Biology unit 3: A Closer Look at the Plasma Membrane

Plasma Membrane

-known as a lipid bilayer or fluid mosaic

-boundary between inside/outside

-semi- or selectively permeable

Phosphate Heads

”hydrophilic”

Fatty Acids Tails

”hydrophobic”

Carbohydrates

chain cell-to-cell communication and ID

Cholestrol

stabilizes membrane and keep it fluid

Transport Proteins

Integral Proteins and Peripheral Proteins

Integral Proteins

span all the way across membrane

-hallway-transport stuff

Peripheral Proteins

move molecules integral proteins

Passive Transport

-requires no ENERGY (No ATP)

-particles move from HIGH to LOW concentration

-with the flow

Active Transport

-requires energy (ATP)

-moves from LOW to HIGH concentration

-against the flow

Concentration

number of particles in an area

Concentration Gradient

Difference in concentration across a membrane

Solute

Particles in a mixture (salt, sugar, etc)

Solvent

Almost always water

Diffusion

Movement of particles across a membrane from HIGH to LOW concentration

“With the concentration Gradient”

Facilitated Diffusion

-diffusion helped by transport proteins

Osmosis

diffusion of water across a membrane

Rate of diffusion

-faster w/ higher temps (molecular movement) affects rate

Real life Diffusion

-fragrance spreads on its own

-O2 into bloodstream

-CO2 into lungs