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
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