AP BIO UNIT 2.4-2.9

peripheral proteins

loosely bounded on the surface (hydrophilic with charged polar and side groups)

integral proteins

span membrane, hydrophilic and hydrophobic (non polar penetrate hydrophobic interior)

list membrane protein functions

1. transport

2. cell-cell recognition

3. enzymatic activity

4. signal transduction

5. intracellular joining

6. attachment for cytoskeleton

fluid-mosaic model

structured as mosaic of protein molecules in fluid phospholipid bilayer

cholesterol

randomly distributed among phospholipids, regulates bilayer fluidity in different environmental conditions

carbohydrates

function as markers

• glycoprotein, glycolipids (cell recognition)

what can pass through the membrane on its own

small non polar molecules, small polar molecules (AT MINIMAL AMTS)

what type of molecules need transport proteins

hydrophilic large polar ions

channel proteins

hydrophilic tunnel spanning membrane that allows specific target molecules to pass

carrier protein

span membrane, changes shape to move target from one side to the other

plasmodesmata

small holes between plant cells that allows for transfer of nutrients, wastes and ions

endocytosis

requires energy to move large molecules in cell

exocytosis

requires energy to move large molecules out of the cell

phagocytosis

cell takes in large particles

pinocytosis

cell takes in extracellular fluid containing dissolved substances

cotransport

secondary active transport that uses energy from electrochemical gradient to transport two different ions across membrane through protein

symport

two different ions are transported in same direction

antiport

two different ions are transported in opposite directions

osmosis

diffusion of free water across selectively permeable membrane (largely through aquaporins)

osmolarity

total solute in solution

tonicity

measurement of relative concentration of solute between 2 solutions

hypertonic

solute > solvent

isotonic

solute=solvent

hypotonic

solute<solvent

what way does water move?

towards region with higher solute concentration

osmoregulation

maintains water balance and control of internal solute composition / water potential

environmental hypertonicity in plant cells

less solute + more water (water leaves plant cells)—> plasmolysis (shrinks)

environmental hypertonicity in animal cells

less solute + more water (water leaves) —> shriveled

isotonic solution in plant cells

equal solute + water —> flaccid (normal)

isotonic solution in animal cells

equal solute + water —> normal

environmental hypotonicity in plant cells

more solute + less water —> turgid (swollen vacuole) + happy plant

cell wall maintains homeostasis for plant in hypotonicity —> osmotic pressure is high outside the cell, water flows into vacuoles via osmosis

cell wall expands until pressure is exerted back on the cells (turgor pressure)

environmental hypotonicity in animal cells

more solute + less water —> lysed

bloats the cell and explodes/bursts