BIOL 2085C EXAM 2 (COMPLETE & VERIFIED) FALL SEMESTER WITH ACCURATE
SOLUTIONS
Plasma Membrane Structure/Function
Structure: double layer of phospholipids with hydrophilic heads on outside and
hydrophobic tails on the inside
Lipids
Amphipathic molecules, 1 sat 1 unsat tail, various charged head portions
Proteins:
function as transporters/channels/anchors/receptors/enzymes
Carbs:
function as protection/lubrication/cell-cell recognition
Phospholipid Structure
2 fatty acid tails with 1 unsat and 1 sat
Fluidity of lipid bilayer
movement of phospholipids within the bilayer
Importance: protein diffusion/interactions, distribution of proteins/lipids, distribution into
daughter cells
,Scramblase
movement of phospholipids between the monolayers of the membrane
can move in both directions and happens randomly
Flippase
used during membrane asymmetry
movement of phospholipids from extracellular to cytosolic faces only
Asymmetry of lipid bilayer
flat vs circular bilayer
golgi and other membranes have a circular bilayer
ER membrane is flat so has random distribution of PLs
Generation steps
1. PLs are added to the cytosolic face of ER and scramblase will move them around
randomly
2. flippases in the golgi move them to cytosolic face to make circular structure
3. carbs added within the lumen to the non-cytosolic face
4. movement to non-cytosolic face to the outside of the cell to be extracellular facing
, Selective permeability in membrane
determines which molecules can enter the cell and those that cant
small non-polar molecules enter easily compared to others
Factors affecting membrane fluidity
Hydrocarbon length: shorter tails are more fluid than long ones (14-24 is normal)
Tail Saturation: more sat means less fluid because of more packing possible
Temperature: inc temp causes more fluidity as the chains become less rigid
bacteria: able to adjust the length of the hydrocarbon tails to maintain fluidity
cholesterol: helps keep fluidity in animal cells
Citric Acid Cycle
acetyl-coA act as an input
various steps yielding NADH, FADH2, and oxaloacetate to be used in ETC or the cycle again
SOLUTIONS
Plasma Membrane Structure/Function
Structure: double layer of phospholipids with hydrophilic heads on outside and
hydrophobic tails on the inside
Lipids
Amphipathic molecules, 1 sat 1 unsat tail, various charged head portions
Proteins:
function as transporters/channels/anchors/receptors/enzymes
Carbs:
function as protection/lubrication/cell-cell recognition
Phospholipid Structure
2 fatty acid tails with 1 unsat and 1 sat
Fluidity of lipid bilayer
movement of phospholipids within the bilayer
Importance: protein diffusion/interactions, distribution of proteins/lipids, distribution into
daughter cells
,Scramblase
movement of phospholipids between the monolayers of the membrane
can move in both directions and happens randomly
Flippase
used during membrane asymmetry
movement of phospholipids from extracellular to cytosolic faces only
Asymmetry of lipid bilayer
flat vs circular bilayer
golgi and other membranes have a circular bilayer
ER membrane is flat so has random distribution of PLs
Generation steps
1. PLs are added to the cytosolic face of ER and scramblase will move them around
randomly
2. flippases in the golgi move them to cytosolic face to make circular structure
3. carbs added within the lumen to the non-cytosolic face
4. movement to non-cytosolic face to the outside of the cell to be extracellular facing
, Selective permeability in membrane
determines which molecules can enter the cell and those that cant
small non-polar molecules enter easily compared to others
Factors affecting membrane fluidity
Hydrocarbon length: shorter tails are more fluid than long ones (14-24 is normal)
Tail Saturation: more sat means less fluid because of more packing possible
Temperature: inc temp causes more fluidity as the chains become less rigid
bacteria: able to adjust the length of the hydrocarbon tails to maintain fluidity
cholesterol: helps keep fluidity in animal cells
Citric Acid Cycle
acetyl-coA act as an input
various steps yielding NADH, FADH2, and oxaloacetate to be used in ETC or the cycle again
