Cell Membrane Cell Membrane is very complex. It’s made of phospholipid bilayer with proteins throughout.

1.some proteins extend all the way through (Integral Proteins) and some stay on surface (Peripheral Proteins) 2.integral proteins form channels or carriers 3.peripheral act as recognition sites

Phospholipid Bilayer Hydrophilic= water loving (phophate head) Hydrophobic= water fearing (lipid tails)

Fluid Mosaic Model lipids and proteins of cell membrane are always in motion, drifting around, hence name Fluid Mosaic Model of membrane structure

Fluid Mosaic Model Cell membrane acts as a dam or pump for water-soluble molecules that can’t pass freely through.Interactive Educational AnimationsInteractive Educational Animations Water diffuses across the membrane, called osmosis. This regulation of water across the cell membrane is vital to homeostasis.

DIFFUSION All particles are moving and therefore have energy of motion called kinetic energy, whether living or nonliving. When there is a difference in concentration across a space this is called a concentration gradient.

DIFFUSION The movement from higher concentration to lower concentration. This happens b/c of kinetic energy. Diffusion

Rate of diffusion 1.Concentration- more concentrated diffuses faster. 2.Pressure- increasing pressure will increase kinetic energy and diffusion. 3.Temperature- higher temps increase kinetic energy and also diffusion.

Dynamic Equilibrium Once diffusion has occurred and there are equal concentrations, there is still continuous movement (kinetic energy), however there is no more concentration change

Osmosis Diffusion with water across a semipermeable membrane. Very vital to biology. Osmosis animation

HYPERTONIC SOLUTION The concentration of solute molecules outside the cell is higher than conc. inside the cell. H 2 O diffuses out of the cell to equilibrium. -Cell in hypertonic solution shrink. Plant cells detach from cell wall (PLASMOLYSIS), plants wilt.

HYPOTONIC SOLUTION The conc. of solute molecules outside the cell is lower than conc. inside the cell cytosol. H 2 O diffuses into the cell to equilibrium. -Cell in hypotonic solution swell. Animal cells in this environ. will burst (CYTOLYSIS). Plant cells have cell wall and just become rigid.

ISOTONIC SOLUTION conc. of solutes is equal in and out of cell. Cells must be able to attempt to adapt to these environments. Must actively transport water and materials into and out of cell.

Passive Transport- no energy required. 1. Diffusion, Osmosis- most molecules can not enter or exit cell this way. (oxygen, H 2 O)

Passive Transport 2. Facilitated Diffusion- no energy required. Molecules are diffused into and out of cell with the help of molecule-specific carrier proteins and ion channels (protein tunnel). (Glucose, Na+, K+)

Active Transport- requires energy (ATP)- usually against the conc. gradient- uses carrier proteins. 1. Sodium-Potassium Pumps- animal cells, pump Na+ out and K+ in.

Active Transport 2. Plant roots- nutrients inside roots more conc. than out. Pumped in.

Active Transport 3. Bulk Transport- large molecules, food packaged in membrane-bound sacs (vesicles) to move across membrane. a. Endocytosis- cell membrane folds in, surrounds molecule, becomes sac

Active Transport b. Pinocytosis- “cell drinking” brings liquid in c. Phagocytosis- “cell eating” brings food in; lysosomes digest; White Blood Cells

Active Transport d. Exocytosis- vesicles made by golgi or ER and merge w/ cell membrane to exit material from cell.

Organization of Multicellular Organisms 1.Cell- smallest unit of life capable of all functions of life 2.Tissue- group of cells, perform a specific function

Organization of Multicellular Organisms 3. Organ- several different types of tissue function together for a specific purpose

Organization of Multicellular Organisms 4. Organ System- several organs working together to perform a function

Organization of Multicellular Organisms 5. Organism- all organ systems working together