Bell Work1. If a membrane allows movement of only certain materials, it is called ___.a.Somewhat permeableb.Selectively permeablec.Somewhat impermeabled.Selectively permeable

Notes: Cell Membrane• Cell membranes are also called plasma

membranes• Facts:– Selectively permeable

• Allows certain materials to move in and out of the cell when needed, but keeps other material from crossing the membrane

– Made of phospholipid bilayer• Water soluble phosphate head (hydrophilic)• Water insoluble fatty acid tail (hydrophobic)

– Has various carbohydrates, proteins and cholesterol mixed into the bilayer

Question1. Which of these is NOT a type of cellular transport?a.endocytosisb.exocytosisc.diffusiond.nucleocytosis

Question2. The cell membrane is made primarily of ___.a.carbohydratesb.Nucleic acidsc.proteinsd.phospholipids

Question3. When active transport is used, the cell ______.a.Does not use any of its own energyb.Uses some of its own energyc.Uses energy from other cellsd.Uses the energy stored mainly in the nucleus

Question

4. During passive transport, a cell ________.a. Does not use any of its own energyb. Uses some of its own energyc. Uses energy from other cellsd. Uses the energy stored mainly in the nucleus

Notes: Cellular Transport

• Diffusion– Movement of molecules from an area of higher

concentration to an area of lower concentration.• Passive Transport– It does not require energy»Oxygen and Carbon Dioxide use diffusion » Not all molecules can enter and leave by

diffuison»Once equilibrium is reached they stop

Notes: Cellular Transport

Concentration Gradient– The name of the difference that exist when there

is a difference in concentration in two areas

Equilibrium– When the concentration on both sides of the cell

membrane are equal

Draw Concentration Gradient

Notes: Facilitated Diffusion

• Transport Proteins– Allow some of the ions, sugars, and amino acids to

pass through from an area of high concentration to an area of low concentration

– Many different types– Each selective for a specific molecule– Form of PASSIVE TRANSPORT

Questions

Why is diffusion a type of passive transport?•A. It moves materials across a cell membrane•B. It does not require any of the cell’s energy•C. It does not need activation by an enzyme•D. It continues until equilibrium is reached

Questions

During diffusion, molecules move _____.•A. from an area of higher concentration to an area of lower concentration•B. from an area of lower concentration to an area of higher concentration•C. across a cell membrane with the use of cellular energy•D. against a concentration gradient

Notes: Osmosis

• Osmosis– Passive transport– Moves molecules down a concentration gradient

• 2 Facts– Always a movement of water molecules– Moves water molecules across a selectively

permeable membrane through which the solute (dissolved particles) cannot cross

Notes: Osmosis

• Osmosis– Solute particles are too large to pass through the

selectively permeable membrane• Like oil and water’s inability to mix, particles that are

water soluble cannot pass through the middle of the membrane– To bring about equilibrium, either facilitated diffusion or

osmosis must take place

Notes: Isotonic Solution

• Isotonic– The solution on the outside of the membrane has

the same concentration as the solution on the inside of the membrane

– No net movement of water molecules across the membrane

Notes: Hypertonic Solution

• Hypertonic– The solution outside the membrane contains less

water and more solute than the solution inside the membrane• water rushes out of the cell• Cell shrivels up• Example: salt on a slug

Notes: Hypotonic Solution

• Hypotonic– Solution on the outside of the cell membrane has

a greater concentration of molecules than the solution inside the cell• More water on the outside• Ex. Wilted vegetable (celery)• Water rushes in an the cells swell

Notes: Active Transport

• Active Transport– Used to move molecules against a concentration

gradient– Requires Energy

• 3 Types of Transport Proteins help move substances in and out of the cellchannel proteinscarrier proteinsgate proteins

Notes: Transport Proteins

• Often the protein has a certain shape that allows it to stick to a molecule with a matching shape

• Uses chemical energy to move against the gradient

Notes: Endocytosis

• Endocytosis– A way of allowing particles that are too big to

cross the cell member to enter– Particle is enclosed with material from the cell,

then pulled into the cell– In = En• Into the cell = ENDOcytosis

Notes: Exocytosis

• Exocytosis– Used to get rid of large particles• Undigested food, waste products or hormones

– Material is enclosed in a vesicle• Vesicle meets the cell membrane, breaks open, then

fuses with the membrane• Particles are released to the outside of the cell

Exit the cell = EXocytosis