THE CELL Membrane Notebook Page 33 & 34

Cell Membrane Also called the Plasma Membrane

1. Made of phospholipid bilayer hydrophobictails a. hydrophobic tails (repels water) point inward Chains of fatty acids b. hydrophilic heads b. hydrophilic heads (attracts water) point outward Made of an alcohol and glycerol Fluid Mosaic Model

The phospholipids can move sideways to allow water and other Non-Polar molecules to pass through into or out of the cell

A. Passive Transport 1. requires no energy 2. occurs with the concentration gradient 3 examples Membrane Transport a. Diffusion

Made of proteins, carbohydrates and cholesterol Fluid Mosaic Model

a. Cholesterol mc Fluid Mosaic Model Fluid Mosaic Model are scattered throughout membrane help stabilize membrane Make the membrane more fluid 1. Cholesterol – another type of lipid In the cell membrane

Proteins Proteins functions

Proteins 1) Kinds: 1) Kinds: Proteins, carbohydrates and cholesterol Integral Integral Or Or transmembrane proteins Go all the way through Peripheral Peripheral Only on one side

Large molecules Like proteins or carbohydrates use proteins to help move across cell membranes. Some of the membrane protein have carbohydrate parts attached to help cells recognize each other and certain molecules

Cell Membrane 1.Cell Signaling 2. Selective transport 3. Excretion of wastes 4. Structural support Function Function

Membrane Permeability Membrane Permeability Selectively permeable Membrane Transport Membrane Transport

examples Osmosis - diffusion of water Water moves from high water (low solute) concentration to low water. Moving down with the concentration gradient

Important Terms Hypotonic Solution has lower % solute than the cell; water moves into the cell

HypertonicHypertonic Solution has higher % solute than the cell; water moves out of the cell Important Terms Hypotonic

HypertonicHypertonic IsotonicIsotonic Solution has same % solute as the cell; water movement in = out Important Terms Hypotonic

Water movement

Passive Transport - no energy required examples Facilitated diffusion uses membrane proteins example: glucose is carried by permease

Predict the Result of Facilitated Diffusion

Passive Transport examples Filtration Occurs when pressure is exerted on the fluids and solutes Kidneys Dialysis

Active Transport 1.requires energy – ATP 2. movement of mc against the concentration gradient Uses 40% of ATP in cell!

Kinds of Active Transport Sodium Potassium pump move ions into and out of the cell against their gradients move ions into and out of the cell against their gradients Helps muscle cells contract

Active Transport Pumps Transmembrane /intregral proteins – Change shape to move ions

3. Kinds of Active Transport b. Vesicular transport 1) Endocytosis

phagocytosis – “cell eating”, pinocytosis - “cell drinking” Endocytosis Endocytosis

Kinds of Active Transport Vesicular transport Kinds of Active Transport Vesicular transportexocytosis