Unit 3 Sec 7.3

Homeostasis and Transport

I. Cell Wall

A. StructureComposed of cellulose (__________)

Cellulose is a polysaccharide composed of smaller units called _______________ (glucose)

Glucose protects and supports cell

II. Cell Membrane

Cell Membrane:Controls what enter and leave cell through

selective permeability

Boundary of every cell

II. Cell Membrane

A. Membrane LipidsPhospholipid bilayer:

Polar hydrophilic headNonpolar hydrophobic tail

Steriods:Cholesterol provides strength and stability in

movement

Cell Membrane

II. Cell Membrane

B. Membrane ProteinsIntegral 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 things2. constantly in motion

From high to low concentrated areaContinue until equilibrium

III. Passive Transport

Factors Affecting the MovementTemperature: hot= cold=Size of pores and particle sizeMass

Types of Passive Transport

DiffusionOsmosisFacilitated 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?

1) What is diffusion?

2) What is equilibrium?

3) What is osmosis?

B. Osmosis

Direction of Osmosis: Hypotonic: Concentration of solute is lower

outside the cellHypertonic: Concentration of solute is higher

outside the cellIsotonic: solutes in and outside the cell are

equal

B. Osmosis

How Cells Deal w/ Osmosis:Certain unicellular organisms must maintain a

low level of waterUse_______________ to get rid of extra waterContractile Vacuole:

B. Osmosis

How cells deal w/ Osmosis:Plant root cells: need a __________

environmentTurgor Pressure:Cytolysis

Hypertonic Environment.: Plasmolysis:

C. Facilitated Diffusion

Facilitated Diffusion: substances require a ____________ for transport b/c it cannot diffuse through membraneMolecules that use this transport:

Too bigNot chargedmonomers

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 membraneMolecules fit into the protein and are moved

across from a _________ to _________ concentration