bio - cell transport + diffusion/osmosis

homeostasis

the tendency toward a relatively stable __equilibrium__ between elements

diffusion

a physical process where molecules of material move from an area of high concentration (many molecules) to an area of low concentration (fewer molecules). 

osmosis

The movement of water into or out of the cell (HIGH to LOW concentration)

facilitated diffusion

when a protein helps move specific molecules across the membrane (transports larger or charged molecules)

passive transport

simple diffusion, no energy required to move molecules (HIGH to LOW concentration across the bilayer)

active transport

the cell uses energy to transport large molecules from LOW to HIGH concentration

cell transport

The movement of substances across the cell membrane to either in or out of the cell. 

isotonic

in the middle, equal (salt) concentration (moves in both directions)

hypertonic

much more salty compared to the cell (water diffuses OUT - cell looks shriveled up) - (HIGHER to LOWER concentration)

hypotonic

much more watery compared to the cell (water diffuses IN - cell looks v. thicc) - (LOWER to HIGHER concentration)

plasma membrane

controls the movement of molecules into or out of the cell (made up of lipids and proteins -- see the Fluid Mosaic Model)

absorption

materials enter the cell

circulation

materials are moved throughout the cell

cyclosis

the circulation of the cytoplasm

cholesterol

gives the membrane a more rigid structure

proteins

Integral/transmembrane proteins are embedded in the bilayer

carbohydrates

may function in a cell’s ability to distinguish one type of neighboring cell from another (Cell to Cell Recognition)

diffusion, facilitated diffusion, osmosis

three types of passive transport

molecules able to diffuse

nonpolar molecules and polar molecules that are **small enough** to fit through the selectively permeable membrane

dynamic equilibrium

molecules that become evenly distributed - the molecules are still in motion, but the same number of molecules move in one direction as in the opposite.

osmoregulation

the control of the levels of water and mineral salts in body fluids to maintain homeostasis -- keeps the body’s fluids from becoming too dilute or too concentrated

protein pumps

transport proteins that require energy to work

endocytosis

forming vesicles to bring molecules into a cell

phagocytosis

“cellular eating”. false limb-like structures (pseudopods) are formed and the particle is engulfed and digested within a lysosome

receptor-mediated endocytosis

a type of endocytosis where specific molecules are ingested into the cell. the molecules bind to the receptor ONLY IF the shapes match.

exocytosis

intracellular vesicle moves to the plasma membrane and fuses with it to spill the contents outside of the cell

transport proteins

help to move molecules in or out

receptor proteins

attract specific molecules to the membrane to initiate transport

how do organisms function?

bacteria and plants have cell walls that prevent them from over-expanding. in plants the pressure exerted on the cell wall is called turgor pressure.

pinocytosis

“cell drinking”. dissolved materials are taken in when the cell membrane dips inward and pinches off to form a vesicle around it.