Download The Cell Diffusion-Osmosis

Cell Diffusion
and Osmosis
Regular Biology
Mr. Wilbrandt
Targets for Today
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I will be able to…..
Identify how things go in and out of
cells.
Understand how cells maintain
homeostasis.
recognize how membranes protect
the cell.
Functions of Membranes
1. Protect cell
2. Control incoming and outgoing
substances
3. Maintain ion concentrations of
various substances
4. Selectively permeable - allows some
molecules in, others are kept out
Phospholipid Bilayer
Fluid Mosaic Model
Blood-Brain Barrier
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Allows some substances into the
brain, but screens out toxins and
bacteria
Substances allowed to cross
include:
water, CO2, Glucose, O2, Amino
Acids, Alcohol, and
antihistamines. HIV and bacterial
meningitis can cross the barrier.
Solutions
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Solutions are made of solute and a
solvent
Solvent - the liquid into which the
solute is poured and dissolved. We
will use water as our solvent
today.
Solute - substance that is
dissolved or put into the solvent.
Salt and sucrose are solutes.
Methods of Transport Across
Membranes
1. Diffusion
2. Osmosis
3. Facilitated Diffusion
4. Active Transport
Methods of Transport Across
Membranes
1. Diffusion -passive transport –
no energy expended
2. Osmosis - Passive transport of water
across membrane
3. Facilitated Diffusion - Use of proteins
to carry polar molecules or ions across
4. Active Transport- requires energy to
transport molecules against a
concentration gradient –
energy is in the form of … ATP
Diffusion
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Movement of molecules from an
area of high concentration to an
area of low concentration.
Movement from one side of a
membrane to another, unfacilitated
Diffusion
Osmosis
Tonicity is a relative term
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Hypotonic Solution - One solution
has a lower concentration of
solute than another.
Hypertonic Solution - one solution
has a higher concentration of
solute than another.
Isotonic Solution - both solutions
have same concentrations of
solute.
Plant and Animal Cells put into
various solutions
Types of Transport
Today’s Lab
 We
are using baggie as
the cell membrane - It is
selectively permeable
 The solute is either the
starch solution or the
Iodine solution
 What is the solvent?
Test for Starch
Elmhurst College Website
Review: 4 Methods of
Transport Across Membranes
1. Diffusion
2. Osmosis
3. Facilitated Diffusion
4. Active Transport