Warm-up

• Why is it important to regulate what comes into or goes out of a cell?

Cell Boundaries

Cell Membrane

• Composed of the lipid bilayer– Double layered sheet of lipids (fats) that

encompasses the whole cell– Also found in mitochondria, golgi apparatus,

nucleus, lysosomes– Allows cell to be fluid (able to flex and move)

Cell Membrane

• Contains hydrophillic heads and hydrophobic tails

• Protein channels are embedded in membrane, as are protein pumps

• Carbohydrates attached function as a signal to other cells

Cell Wall

• Found in plants, fungi, and prokaryotes• Located outside the plasma membrane• Composed of cellulose fibers (in plants)

Diffusion

• Movement of molecules from an area of high concentration to low concentration– Air freshener– Food coloring

• Molecules will move until equilibrium has been reached (equal amounts everywhere)

• Important for cell functions in the body• Works without an input of energy

Osmosis

• Movement of water across a semi permeable membrane– Allows water to flow into and out of a cell, but

keeps most other substances out

Osmotic Pressure

• Pressure exerted on a cell from the hypertonic side of a semi permeable membrane

• Without any protection, cells would burst under osmotic pressure in presence of fresh water

• Plant cells and bacterial cells are in the presence of fresh water, but do not burst

Facilitated Diffusion

• Helps molecules pass through the cell membrane

• Works through protein channels– Allows molecules such as glucose, sodium,

potassium, and calcium to enter and exit a cell• Works through a gradient (no input of energy

required)

Active Transport

• Movement of molecules against a gradient (requires energy input)

• Works through protein pumps, endocyotosis and exocytosis

Endocytosis

• Taking materials into a cell• Creates a vesicle from existing plasma

membrane that engulfs the material

Phagocytosis

• Refers to a cell consuming food/nutrients needed for survival

• Functions in the same way as endocytosis

Pinocytosis

• Uptaking of water from the environment• Functions the same way as endocytosis

Exocytosis

• The releasing of material from a cell• Cell membrane creates a vesicle that stores

the material, then the vesicle leaves the cell

Activity

• Make foldable. On one flap, explain the differences between a cell membrane and cell wall (functions as well). On the second flap, compare and contrast facilitated diffusion with active transport (give an example of each one in the body). On the third flap, draw a picture of endocytosis and exocytosis, then explain what each one is.