Structure (Plasma Membrane) Cell Membrane (Plasma Membrane) Structure A lipid bilayer(2 layers of lipids) with a variety of proteins

Proteins Lipid molecule

Identify the lipid molecules. Identify the protein molecules. Go to Membrane Diagram Identify the lipid molecules. Identify the protein molecules. What is a ‘lipid bilayer’?

-To be Selective Permeable: = Cell Membrane (Plasma Membrane) Function -Helps maintain Homeostasis: = maintain a stable internal environment -To be Selective Permeable: = control what passes in or out of the cell

Cell Membrane What the lipids do… -Act as a lining, separates the chemicals of the cytoplasm from the surroundings

All to move molecules in & out of the cell! Cell Membrane (Plasma Membrane) What the proteins do… . 1. Form a. open channels b. gated channels c. active transport pathways, All to move molecules in & out of the cell!

Ex. 1 of channel proteins. Open channels

Ex. 2 of channel proteins. Gated channel

-Receptors that change cellular activity. Cell Membrane (Plasma Membrane) Protein Function #2 -Receptors that change cellular activity.

Signal molecule Receptor protein

Change cellular activity

Protein Function #3 (Plasma Membrane) Cell Membrane (Plasma Membrane) Protein Function #3 -Create a molecular mark (signature) that identifies that specific, individual cell.

Recognition protein

LOOK!

Types of particle that might cross membranes. Tiny molecules, like… Water Oxygen & Carbon dioxide

Types of particle that might cross membranes. Small molecules, like… Glucose, amino acids, fatty acids and glycerol

Carbon Dioxide Oxygen Water Amino acid Glycerol Glucose Fatty Acid

Yet more types of particles that might cross cell membranes! Yes, even large molecules, such as… Polysaccharides Lipids & proteins!

Lipid soluble molecules Fats, Fatty acids

Charged particles ions Na+, K+, Cl+

Such as… small organisms and Organic debris Even Large Particles may sometimes cross the selectively permeable cell membrane! Such as… small organisms and Organic debris

Diffusion Movement of particles from an area of high concentration to an area of lower concentration.

Diffusion requires a Concentration gradient When the concentration of particles is not the same throughout a mixture.

Concentration Gradient There is a region of high concentration and a region of low concentration.

Go to page 7 in the note packet and learn about the use of square brackets. [ ]

Do the activity The Tea Cup & The Swimming Pool on page 8.

When the concentration of particles is the same throughout a mixture. Equilibrium When the concentration of particles is the same throughout a mixture.

Equilibrium There is no region of high, nor a region of low concentration of particles.

All particle continue to move. Equilibrium All particle continue to move.

Diffusion Concentration gradient Equilibrium

The Movement of Materials Across Membranes TRANSPORT The Movement of Materials Across Membranes

Materials move down the concentration gradient and across a membrane. Passive Transport Materials move down the concentration gradient and across a membrane.

What determines if a particle can go through a channel?

Dialysis Tubing

The passive transport of water across a membrane. Osmosis The passive transport of water across a membrane.

Thistle Tube Demo

thistle tube molasses water Selectively permeable membrane

Active Transport Particles move Across a SPM. Against the concentration gradient. The cells must spend energy.

(from an area of _____ concentration to an area of ___ concentration) Active transport allows particles to move against the concentration gradient. (from an area of _____ concentration to an area of ___ concentration) LOW HIGH

An example of Active Transport: All animal cells have a Sodium Potassium pump that pumps sodium (Na+) to the outside of cells and potassium (K+) to the inside of cells.

This ‘pump’ allows nerve cells to carry electrical messages through the body! + + + + + + + + + - - - - - - - - - - - - - - - - - Nerve cell

The Cell Membrane of a nerve cell

Endocytosis Particles move INTO the cell by folding a portion of the membrane around a particle, resulting in a vesicle.

Pinocytosis - drinking There are two types of Endocytosis: Phagocytosis - eating Food particles Pinocytosis - drinking Dissolved materials

Pinocytosis The solute particles are too small to see but too big to pass through the membrane.

Exocytosis Particles move OUT OF a cell by fusing vesicles with the cell membrane.

Maintaining water balance in Protists

Facilitated Transport (Facilitated Diffusion) -Diffusion using protein channels

Transport protein

Gated channel

The End