Ch. 5 Structure and Function of Plasma Membranes

Phospholipids

amphipathic molecules (partially hydrophobic and partially hydrophilic)

phospholipid equation

1 glycerol and 3 OH + OH and 1 fatty acid -> 1 gylcerol, 3 O, 2 fatty acids, and 1 phosphate + 3 H2O

Phospholipid tail is

hydrophobic

Phospholipid head is

hydrophilic

T/F any ion will like water (hydrophilic)

True

All cell membranes are composed of

phospholipids

T/F in water, phospholipids form a bilayer

True

T/F all cell membranes have a phospholipid bilayer

True

fluid mosaic model

All cell membranes are a phospholipid bilayer (fluid) with other components inserted (mosaic)

Diffusion

The net movement of molecules from their own area of high concentration to their area of low concentration

Rate of diffusion is affected by

Temp, size of gradient, distance of gradient, mass of molecules, density of medium, pressure

selectively permeable

Only some molecules are free to diffuse across

T/F phospholipid bilayers are selectively permeable

True

Molecules that are free to diffuse

Water, gases, small hydrophobic molecules

Another name for selectively permeable

semipermeable

Osmosis

Diffusion of WATER across a selectively permeable membrane

hypertonic solution

Higher salt concentration than the intracellular environment

Where is the movement of water in a hypertonic solution

Across the membrane to the extracellular solution

Isotonic solution

Same salt concentration as the intracellular environment

Where is the movement of water in an isotonic solution

No net movement

hypotonic solution

A lower salt concentration than the intracellular environment

Where is the movement of water in a hypotonic solution

Across the membrane to the intracellular solution

facilitated diffusion

Transmembrane proteins called channels or carriers allow for the diffusion of select molecules or ions across the membrane

active transport

Transmembrane proteins called PUMPS move molecules or ions against their gradient (low to high)

coupled transport

Two molecules or ions are brought through the same transmembrane proteins (symport = same direction, antiport = opposite direction)

Conditions for coupled transport

First molecule diffuses (high to low), second molecule goes against the gradient (low to high)

T/F energy is spent during coupled transport

False (second molecule uses the energy of diffuse from the first molecule)

Another name for coupled transport

Cotransport

Endocytosis

Larger molecules, groups of molecules or even cells are transported into the cell by this process

Is endocytosis active or passive?

active

Other names for endocytosis

Phagocytosis, pinocytosis

Exocytosis

Larger molecules and groups of molecules are transported out of the cell by this process

Is exocytosis passive or active

active