M3a L25 Flashcards
Outline the functions of cell membranes
barrier, selective permeability to polar, hydrophobic, small and large molecules/ions
maintains the electrochemical gradient for energy metabolism and transduction
maintains homeostasis
provides hydrophobic environment
signal transduction
Describe the effect of aspirin and ibuprofen on PGH synthase
aspirin causes covalent modification of ser530, which blocks arachidonic acid access, inhibiting prostaglandin production
ibuprofen is a reversible competitive inhibitor, its binding blocks arachidonic acid or aspirin from reaching the PGHS active site, thus inhibiting the enzyme
Describe prostaglandin synthase and outline the physiological roles of its products
an integral membrane enzyme
target for NSAIDs
cells synthesize eicosanoid hormones, prostaglandins from arachidonic acid, they are local hormones affecting nearby cells
it faces lumen of endoplasmic reticulum, its dimeric, its anchored in the membrane by hydrophobic helices
Outline the organization and roles of proteins within the membrane
energy transduction,
membrane transport; shuttle and transport systems,
metabolism, some enzyme reactions occur better in a membrane than in aqueous solution
signal transduction; glucagon and insulin hormone signaling, occurs systems that are proteins that are embedded in the membrane
Briefly describe the fluid mosaic model
The fluid mosaic model explains various characteristics regarding the structure of functional cell membranes. According to this biological model, there is a lipid bilayer in which protein molecules are embedded. The phospholipid bilayer gives fluidity and elasticity to the membrane. Small amounts of carbohydrates are also found in the cell membrane.
Outline the roles of glycolipids and glycoproteins in cell
membranes
glycolipids are carbs attached to lipids
glycoproteins are carbs attached to proteins
cell-cell recognition, cell adhesion, transporting signals
Outline the role of cholesterol in cell membranes
helps regulate fluidity of membranes, it inserts into the membrane, Hydrophilic OH group can interact with the polar head groups of the phospholipids and aqueous solution of the outside of the cell. Hydrophobic part of cholesterol will interact via hydrophobic effect and form hydrophobic associations with the hydrophobic fatty acyl tails of the phospholipid regulate how well the phospholipids pack with one another, acting as a spacer, fluidity butter, can stop membranes from being too fluid or too rigid
Describe the phospholipid bilayer of animal membranes
Phospholipids comprise a phosphate containing head group, a glycerol backbone and two fatty acyl tails. Both can be diverse. Phospholipids have a phospho head or a polar head, can be hydrophilic and charged or uncharged
