stain procedure
crystal violet, iodine, alcohol, safranin