chapter 5


  • Endomembrane system (and it’s components)

    • Structure and functions of ribosomes, ER, golgi, and vesicles

  • group of membranes & organelles that work together to synthesize, modify, package, and transport proteins and lipids using:

  • ribosomes: synthesize protein

  • endoplasmic reticulum: fold and modify protein

  • golgi apparatus: sort and package protein

  • golgi vesicle: transport protein to target destination


  • Bilayer structure (what is it made from?)

    • Phospholipids (structure and functions)

  • major component of plasma membrane

  • can move around within the bilayer

  • hydrophobic tail, hydrophilic head

  • Proteins (integral vs peripheral) 

  • integral: span the entire bilayer moving things in/out

  • peripheral: either on exterior or interior surface (usually enzymes or structural attachments)

  • Carbohydrates (glycoproteins, glycolipids)

  • bound to protein → glycoproteins

  • bound to lipids → glycolipids

  • Role in virus attachment and treatment (very basics, nothing specific)

  • Fluidity (effects of temp, cholesterol, and unsat vs sat fats)

    • Cholesterol (what does it do and why is that important?)

  • randomly distributed across the bilayer, helping it stay fluid.

  • increases fluidity at low temps and decreases fluidity at high temps

  • Temperature (what happens when it’s hot vs when it’s cold?)

  • colder= closer phospholipids → restricts small molecules 

  • warmer= more separated phospholipids —> leaves larger gaps

  • Fats: unsat. vs sat. (how do they each affect the membrane?) 

  • - saturated are straight, easy to pack tight,

  • unsaturated fats have double bonds that create kinks in the chains, making it more fluid. 

  • Understand what selective permeability means 

  • allows some substances to cross more easily.

  • What type of molecules get in easy and what type don’t (see slide titled “The Permeability of the Lipid bilayer, should be #51)

  • small & non polar molecules: pass easily and quickly. do not require proteins for transport

  • small & polar molecules: more difficult than non polar: hydrophobic tails of the bilayer makes it tougher and slower, but can cross without the help of proteins

  • large & nonpolar molecules: can pass but it is a slow process

  • large & polar molecules: too difficult to pass  through without help due to their size and charges (ions).

  • 4 methods of stuff getting into and out of a cell (passive vs active transport)

    • Passive Transport- Diffusion (no energy input):

  • solute moving from areas of high concentration to areas of low concentration


  • Passive Transport (no energy input)- Osmosis : 

  • the movement of water. water molecules from areas of low concentrations to high solute concentration

  • balance by increasing water

  • Tonicity (Hypo, hyper, isotonic), turgor pressure, how water moves (see slide 60)

  • tonicity is the ability of a solution to cause a cell to lose or gain water

isotonic solution: concentration of solutes is the same inside and outside of the cell

hypotonic solution: hypo= less. less in the solution than in the cell. water will rush into the cell. cell will EXPAND

hypertonic solution:hyper= more. more in the solution than in the cell, water will rush out of the cell. the cell may shrink. 


  • Passive: Facilitated Transport/Diffusion:

moves substances down their concentration gradient (high → low concentration)

  • requires the use of transmembrane proteins: Protein channel and carrier proteins (water channels: aquaporins)

channel proteins: (less specific) only “appropriate” molecules pass into and out of the cell. some are open all the time, some are only open when a signal is received. 

carrier proteins: (more specific) specific to a single substance. (binds to that substance, changes shape, carries to the other side).


  • What affects which molecules channel proteins allow in?  size and charge of molecules. 

  • Active: Active Transport: what is it and what does it require? 

  • must be against its concentration gradient (low to high)

  • energy is ALWAYS required

  • The Sodium-Potassium Pump basics, slide 71 offers a great, quick but thorough review 

  • Bulk Transport

    • Exocytosis: what is it and what happens? 


  • ex= “out”, cytosis= “cell process”

  • transport vesicles containing substances to be secreted fuse with the plasma membrane

  • content are then released outside of the cell into the extracellular fluid

  • Endocytosis

  • endo= “in”, cytosis “cell process”

  • vesicles are formed from the plasma membrane and bring molecules INTO the cells for various functions

  • Phagocytosis – “To eat” – engulfment of food/pathogen

  • Pinocytosis – “To drink” – usually involving extracellular fluid

  • Receptor Mediated – Highly specific, coated vesicles (i.e. cholesterol), locking key