The Plasma Membrane and Cell Transport Biology Sections

The Plasma Membrane and Cell Transport Biology Sections 7. 2 and 8. 1

Plasma Membrane G Plasma membrane - flexible boundary between a cell and its environment. Inside Cell Outside Cell

What is the nickname of the Plasma Membrane? The “Gate Keeper” Because it maintains homeostasis by controlling what enters and leaves the cell.

What does selectively permeable mean? G Membrane allows some molecules to pass while keeping others out. G Kind of like the screen on your window.

Structure of the Plasma Membrane. G Made of phospholipids like the one below:

Phospholipid G Phospholipid is made of glycerol backbone, two fatty acid tails and a phosphate group. Glycerol Backbone Nonpolar tails (fatty acids) Polar head (includes phosphate group)

Phosholipid Bilayer G There are two layers of phospholipids back to back, making the plasma membrane a phospholipid bilayer.

Model of the Plasma Membrane G Fluid Mosaic Model

What can be found in the Plasma Membrane G Proteins (Transport Proteins) G Cholesterol - for stabilizing the phospholipids. G Carbohydrates - identify chemical signals.

Transport Proteins

Cholesterol

Carbohydrates

Plasma Membrane Activity Color/draw the plasma membrane.

Transport Across the Plasma Membrane G 2 Main Types 1. Passive Transport G G Moves things with their concentration gradient. No energy needed! 2. Active Transport G G Moves things against their concentration gradient. Requires energy!

What is a concentration gradient?

Passive Transport Moves things from high to low concentration. G Diffusion - simple movement from high to low concentration. No ENERGY required! G Osmosis - diffusion of water across a selectively permeable membrane. (No ENERGY required!) G Facilitated Diffusion - passive transport using a channel or carrier protein. (still does not require energy)

Diffusion

Osmosis

Osmotic Pressure

Turgor Pressure - pressure of the water in a full vacuole of a plant cell against the cell wall.

Active Transport G Protein pump used to move particles from low to high concentration.

Na+ K+

Transport of Large Particles G Endocytosis - process by which a cell surrounds and takes in material. (Requires ENERGY) G Exocytosis - the explusion or secretion of a material from a cell. (Requires ENERGY)

Endocytosis

Exocytosis