Cell Unit Notes Lecture II Cell Biology Standards in Lecture II > 1a ~ students know cells are...
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Transcript of Cell Unit Notes Lecture II Cell Biology Standards in Lecture II > 1a ~ students know cells are...
Cell Unit NotesCell Unit NotesLecture IILecture II
Cell Biology Standards in Lecture IICell Biology Standards in Lecture II
> 1a ~ students know cells are enclosed > 1a ~ students know cells are enclosed within semi permeable membranes that within semi permeable membranes that regulate their interactions with their regulate their interactions with their surroundingssurroundings
The Cell MembraneThe Cell MembraneThe The cell membrane regulates what regulates what entersenters
and and leavesleaves the cell the cell It also provides support and protectionIt also provides support and protectionThe cell takes in food and water and The cell takes in food and water and
eliminates wastes through the cell eliminates wastes through the cell membranemembrane
The cell membrane is The cell membrane is selectively selectively permeablepermeable
Selective PermeabilitySelective Permeability
The Lipid BilayerThe Lipid Bilayer Most cell membranes are made up of a double-Most cell membranes are made up of a double-
membrane layer called the membrane layer called the lipid bilayerlipid bilayer Along with lipids the membrane also has Along with lipids the membrane also has
proteins proteins that are “stuck” in it that are “stuck” in it (see below)(see below)
The Lipid BilayerThe Lipid Bilayer
Along with the proteins are Along with the proteins are “carbohydrate “carbohydrate chains”chains” that are attached to the protein that are attached to the protein
These “chains” act like an identification card or These “chains” act like an identification card or “face” so the cell can be recognized “face” so the cell can be recognized
Proteinchannel
Carbohydratechains
DiffusionDiffusion All All livingliving cells are surrounded cells are surrounded
by and full of liquidby and full of liquid Even a cactus in the desert Even a cactus in the desert
has moist cells in it’s living has moist cells in it’s living tissuetissue
One of the most important One of the most important functions of the cell functions of the cell membrane is to regulate the membrane is to regulate the movement of molecules movement of molecules from one side of the from one side of the membrane to the othermembrane to the other
DiffusionDiffusion The The concentration
of a solution is the of a solution is the relative “purity” of a relative “purity” of a liquidliquid
There can be a There can be a high concentration to a low concentration
A solution will A solution will movemove in the direction of in the direction of high concentration to low concentration and and this is called this is called Diffusion
DiffusionDiffusionDiffusion allows Diffusion allows
substances to cross substances to cross the cell membrane the cell membrane without requiring the cell to use energy
This is This is veryvery important since important since energy energy mustmust be be conserved – even at conserved – even at the cellular level!the cellular level!
OsmosisOsmosis Selective permeability
means that only means that only select select “things” can pass “things” can pass through the membranethrough the membrane
Osmosis is is “the “the diffusion of water across diffusion of water across a selectively permeable a selectively permeable membrane”membrane”
Osmotic PressureOsmotic Pressure Isotonic – means that on
both sides of the cell membrane it is the same “concentration”
Hypotonic – the cell fills up with water and is in danger of “bursting”
Hypertonic – the cell loses much of its water concentration and can “shrink”
(Animal Cells react differently than plant cells because of the cell wall that plant cells have)
Osmotic Osmotic PressurePressure
Facilitated DiffusionFacilitated Diffusion This is This is diffusion
across the cell membrane with the with the “help” of proteins“help” of proteins
It still flows from a It still flows from a high to high to low concentrationlow concentration
Facilitated Facilitated Active and Passive TransportActive and Passive Transport
Active TransportActive Transport Active transport requires
“action” or “action” or energy energy in order in order to move these particles to move these particles across the cell membraneacross the cell membrane
The input of energy along The input of energy along with special proteins on with special proteins on the surface of the cell can the surface of the cell can move any particles move any particles across any “gradient”
Gradient – relative – relative concentration of a solutionconcentration of a solution
Endocytosis & ExocytosisEndocytosis & Exocytosis
ExocytosisExocytosis The The removal of large of large
amounts of material amounts of material from the cell is known from the cell is known as as exocytosis
The The vesicle fuses with fuses with the cell membrane the cell membrane and forces its and forces its contents out of the contents out of the cellcell