homeostasis requires exchanging materials with the environment. how do you do it?
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Homeostasis requires exchanging materials with the environment. How do you do it?. Surfaces of contact with the environment let in oxygen and nutrients and excrete wastes. The surface of contact between a cell and its environment is its plasma membrane. - PowerPoint PPT PresentationTRANSCRIPT
Homeostasis requires exchanging materials with
the environment.How do you do it?
Surfaces of contact with the environment let in oxygen and nutrients and excrete wastes.
The surface of contact between a cell and its environment is its plasma membrane.
Inside cell
Outside cell
Fluid Mosaic Model(description of membrane)
Cell/Plasma MembraneFluid Mosaic Model
• The cell, or plasma membrane is made of hydrophobic molecules called phospholipids.
• Proteins located in the membrane can flow/move and perform many functions, including receiving stimuli from the environment and transporting substances in and out of cell.
↓
The plasma membrane is semi-permeable / selectively permeable:
it controls what goes in/out of cell
Cell Membrane Diagram(add details as you go)
Phospholipid bilayer
Outside cell
Inside cell
Phospholipid Bilayer
Hydrophilic Phosphate Heads
HydrophobicTails
Inside of Cell
Outside of Cell
Saturated or Unsaturated?
Cell Transport movement of substances in and out of cell,
needed to maintain homeostasis
What substances does a cell need to move in and out?
Media Links For Lecture\08-02-MembraneStructure.mov
Water moves freely through aquaporins.O2 and CO2 move freely through membrane.
Polar particles need specialized carrier proteins:ions, glucose
Passive Transport
Does not require the use of energy from ATP.(uses the kinetic energy in matter/stuff moving in/out)
Diffusion – Spreading of matter from one area to another. Matter always diffuses from areas of higher concentration to areas of lower concentration EQUILIBRIUM (same concentration everywhere)
Diffusion is “free” because stuff moves down/with a concentration gradient.
Ex.: food coloring spreading/mixing in water;
H2O, O2, CO2, monomer nutrients (some) moving in/out of cell
Movie TimeCell Membrane & Passive Transport
Mrs. Nordstrom:*press esc key (leave presentation mode),
then double click below*
08-02-MembraneStructure.mov
08-10-Diffusion.mov
Osmosis – Diffusion of water through a semi-permeable membrane.
Water flows from areas of lower solute concentration (+ water) to areas of higher solute concentration (- water).
Osmosis - Solution Concentration & Effect on Cells(show cells in a solution & net movement of water) Hypertonic Isotonic Hypotonic Very Hypotonic
Hypertonic Solution(Hypotonic Cell)
Is there a concentration gradient?
H 2O
PlasmolysisCell shrinks
(loses water)
Isotonic Solution(Isotonic Cell)
Is there a concentration gradient?
EquilibriumHappy cell
Hypotonic Solution(Hypertonic Cell)
Is there a concentration gradient?
Cell swells(gains water)
H2O
Very Hypotonic Solution
CytolysisCell lysis
Cell swells(gains water)
H2OH
2O H2O
08-11-Osmosis.mov
• Movie Time *
Osmosis ORThe Movement of Water Through a Semi-Permeable Membrane
Mrs. Nordstrom:*press esc key (leave presentation mode),
then double click below*
Glucose always use F.D.
Ions use F.D.
Facilitated Diffusion – requires the use of a carrier protein on the cell membrane (still no ATP energy needed).Ex.: glucose molecules, ions – why? Polarity…Protein channels are specific for the particles they move.
Carrier Protein / Ion Channel
Movie Time
Facilitated Diffusion IllustrationAt Colorado State Univ. Web Page
Turgid or Flaccid??
Salt Water
Hypoto
nic
Hypertonic
(Macroscopic Term)
Turgid or Flaccid??
Tap Water
HypotonicHyp
erton
ic
(Macroscopic Term)
A B C
Hypertonic -
Hypotonic -
Isotonic –
Prefix refers to the amount of Dissolved Solute (stuff)
Excess ‘stuff’........
Less ‘stuff’……….
Equal ‘stuff’…………
Osmosis Practice
Can you predict what will happen?
Think of water and solute concentrations.
Cell is 95% Water
Cell’s Environment is
90% waterWater Pushes Out
Osmosis
Cell is 95% Water
Cell’s Environment is
100% water
Water Pushes into Cell
Osmosis
Cell is 95% Water
Cell’s Environment is
95% water
EQUILIBRIUM
Osmosis
Cell is 95% Water
Cell’s Environment
is 90% water
The Cell is ___________The Cell’s environment is____________
HypotonicHypertonic
The Future Fate of the Cell might be toPLASMOLYZE
Osmosis
Cell is 95% Water
Cell’s Environment is 100% water
The Cell’s environment is____________The Cell is ___________
HypotonicHypertonic
The Fate of the Cell is Cytolysis
OsmosisCell is 95% Water
Cell’s Environment is 95% water
The Cell’s environment is____________The Cell is ________________________ISOTONIC
The Cell is at Equilibrium
Cyclosis
Plasmolysis
Which is more Plasmolyzed?Which might be further in the
process of re-hydrating?
Normal Plant Cell Isotonic Cell
Isotonic Environment
Hypotonic Cell
Hypertonic Env.
Hypertonic Cell
Hypotonic Env.
Plasmolysis Cytolysis
RBC in Isotonic Environment
The cell is also Isotonic
PlasmolysisCytolysis
Cell is Hypotonic, Env. is Hypertonic
Cell is Hypertonic, Env. Is Hypotonic
A B C
Simple Diffusion
Movement of ‘stuff’ down the Concentration Gradient through a semi-permeable cell membrane by Kinetic Energy
Media Links For Lecture\08-10-Diffusion.mov
Passive Transport1. Osmosis
2. Diffusion
3. Facilitated Diffusion - Glucose
4. Ion Channels
Movement of water in / out of cell
Movement of H2O, O2, CO2, Urea, monomer nutrients: either in / out of cell
Movement of Glucose (C6H12O6) into the cell. Helped by a specific Integrated Protein
Movement of ions in / out of cell, must go through specific integrated proteins