Lecture 3- Membranes Flashcards
what are phospholipids
a lipid molecule that makes up the cell membrane
phospholipids move around freely ____
laterally
effect of high temperatures on membrane fluidity
-phospholipids have more kinetic energy
- increased tail length= increased hydrophobicity
-decreased C=C
-increased cholesterol content (also = increased hydrophobicity
-gap between phospholipids increases = more fluidity and less integrity
effect of low temps on membrane fluidity
-decreased hydrocarbon tail length=decreased hydrophobicity
-increased C=C
-increased cholesterol
-less gap between phospholipids
cholesterol modulates ______
membrane fluidity
integral membrane protein
interacts with hydrophobic core of membrane
peripheral membrane protein
associate with the cytoplasmic face of the membrane via integral membrane proteins
-protein-protein interactions often involve hydrophobic assoc.
list functions proteins have within the bilayer
transporters, enzymes, signal receptors, cell-cell recognition, attachment, attachment to extracellular matrix
permeable
a substance that can freely diffuse across a bilayer
impermeable
a substance that cannot cross the hydrophobic core because either too big or too polar
passive transport
permeable substances move down conc. gradient across bilayer
-high to low
hypotonic
high [solute] inside the cell, less outside
-water rushes in
isotonic
equal [solute] in cell and in blood
hypertonic
high [solute] outside, less inside
-water rushes out
facilitated diffusion
transport down conc. gradient with the help of a protein transporter (channel protein)
transport proteins are ____ and _______
specific;gated
what is active transport and why perform it?
transport of molecules up a conc. gradient using energy
-to concentrate nutrients in the cell
-expel waste
-to maintain/establish an electrochemical gradient
cotransport/coupled transport
transport of 2 molecules using the same transporter
-the source of energy for active transport
exocytosis
-secretion
-bulk transport of large molecules and/or quantities out of the cell
-non-specific uptake of extracellular solutes
receptor-mediated endocytosis (RME)
-phagocytosis of a specific ligand
ligand
substance that binds to a receptor
receptor
transmembrane protein that recognizes and binds a specific ligand
