Transport-cell membrane Do Now: What is homeostasis? What is transport? Brainstorm: Can you brainstorm one way that transport helps to maintain homeostasis in your body? (explain)

Definitions….. TRANSPORT -absorption, distribution, circulation, cyclosis, osmosis, diffusion HOMEOSTASIS -maintaining a stable internal environment

What does venom have to do with cell membranes? Brown Recluse Spider Bite!

Western Diamondback Rattlesnake bite!

Why is the cell membrane so important???

Selectively permeable membrane Semi permeable membrane Names! Cell membrane Plasma membrane Selectively permeable membrane Semi permeable membrane

Honors Know diagram on pg 82! Variety of Proteins: I. Glycoproteins Receptor protein Recognition proteins Enzymatic proteins Attachment proteins Transport proteins

Functions of the Cell Membrane Protects the cell Regulates what goes in and out of cell Helps to communicate with other cells Creates attachments between cells Dynamic!

Fluid Mosaic Model dev. By Singer & Nicolson 1972 Proteins move within layers of lipids w/I viscous fluid Hydrogen bonds can form between water and phospholipid heads inside and outside of cell The more double bonds there are in the tails the more fluid the membrane Incr. in temp. causes membr. To be more fluid (because mol. Move faster) Decr. Temp. (mol. Move slower -> less fluid)

Active & Passive Transport Illustrations Chapter 5 Lab Biology Chapter 5 Honors Biology

Movement from a high concentration to a low concentration! Passive Transport Requires NO energy!! Movement from a high concentration to a low concentration!

Passive Transport 1. diffusion 2. osmosis 3. facilitated diffusion 4. diffusion through ion channels

Diffusion

Diffusion Molecules moving from a greater concentration to a lower concentration Ex: perfume

Vocabulary Concentration gradient: difference in concentrations Equilibrium: particles/molecules are equal on both sides of membrane

More diffusion -> “equilibrium”!!

Osmosis

Osmosis Movement of WATER from a high concentration to a low concentration across the cell membrane

Iso – Hyper – Hypotonic Solutions

Vocabulary Isotonic: concentration inside and outside of cell are the same  no diffusion Hypertonic: when concentration of solute outside of cell is greater, water moves out of cell (shrink) Hypotonic: concentration of solute inside of cell is greater, water moves into cell (burst)

Plasmolysis

Plants! Plasmolysis = cell shrinks away from cell wall due to water loss ex: drought (low rain fall) causing plants to wilt Turgor Pressure = cell wall sustains shape, otherwise would explode

Facilitated Diffusion

Facilitated Diffusion Carrier Protein – helps mol. Across membrane that are hydrophobic or too large -protein recognizes substance->changes shape->delivers substance to inside of the cell

Ion Channels

Ion channels -allows ions Ca2+ and Cl- to enter cell Some are open all the time Others are gated and will open when Cell membrane stretches Electrical signals Chemical signals

Movement from a LOW concentration to a HIGH concentation! Active Transport REQUIRES ENERGY! Movement from a LOW concentration to a HIGH concentation!

Active Transport 1. Sodium Potassium Pump 2. Endocytosis 3. Exocytosis

Active Transport

Sodium Potassium Pump -pumps like to keep ions in balance 3 Na+ out for every 2 K+ in This creates a build up of Na+ outside cell and K+ inside cell forming a net electrical charge across the membrane Allows for nerve impulses Contraction of muscles 1/3 of all energy in animal cells goes to running this pump even as we sleep!

Endocytosis

Endocytosis Take in external fluid, macromolecules and other large particles. Forms “vesicle” some fuse with lysosomes (digestion) others fuse with membrane of other organelles. 2 Types: a) pinocytosis – cell drinking fluid b) phagocytosis – cell eats

Exocytosis opposite of endocytosis!!