bio unit 3 pt 2 (cell membrane transport and nervous system)

fluid mosaic model

the parts that make up the cell membrane, can move around

head of phospholipid

tail of phospholipid

hydrophillic, polar

hydrophobic, non-polar

amphiphilic

head likes water because it is also POLAR WOW

semi-permeable

lets some materials through but not others

aplicable to cell membrane

cholesterol in the phospholipid bilayer

acts as spacers between phospholipids in cold temps

acts as connecters in warm temps

integral proteins

go through membrane - involved in transport, lets things in / keeps things in

transport (channel) proteins

allow only certain molecules to pass through

exclusively involved in passive transport, also known as facilitated diffusion

receptor proteins

receive info from outside the cell and trigger a response inside

marker proteins (glycoproteins)

have carbohydrate chains that act as identifiers to identify cells

passive transport

no energy

moves molecules along (DOWN) concentration gradient

moves small nonpolar and polar molecules

uses: water, oxygen, carbon dioxide, glucose

examples: simple diffusion, facilitated diffusion, osmosis

active transport

uses energy

uses: large and charged particles

moves molecules against (UP) concentration gradient

always involves channel proteins

ions line Na+ and K+

examples: pumps, exocytosis (pinocytosis and phogocytosis), exocytosis

simple diffusion

movement of molecules from high to low concentration (down gradient)

molecules pass between phospholipids

moves small polar and nonpolar molecules

ex: oxygen and carbon

facilitated diffusion

movement from high to low concentration (down gradient)

always involving transport proteins/channel (membrane spanning) proteins

moves small polar and nonpolar molecules

ex: water and glucose

osmosis

the diffusion of water across a membrane though channels called aquaporins

hypotonic

outside has lower solute than inside

water moves into cell

cell swells

hypertonic

outside has higher solute than inside

water moves out of cell

cell shivels

isotonic

solute concentrations are equal

no net movement

what is active transport

movement of molecules from low to high concentration

required energy in the form of ATP

uses transport proteins (often pumps)

proteins pumps

use energy to push molecules against their concentration gradient

uses energy released within cells to force substances through the plasma membrane

endocytosis

cell taking materials in

phagocytosis and pinocytosis

phagocytosis

cell eating (large particles)

• Movement of large food particles across the membrane with the use of pseudopods

pinocytosis

cell drinking (small dissolved molecules)

exocytosis

cell gets rid of particles by fusing a vesicle with the cell membrane

how are the bubbles similar to cell membranes

hydrophilic head and hydrophobic tail

how are the bubbles different from cell membranes

the surrounding medium (air) is non polar so the tails of the bilayer face outward and the heads form the inside with a thin layer of film of water

what is the function of the cell membrane

separates the contents of the cell from the surroundings, serves as a barrier for which substances can enter and exit a cell, recognizes chemical signals which will trigger the cell to react in a particular way

peripheral proteins

more loosly attached, act as enzymes, help with cell shape

glycoproteins

proteins and carb bound

identifies cell as part of the organism

glycolipids

carbs and phospholipids

communcation

ion channel

protein that acts as a pore to ions - allows them to pass freely through plasma membrane in either direction

aquaporin

pores made of protein, allows for water molecules to pass easily through cells plasma membrane

oxygen

concentration of oxygen in the cell is lower than the outside

passes from high to low - into the cell (diffusion)

carbon dioxide

higher concentration of carbon dioxide in the cell

passes from high to low - out of the cell (diffusion)

sodium

protein pumps

water

can pass through lipid bilayer (slower) OR with aquaporins (faster)

enzymes

exported through exocytosis process (surrounds enzyme and releases it out of the cell)

potassium and sodium

passive (facilitated diffusion) and active (pumps out of cell)

hypotonic vs hypertonic

hypotonic = the solution has less solute than the cell, so water will flow from the solution into the cell (down the gradient, high to low), causing it to swell hypertonic = the solution has more solute than the cell, so water will flow from the cell into the solution, causing it to shrink