BCMB 230 1st Edition Lecture 6 Outline of Last Lecture I.EnergyII.Cellular RespirationIII.Anaerobic RespirationIV.Protein and Amino Acid MetabolismV.Fat MetabolismOutline of Current Lecture I.DiffusionII.Different Types of DiffusionIII.Exocytosis and EndocytosisIV.OsmosisV.TonicityCurrent LectureMolecular Movement I. DiffusionDiffusion is the primary mechanism for moving things around the cells. Solutes move down the gradient/with the gradient. If there is a great difference between both sides of the gradient, it is called a steep gradient. Eventually, equilibrium will be reached—particles can be equally distributed, but this is not always the case.Things that concern diffusion:-direction- the movement of solutes from a greater concentration of solutes to a lesser concentration of solutes; “down the gradient”-rate- to increase rate of diffusion: increase temp, increase concentration gradient, decrease size of particles, decrease viscosity, increase surface area, increase permeability -rate also depends on the state the solution is in: will be faster in gases, slower in solids-viscosity- the thickness of a liquid-permeability- ability to go through something-diffusion can occur across a membrane, but cell membranes are selectively permeable and will allow some things to go through and some things are not-look for proteins that are presentThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. Different Types of DiffusionPassive transport- moves down the gradient; no energy (ATP) is used, instead it is procured fromthe concentration gradient by random thermal movement; for lipid-soluble materials, can go through the lipid bilayer; other materials have to use channels which will allow specific ions and water through-aquaporin—membrane protein that only lets water through-ion channel-channels for a specific ion—show selectivity for the type of ion or ions that can diffuse through them; can only allow monoatomic, not polyatomic ions, through; small size of the channel protein prevents larger molecules from entering or leaving; can be gated-three types of gated channels:-ligand gated-membrane channel operated by the binding of specific molecules to channel proteins-voltage gated-cell membrane ion channel opened or closed by changes in membrane potential-mechanical gated-membrane ion channel that is opened or closed by deformation or stretch of the plasma membrane; does not need to change shape, only distort to open or close channel-Facilitated diffusion-uses a transporter protein to move a solute using a transporter-Transporter-integral membrane protein that mediates passage of molecules through themembrane -transported solute must first bind to a specific site on a transporter, a site exposed to the solute on one surface of the membrane -a portion of the transporter then undergoes a change in shape, exposing this same binding site to the solution on the opposite side of the membrane-also shows chemical specificity-use to move small organic molecules like glucose, amino acids, ions (bicarbonate and phosphate)-bind molecule from outside; potential energy in concentration gradient causes protein to change shape, dump molecule on inside of cell when affinity is lostActive transport-uses energy (ATP) directly or indirectly and allows for movement against the gradient; requires transporters-Primary active transport- transporter (actually an enzyme) called ATPase will catalyze the breakdown of ATP (also called “pumps”); add phosphate group to change the shape of transporter protein—can create a gradient in the process; move Na+, K+, Ca+2, H+--controlled by primary active transport; relatively few ions involved; creates ion gradients Secondary active transport-uses ion gradients from primary active transport for energy (does not use ATP directly); the movement of an ion down its gradient is coupled to the transport of another molecule (glucose or an amino acid); transporters that mediate secondary active transport have two binding sites, one for an ion and another for the cotransported molecule; ion goes down the gradient, cotransported molecule goes against the gradientCoupled transport-types of secondary active transport:-Cotransport-Ion goes into the cell with its gradient, but also transfers something else against the gradient; both ion and other molecule are going into the cell-Countertrasnport-Move ion and transported material in opposite directions; ion is goinginto cell, other molecule is going out of cell—requires specific arrangement of binding sites-Amino acids and glucose can be moved by both facilitated diffusion and secondary active transportIII. Exocytosis and EndocytosisExocytosis-moving a protein out of the cellEndocytosis-uses endocytotic vesicles to move a protein into the cell (proteins can only be moved into the cell if it’s enclosed in a vesicle); different than getting it across the membrane and getting it into the cytosolIV. OsmosisOsmosis is the diffusion of water; have movement of water from a greater concentration of water to a lower concentration of water-OR the movement of water from a lesser concentration of solute to a greater concentration of solutes-Molarity tells us concentration of solutes-Osmolarity-tells us concentrations of solutes in terms of water (the more solute particles you have, the less water); total solute concentration of a solution-ex. 1M glucose = 1 Osm glucose-ex. 1M NaCl = 1M Na+,1M Cl- = 2M particles = 2 Osm NaClV. TonicityTonicity-measure of osmotic pressureIso-means sameHypo-means lessHyper-means moreIsotonic solution-water may move in and out of cell but there is no net movement of waterHypotonic solution-water moves into the cell; causes the cell to swell which, depending on the elasticity of the cell, could cause the cell to break (lysis) Hypertonic solution-water moves out of the cell, causes the cell to shrinkImportant Assumptions to make when measuring tonicity: water can move, solute particles didn’t moveIf something is lipid soluble, you can’t control permeability (membrane is permeable for lipid soluble); but if something is water soluble, we can control permeability.Solutes: penetrating and nonpenetrating-penetrating-go through the membrane (lipids)-nonpenetrating- does not go through the membrane, used to determine tonicityFor tonicity, only look at nonpenetrating solutes.For osmolality, look