Plasma Membrane

Plasma Membrane = Lipid ( cholesterol, phospholipid, glycolipids ) + Protein ( ID, enzymes, receptors, channels, carriers, cytoskeleton )

• each molecule consists of a hydrophilic (water-loving) portion and a hydrophobic
• (water-hating) portion. Due to the amphipathic nature and insolubility
• in water, phospholipids are ideal compounds for forming the biological
• membrane.
• The fatty acid part minimize interaction with the water because it is
• hydrophobic which is non polar. While the Hyrdophilic head (polar) is
• faced outward because it loves water.

Allows some things to go in/out depending on phosphilipid properties.

Sideways motion of proteins/fats across plasma membrane.

• For selective permeability, Small, uncharged and non-polar molecules can get across.Large polar molecules and ions can't get across.
• Reduced fluidity= making all fatty acids saturated .Increase Fluidity= fatty acids have to be unsaturated

• - cell division ex. cytokinesis
• - medicine ex. artifical fertilization

• They change the fat content of the plasma membranes.
• Increase fluidity= increase the amount of saturated fatty acids, reduces fluidity, make fat saturated ( hot summer )
• Decrease fluidity= ( membrane can freeze ) -> increases the amount of unsaturated fatty acids ( cold winter )

• 20% of plasma membrane.
• - it resist chanes in fluidity
• - it strengthens plasma membrane
• At warm temperatures, cholesterol restrains the movement of phospholipidsand reduces fluidity
• .• At cool temperatures, cholesterol maintains fluidity by preventing tight packing.

• " nametags" of the cell, identiflies cells, cell identity markers
• ex. organ transplant ( liver, heart,lungs,lens of eye,skin) why is it rejected sometimes?
• Its because of the differences in glycolipid

• Transport proteins: movement of specific substances into or out of cells-
• Enzymes, sometimes catalyzing one of a number of steps of a metabolic pathway-
• Receptors, which relay hormonal messages to the cell
• Cytoskeleton anchors
• Identity markers

• Cause: affects plasma protein, pancreas doesnt produce enough insulin, # of glucose carriers drops, blood sugar levels go up
• Cosequences: cells starve, can't get sugars in cell, high sugar levels in urine

• The position of the proteins along the plasma membrane serves a purpose
• as they function in anchoring the cytoskeleton within the cell. The
• cytoskeleton gives the specific structural shape to the cells, which
• ranges from the simple disc shaped red blood cells to the complex
• structure of neurons.

• web like arrangement of membrane proteins that encircle the cell
• Function : prevents leakages of fluids btwn cells

• " cytoplasmic " connections btwn plant cells.
• it allows communication btwn cells

• localized, protein linkages that are reinforced by intermediate fibers.
• it anchors and prevents cells from falling apart

• are open protein channels btwn cells.
• They allow for cells to communicate.
• Important for food to be moved down to stomach
• ex. peristalisis

• Passive: High to low conc. requires no energy(ATP), concentration gradient
• Active: Low to high conc. Requires ATP, protein->pump, against conc. gradient

• DIFFUSION:the process
• by which molecules spread from areas of high concentratiion, to areas
• of low concentration

facilitated diffusion:"needs help" needs an ion pump or a protein channel

Plasma membrane transport= Passive ( diffusion, facilitated diffusion, osmosis ) + Active ( primary, secondary, bulk )

• form of diffusion.
• passage of free water from low solute to high solute conc. across a selected permeable membrane.

• inverse relationship
• The more solute, the more it reduces the # of free water molecules.

• a form of malnutrition caused by inadequate protein intake
• - rejected ones, mother stopes breast feeding them
• - stops taking in milk, stops taking in protein(solute)

• hypotonic: high solute conc around cell than inside cell ( free water comes out, inside cell will swivle )
• Isotonic: same solute conc. inside and outside cell ( animal cells do well )
• Hypertonic: lower solute conc. compared to within cell ( plant cells do well )

• Animal cell=
• Hypotonic: Lysis, bursts/destruction
• Isotonic: normal
• Hypertonic: Crenation

• Plant cell=
• 

• all use energy in form of ATP, use membrane protein, moving things against
• conc, gradient, low to high conc.

• also called direct active transport, directly uses energy to transport molecules across a membrane
• It expends ATP energy to move sodium ions out of the cell and replace them with potassium ions.
• outside= more positive , inside= more negative
• every 3NA+ pumped out for 2K+ pumped in
• 

• -use of ATP indirectly
• -cotransporter=moving H+ and sucrose at the same time b/c we are using hydrogen ion conc. difference
• -Exchangers move two or more molecules in opposite directions. ( Na and H )

• it is most inportant pump in body, its how electrical signals happens in brain and nerves
• - for nerve impulses

• -cant find cyanide in blood, only through hair folicles
• -The cyanide shuts off the power generater of cell
• -pumps shut off (Na+ dont go out and K+ dont go in anymore )
• - charge difference dissapears and then heart muscles and brain stops

movements of large amount of substance in/out of cell all at once; using vesicles

• endocytosis: , the cell engulfs some of its extracellular fluid (ECF) including material dissolved or suspended in it.
• exocytosis: is a cellular process where cells eject waste products or chemical
• transmitters (such as hormones) from the interior of the cell

Phagocytosis: selective Cell eats(ingulfs) large particles ex. backteria, food particle

Pinocytosis: non-selective, no receptors, cell bringing in fluids with dissolved particles inwards

Receptor-mediated endocytosis: selective, receptor involed, bulges inwards, brings in dissolved fluids and vitamins