lecture 11: microbial membranes Flashcards
(13 cards)
Who has ester linkages, and who uses ether?
Bacteria and Eukarya have ester linkages in their phospholipids.
Archaea have ether linkages in their phospholipids.
Who uses isoprene?
Archaea uses isoprenes instead of fatty acids in their membrane lipids.
Why types of cell membranes exist in Archaea? What are they made of?
Lipid monolayers, bilayers, or a mixture exist in Archaea, and they are made of glycerol diethers and tetraethers with isoprenes (phytanyl or biphenyl) instead of fatty acids.
What are some functions of a cell membrane?
Permeability barrier: controls entry and exit of substances.
Protein anchor: holds transport proteins in place.
Energy conservation: site for the proton motive force (PMF)
Is Passive Diffusion simple or facilitated? Is energy needed?
Simple diffusion: movement of substances across the membrane without a transporter (no energy needed)
Facilitated diffusion: requires a transport protein but does not require energy.
In osmosis, where does the water flow in isotonic/hypertonic/hypotonic situations?
Isotonic: no net water movement
Hypertonic: water moves OUT of the cell (cell shrinks)
Hypotonic: water moves INTO the cell (cell swells)
Why might bacterial cells survive and not eukaryotic cells in certain situations during osmosis?
Bacterial cell walls provide structure support, preventing lysis in hypotonic environments, while eukaryotic cells (cells without cell walls) are more prone to bursting.
Do the bacterial cells actually pop/lyse in osmosis?
Not usually they do not because the cell wall prevents it, expect in cases where the cell wall is damaged (antibiotics like penicillin).
Does active transport go with or against the concentration gradient? Energy?
Moves against the concentration gradient (low to high)
Requires energy, usually from ATP or the Proton Motive Force (PMF).
Is active transport much faster than passive diffusion- why is this important?
Active trasnport is much father because, it allows bacteria to rapidly take in nutrients from low concentrations in the environment.
Active transport: proton motive force- what is this? why did we talk about it?
PMF is the energy generated by the movement of protons (H+) across the membrane.
PMF is used for ATP synthesis, active transport, and motility (flagella movement).
What are the three transport systems in prokaryotes? How does each work? How are they powered? What is an example of each? How do these work?
Simple transport: driven by PMF (ex. Lac permease for lactose uptake in E.coli)
Group Translocation: transported substance is chemically modified (ex. Phosphotransferase system- PTS- for glucose transport).
ABC transporters: uses ATP and periplasmic binding proteins (ex. Uptakes of suhars, amino acids, trace metals).
What is the difference between uni/syn/antiporters?
Uniporters: transport one molecule in one direction.
Symporters: transport two molecules together in the same direction.
Antiporters: transport one molecule in, one out.
