Download Cell Transport

Movement Through the
Membrane
Section 7-3
Properties of Water
What makes water so special?
Cohesion & Adhesion
 Cohesion


H bonding between H2O molecules
water is “sticky”
 surface tension
 drinking straw
 Adhesion

Try that
with flour…
or sugar…
H bonding between H2O & other substances
 capillary action
 meniscus
(water climbs up)
Water is the solvent of life
 Polarity makes H2O a good solvent

solvents dissolve solutes creating solutions
(water)
(sugar or salts)
(lemonade)
What dissolves in water?
 Hydrophilic
substances have attraction to H2O
 polar or non-polar?

What doesn’t dissolve in water?
 Hydrophobic
substances that don’t have
Oh, look
an attraction to H2O
hydrocarbons!
 polar or non-polar?

fat (triglycerol)
TED-Ed Video
• Properties of Water
Cell Membrane
• SEMI-PERMEABLE
• Structures:
a. Phospholipid bilayer – hydrophobic
(scared of water)
b. Proteins – gatekeeper for substances
c. Carbohydrates – identifies the cell
Figure 7-12 The Structure of the
Cell Membrane
Section 7-3
Cell Membrane
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
Cell Transport Types:
Passive Movement: No
energy required
Active Movement: Energy
required by cell
Diffusion
• Is passive!
• Movement of a
substance from high
to low concentration
• Ex: O2 and CO2
moving in/out of body
animation
Facilitated Diffusion
• Is Passive!
• Movement of substance from high to low concentration
across a membrane through a protein channel.
• Ex: large molecules (glucose) or ions
Animation
Osmosis
• Movement of water from high to low
concentration across a semi-permeable
membrane.
Animation
• Descriptions for solutions on either side of
a membrane:
1. Hypertonic –solute is in high
concentration so water is low.
2. Hypotonic – solute is in low
concentration so water is high.
3. Isotonic – solute concentration is
equal on both sides.
How do cells deal with osmotic
pressure?
1. Tough cell walls can
protect from bursting.
2. Contractile vacuoles pump
out excess water.
Many cells cannot cope with
osmotic pressure:
*dangerous to drink sea water it will speed up
dehydration (and death) by drinking sea water.
*water injected into you will burst RBC’s
Active Transport
• Requires energy for the cell to complete.
• Movement of molecules from LOW to HIGH
• Examples: Ion movements into or out of
cell.
Animation
Bulk Transport: requires energy!
• Endocytosis – cell engulfs larger molecules
• Exocytosis – release of wastes or cell
products outside of cell
Endo/Exo Animation
Cell Diversity
Section 7-4
Diversity of Cellular Life
Two types of living cellular organisms:
• Unicellular Organisms
• Multi-cellular Organisms
In multi-cellular organisms, there is:
1. Cell Specialization – cells perform
certain functions based on DNA segment
that is activated.
2. Levels of Organization – cells,
tissues, organs, systems, organism
Levels of Organization
Levels of Organization
Section 7-4
Muscle cell
Smooth muscle tissue
Stomach
Digestive system
Bill Nye: Cells
http://www.free-tv-videoonline.me/player/gorillavid.php?id=3hp3jtluz6vr