Cellular membranes (incl. plasma membrane)

	Fluid mosaic model Phospholipid bilayer with imbedded proteins and hybrid molecules Cholesterol (among phospholipid tails) stabilizes membrane Rafts Linked groups of membrane molecules that travel together like a raft within the fluid bilayer
	Functions - see table in Chapter 3   ANIM Cell membrane functions are cell functions (many functions of cells that we will discuss are in reality jobs performed by the membranes of cells)

Other important basic cell structures

	Nucleus Nuclear envelope Nuclear pores Nuclear pore complex (NPC) is the specific structure at each opening in the nuclear envelope Nucleoplasm Chromatin DNA plus protein  Chromosome = condensed chromatin Primary genetic code of the cell Click here  ANIM to see a slick view of DNA that will help you understand where it is and what it is Nucleolus - forms ribosome parts (rRNA)
	Mitochondrion (pl. mitochondria) Double membrane - inner membrane folded into cristae Involved in transfer of energy from fuel molecules to ATP Serial Endosymbiosis Theory - SET (Lynn Margulis)   pp Required Mini Lesson SET and Organelles
	Ribosome Assembled as subunits of rRNA/protein in nucleolus Attach to mRNA strands (containing a gene) to guide assembly of amino acids into a polypeptide or protein Amino acids are brought to the ribosome by tRNA

Transport concepts    pp

Passive forms of transport -- do not require cell expenditure of energy Particles move down their concentration gradient That is, particles move from area of high concentration to area of low concentration If possible, particles eventually reach a dynamic equilibrium in which there is no difference in concentration Simple diffusion ANIM Particles pass through cell membrane as they diffuse down their concentration gradient Depends on how membrane-soluble the particles are Mediated transport (not-so-simple diffusion)    pp Channel-mediated passive transport Particles diffuse through membrane channels Carrier-mediated passive transport    ANIM Particles diffuse through carrier mechanisms in a membrane Also called facilitated diffusion Osmosis - diffusion of water in presence of impermeant solutes     pp Osmotic pressure (actual vs. potential)    pp Isotonic - solution with same potential osmotic pressure as another solution There is no net water movement between isotonic solutions    pp Hypertonic - solution with higher potential osmotic pressure than another solution There is net movement of water INTO a hypertonic solution Hypotonic - solution with lower potential osmotic pressure than another solution There is net movement of water OUT OF a hypotonic solution

Active forms of transport -- require cell expenditure of energy Ion pumps ("active transport")   ANIM     pp Particles are moved up their concentration gradient Pumps are carriers that use energy transferred from ATP Cotransport Particles are moved in the same direction by the same mechanism Also called symport   ANIM Countertransport Particles are moved in opposite directions by the same mechanism Also called counterport or antiport     ANIM Bulk transport by vesicles Exocytosis   ANIM Moves large number of molecules OUT OF a cell Internal vesicle moves to plasma membrane and "pops open" releasing material from vesicle Endocytosis   ANIM Moves large number of molecules INTO cell Plasma membrane pinches in, trapping extracellular material into a vesicle Two types: Phagocytosis     ANIM Chunks are brought into cell (literally, "cell eating") Pinocytosis Fluids are brought into cell (literally, "cell drinking")