The Human Body = HOMEOSTASIS (maintaining a constant condition)
The Plasma Membrane = The Cell Membrane The Most Important Job… Maintaining HOMEOSTASIS...
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Transcript of The Plasma Membrane = The Cell Membrane The Most Important Job… Maintaining HOMEOSTASIS...
Day 1-1 (4A) A lab technician needs to determine whether cells in a test tube are prokaryotic or eukaryotic. The technician has several dyes she could use to stain the cells. Four of the dyes are described in the table below:
Dye Test Acridine orange Stains DNA and RNA Osmium tetroxide Stains lipids Eosin Stains cell cytoplasm Nile blue Stains cell nuclei
Which dye could the technician use to determine whether the cells are prokaryotic or eukaryotic? F acridine orange G osmium tetroxide H eosin J Nile blue Day 1-2 (4B) Which of the following pairs matches a cell organelle with its function? F chloroplast—movement G nucleus—cell regulation H vacuole—energy production J mitochondrion—photosynthesis
The Most Important Job…
Maintaining HOMEOSTASIS
•Homeostasis = internal balance
•All living cells must maintain balance
How does it maintain homeostasis?
The plasma membrane controls what goes in and out
•Like a good bouncer
How does it maintain homeostasis?
c). allow waste and other products to leave the cell.
b). remove excess amounts of these nutrients when levels get so high that they are harmful.
a). allow a steady supply of water, glucose, amino acids, and lipids to come into the cell.
Selectively Permeable Membrane
Allows some substances to cross and not others
H2Osugar
lipids
salt
waste
• Small uncharged polar particles may pass
• Large uncharged polar molecules and ions
cannot pass
Selectively Permeable Membrane
Structure Of The Plasma Membrane
Phospholipid bilayer
•2 layers of lipids
•Phosphate head - Hydrophilic - Polar
•Fatty acid tail - Hydrophobic - Non polar
• To make the cell membrane, phospholipids come together to make two layers
• Which option makes the most sense? WHY?
A B C
Structure Of The Plasma Membrane
Membrane Proteins
•Transport channels
•Chemical receptors
•Cell to cell communication
Structure Of The Plasma Membrane
Cholesterol
•Keep the phospholipids spaced apart
•Keeps the membrane fluid/flexible
Structure Of The Plasma Membrane
Surface Carbohydrates
•Cell signaling
•Cell recognition
•Cell adhesion
Remember Smelly Balloons?
•Just like the balloon the cell membrane is selectively or semi permeable
•This means only some things can diffuse through the cell membrane
• Now lets talk more about diffusion…
Passive TransportPassive Transport -Requires -Requires NO EnergyNO Energy--Molecules move from an area of HIGH concentration to an area of LOW concentrationMolecules move from an area of HIGH concentration to an area of LOW concentration-With the concentration gradient-With the concentration gradient
-Diffusion-Diffusion-Facilitated Diffusion-Facilitated Diffusion-Osmosis-Osmosis
Important Vocabulary
Solute - The solid substance that is dissolved in a solvent.
Solvent - The liquid substance in which the solute is dissolved.
Solution - The mixture of two or more substances (solute and solvent) in which
the molecules of the substances are evenly distributed.
DiffusionDiffusionThe passive movement of molecules from an area of high concentration to an area of low concentration
Facilitated DiffusionDiffusion where a protein carrier molecule
or channel helps transport molecules across the membrane
OsmosisOsmosisThe diffusion of water across a selectively permeable membrane
•Water moves from an area of high water concentration to an area of low water concentration
•Water moves to where there are MORE solute molecules
Where are the solute ions more concentrated?
Which way will theWhich way will the Cl- Cl- andand Na+Na+ ions move?ions move?
1)1) Hypertonic solutionHypertonic solution2)2) Hypotonic solution Hypotonic solution 3)3) Isotonic solution Isotonic solution
OsmosisOsmosis occurs in 3 types of solutions.
Hypertonic EnvironmentHypertonic Environment
• An environment with a more solute concentration compared to another
97% NaCl3% H2O
3% NaCl97% H2O
OsmosisOsmosis = The diffusion of water across a membrane.
Water moves
OUT
Hypotonic EnvironmentHypotonic Environment
• An environment with a less solute concentration compared to another
3% NaCl97% H2O
97% NaCl3% H2O
OsmosisOsmosis = The diffusion of water across a membrane.
Water moves
IN
Isotonic EnvironmentIsotonic Environment
• An environment with equal solute concentration compared to another
3% NaCl97% H2O
3% NaCl97% H2O
OsmosisOsmosis = The diffusion of water across a membrane.
Water moves
IN & OUT
Which way will the water diffuse?What type of solution is in each beaker? IsotonicIsotonicHypertonicHypertonic HypotonicHypotonic
Active TransportActive Transport -Requires -Requires EnergyEnergy--Molecules move from an area of LOW concentration to an area of HIGH concentrationMolecules move from an area of LOW concentration to an area of HIGH concentration-Against the concentration gradient-Against the concentration gradient
-Endocytosis-Endocytosis-Exocytosis-Exocytosis-Protein Pump-Protein Pump
Exocytosis and Endocytosis are ways a cell can pass proteins out of or into the cell.
Exocytosis-a membrane bound vesicle, fuses with the membrane, and releases its contents outside the cell
Endoocytosis-the cell membrane engulfs (“eats”) molecules, and takes them into the cell