topic 2

• cellular membrane rolls are to isolate cells from the environment and organize intracellular pathways into subcellular compartments
• Types of lipids: phospholipids, glycolipids, cholesterol, sphingolipids
• cholesterol increases fluidity while decreasing permeability (prevents leaking)
• membrane heterogeneity means it's not symmetrical
• Lipid protein ratio varies greatly depending on: membrane type, organism and cell type
• Two types of membrane proteins: integral membrane proteins and peripheral membrane proteins
• Integral membranes are tightly bound to the membrane and are embedded in bilayer or spanning the entire membrane (penetrates lipid bilayer)
• Peripheral membranes are weakly associated with the lipid bilayer
• semipermeable membrane: allows some molecules to cross while restricting others
• osmosis: diffusion of water
• osmotic pressure: force associated with the diffusion of water
• osmolarity: ability of solution to induce water to diffuse across a membrane (concentration is impt)
• hyperosmotic, very ionic, hypertonic, high ion concentration
• hyperosmotic- higher osmolarity
• hyposmotic- lower osmolarity
• isosmotic- osmolarities are the same
• water diffuses from a HYPOSMOTIC solution to HYPEROSMOTIC solution (low to high)
• Tonicity- the affect of a solution on cell volume
• hypertonic- cells shrink, water leaves the cell
• hypotonic- cell swells, water enters the cell
• isotonic- net movement of water in the cell
• types of transport: passive, facilitated diffusion and active transport
• passive diffusion and facilitated diffusion do not require energy consumption
• facilitated diffusion and passive diffusion goes from high to low concentration
• active transport must consume energy and goes from low to high concentration
• passive diffusion is linear, same rate that goes in comes out
• facilitated diffusion requires a transporter protein, ion channel needed, and it levels out. saturation will be reached because proteins are limited and limit can be different over time
• glucose goes from high concentration to low concentration
• examples of ion channels are voltage-gated, ligand-gated, and mechanogated
• voltage-gated ion channels get opened or triggered by voltage change
• ligated-gated ion channels are determined by ligands not the membrane body difference
• mechanogated ion channels occurs if there is a pressure it will open
• types of active transport: primary active transport and secondary active transport
• primary active transport will always consume ATP, a direct energy source.
• secondary active transport occurs when there is NO ATP, couples the movement of one molecule to the movement of a target molecule
• primary active transporters are ATPases (enzymes that consumes ATP)
• an example of primary active transport would be the sodium-potassium pump. it actively transports sodium out and potassium in (2 potassium in and 3 sodium out)
• ABC (ATP Binding Cassette) transporters can transport drugs out of the cell
• secondary active transport has an antiport (exchanger) which the molecules move in opposite directions. symport (cotransporter) which molecules move in the same direction
• in small intestine high glucose concentration is bad