Transcript Chapter 3 Exchanging Materials with the Environment

Chapter 7.3
Exchanging Materials
with the Environment
http://learn.genetics.utah.edu/content/begin/cells/scale/
http://www.youtube.com/watch?v=
Qqsf_UJcfBc
I. General Function
A. The structure of a cell (plasma) membrane
determines its function.
B. Nutrients must go in: Water, Sugar,
Amino acids, oxygen, CO2 in autotrophs,
and Ions (such as Na+, K+, Mg+2, Ca+2, H+)
C. Wastes must go out: CO2 , nitrogengous
wastes (from the digestions of proteins)
I. General
Structure
A.
Cell membrane = Layer of phospholipids,
proteins, and cholesterol.
1. Fluid Mosaic Model: phospholipids, lipid
rafts, proteins are in constant motion.
2. Membrane is selectively permeable =
semipermeable.
I. General Structure
3. Phospholipids
a. Have hydrophilic heads that point
outward and hydrophobic tails that point
inwards
b. Molecules that go through phospholipids:
i. small, hydrophobic (O2, CO2, N2)
ii. small polar (glycerol)
4.Protein channels are embedded.
a. Some go all the way through to transport
food and wastes.
i. Large uncharged or polar molecules
(amino acids, glucose, nucleotides)
ii. Ions (Na+, K+, Mg +2, Ca+2, H+)
b. Some are on outside or inside only for
signaling, anchoring, receiving, cell
identification, cells adhering to other cells,
attachment to cytoskeleton.
i. Glycolipids and
glycoproteins attached
to some outside
proteins receive
chemical messages
from other cells.
5. Water has its
own channels
(aquaporins)
http://www.youtube.com/wat
ch?v=1Uw6u0fzNsE
http://www.youtube.com/watch?v=
ERTkE91ICB8&feature=related
6. Cholesterol helps
the membrane
be flexible.
III. Passive Transport
A. Diffusion
1. The NET movement of particles from an
area of high concentration to an area of
low concentration. (That is, the movement
of particles along the concentration
gradient).
Diffusion cont’
a. Does not require a membrane (think
food coloring in water).
b. Can occur in solids, liquids, and gasses.
Diffusion cont’
c. Particles are in random motion, bumping
each other and spreading out. (This causes
entropy to increase = The 2nd Law of
Thermodynamics: Particles move from a
state of order to a state of disorder).
d. Particles reach
equilibrium, but
equal numbers
are still going
both ways.
Diffusion cont’
e. Rate depends on concentration, temperature,
and mass of particles.
B. Osmosis
1.The diffusion of water across a
semipermeable membrane.
http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&ResourceID=418
2. Tonicity: The concentration of the solution
COMPARED TO the cell.
Tonicity
a. Isotonic Solution: Same concentration outside
the cell as inside. Result: The cell stays normal.
i. E.g., 5% dextrose in human.
ii. Kidneys and skin help maintain balance.
Tonicity
b.
Hypertonic Solution: The solution has more
particles compared to the cell = the cell has
more water than the solution…SO… water
moves out of the cell and the cell shrivels up.
What happens when
you put salt on a
slug?
http://www.youtube.com/watch?v=
Tonicity
c. Hypotonic Solution: Solutions have fewer
particles compared to the cell = solution has
more water than the cell…SO…water moves
into the cell and the cell swells.
i. Animal cells blow up
• Freshwater protists have contractile vacuoles.
Tonicity
ii. Plant cells become turgid (very full of water).
C. Facilitated Diffusion
1. When proteins are too big or too charged
to pass through membrane.
a. Just like diffusion, particles move
with the concentration gradient;
requires no energy.
b. Uses a protein channel that is
Sugar
Insulin Transport specific. E.g., glucose channels.
protein
http://www.youtube.com/watch?v=
s0p1ztrbXPY&NR=1
IV. Active Transport
A. When cells needs to
keep particles in or out
of cell in high
concentration
1. Takes energy (ATP) to
move them against the
way they want to
go…to move them
against the
concentration gradient.
a. 1/3 of all your energy goes to the Na+ / K+
pump of the nerves. Also important in
muscles and absorption of food from gut.
b.Root cells take up nutrients from the soil by
active transport…water is pulled in after
them.
Active Transport Animation
Cell Membrane Video
http://www.youtube.com/watch?v=
vh5dhjXzbXc&playnext=1&list=P
L441A7875C14F139D&index=20
V. Co-Transport
A.
The movement of one particle drives the
movement of another.
1. Example:
VI. Bulk Transport
A.
B.
Endocytosis = food taken into a cell
1. Pinocytosis = “drinking” of particles
2. Phagocytosis = “eating” of particles
Exocytosis = particles (wastes and
products) taken out of a cell.
http://www.youtube.com/
watch?v=4gLtk8Yc1Zc&
NR=1
VII. Review of Transport
•
http://www.northland.cc.mn.us/biology/Biology1111/animations/active1.swf
CELL TYPES REVIEW
• http://www.wiley.com/legacy/college/boyer
/0470003790/animations/cell_structure/cell
_structure.htm
VIII. When Transport
Doesn’t Happen
• Potential energy
is stored, like
water behind
a dam)
(imp in ATP production)
• Electrical
potential
can build up
(imp in nerves)
IX. Cystic Fibrosis