Chapter 3 notes continued (osmosis and active transport and membrane proteins

Osmosis is the __________ diffusion of water

Passive

Osmosis is important in determining _________

distribution of water in and outside of cells

Water can move directly through _________ due to _____ size

plasma membrane, small

Aquaporins

water specific transmembrane proteins; abundant in RBCs and kidney tubule cells

osmolarity

total concentration of solute molecules in solution

osmotic pressure

tendency of water to move into a cell

toncity

ability of solution to change in shape of cell due to movement of water, important to RBCs

Isotonic Solution

cells retain their normal size and shape

Hypertonic Solution

cells lose water and shrink

Hypotonic Solution

cells take on water until they become bloated and burst

Active transport requires ______

transport protein and energy input

In active transport the solute moves low to high concentrations ______________-

, “against the concentration gradient.”

There are two types of active transport ________________

primary active transport and secondary active transport

Primary Active Transport

-energy from hydrolysis of ATP, protein changes shape to move substance across membrane

Secondary Active Transport

energy comes from the substance moving down the gradient, “dragging” along the substance moving against its gradient

Contransport

moves two different substances in the same direction

Vesicular Transport” Endocytosis

moves solids and fluids into cell in vesicle (membrane bound sac)

Phagocytosis

cell engulfs large, solid molecule in phagosome, performed by macrophages

Pinocytosis

cell engulfs fluid and dissolved particles; routine activity performed by most cells

Vesicular Transport: Exocytosis

moves substance out of cell in secretory vesicle

vesicular transport , mechanism for secreting _______

hormones, nuerotransmitters, mucus, or ejecting waste

vesicular transport, secretory vesicle fuses with _______

cell membrane and ruptures, releasing contents into extracellular space