Homeostasis and Transport Unit 2 Sec 7.3 Homeostasis and Transport

I. Cell Wall A. Structure Composed of cellulose (__________) Cellulose is a polysaccharide composed of smaller units called _______________ (glucose) Glucose protects and supports cell

II. Cell Membrane Cell Membrane: Boundary of every cell Controls what enter and leave cell through selective permeability Boundary of every cell

II. Cell Membrane A. Membrane Lipids Phospholipid bilayer: Steriods: Polar hydrophilic head Nonpolar hydrophobic tail Steriods: Cholesterol provides strength and stability in movement

Cell Membrane

II. Cell Membrane B. Membrane Proteins Integral proteins: embedded in lipid bilayer & extend from interior  exterior of CM

C. Fluid Mosaic Model Phospholipid bilayer acts more like a fluid than a solid

III. Passive Transport Passive Transport: the movement of substances across the cell membrane without the use of energy

III. Passive Transport How molecules move: 1. random fashion bouncing off other things 2. constantly in motion From high to low concentrated area Continue until equilibrium

III. Passive Transport Factors Affecting the Movement Temperature: hot= cold= Size of pores and particle size Mass

Types of Passive Transport Diffusion Osmosis Facilitated Diffusion

A. Diffusion Diffusion: movement of molecules from an area of _______ concentration to an area of ________________ __________________________ Cool Science Trick Concentration Gradient:

A. Diffusion Equilibrium: concentration of substances in an area is _______ Results with: Diffusion Across Membranes:

B. Osmosis Osmosis: diffusion of ________ molecules across cell memb. from area of _______ con. to an area of ________ con. Moves:

Who gets it? What is diffusion? What is equilibrium? What is osmosis?

B. Osmosis Direction of Osmosis: Hypotonic: Concentration of solute is lower outside the cell Hypertonic: Concentration of solute is higher outside the cell Isotonic: solutes in and outside the cell are equal

B. Osmosis How Cells Deal w/ Osmosis: Certain unicellular organisms must maintain a low level of water Use_______________ to get rid of extra water Contractile Vacuole:

B. Osmosis How cells deal w/ Osmosis: Plant root cells: need a __________ environment Turgor Pressure: Cytolysis Hypertonic Environment.: Plasmolysis:

C. Facilitated Diffusion Facilitated Diffusion: substances require a ____________ for transport b/c it cannot diffuse through membrane Molecules that use this transport: Too big Not charged monomers

D. Diffusion through ion channels Ion Channel: pathway for specific ion to pass through cell membrane Stimuli will control gates to channels: __________________

IV. Active Transport (AT) 1) AT: movement of materials from a area of ______ concentration to a _______ concentration using energy 2) Molecule is ___________ or not compatible with cell

IV. Active Transport 3) Bulk Transport: Used to transport macromolecules or a large quantity of substance A) Endocytosis: a cell will engulf external substances into cell

IV. Active Transport A. Endocytosis (continued) -2 Types 1) Pinocytosis: cell ___________ 2) Phagocytosis: cell __________

Endocytosis and Exocytosis

IV. Active Transport B) Exocytosis: process to remove materials from cell a) vesicle w/in the cell is sent to cell membrane b) vesicle fuses w/ the cell membrane & releases substance

IV. Active Transport C. Pumps: Proteins are embedded in the cell membrane Molecules fit into the protein and are moved across from a _________ to _________ concentration