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further into the cell membrane
Cell Transport
Cell MembraneWhat makes up the cell membrane?
A) Phospholipid bilayera) Hydrophilic head (water-loving) towards the outside
1) Phosphate group b) Hydrophobic tail (water-fearing) towards the inside
1) Fatty acid chain B) Cholesterol
a) Keeps the cell fluid, prevents it from freezing or meltingC) Carbohydrates
a) Help stabilize the membrane structureD) Proteins
a) Variety of functions 1) Transport proteins 2) Enzymes
E) Fluid Mosaic Model
-Many proteins and carbohydrates are also found among the lipid bilayer(Proteins embedded in lipid bilayer, Carbohydrates attached to
proteins) - So many different molecules in membrane, we call it a “mosaic” of different molecules -Mosaic- kind of art that involves bits and pieces of different materials and colors.
Mosaic model?
Plasma/ Cell
MembraneThe membrane is fluid, and the molecules are always moving. It has about the same consistency as olive
oil.
Cell membrane is…
Selectively permeable, what does that mean?
>>Some substances can pass across them and others cannot
Cell membranePhospholipids bilayer
Made of a negatively charged phosphate “head”PO4
3-
Attracts water because the phosphate is charged (-)
Water is a polar , slightly positive ends and slightly
negative ends
Attached to the phosphate group are 2 fatty acid chainsHydrophobic= don’t like waterSo the inside of the cell membrane
doesn’t let water in but the outside allows cells to be dissolved in aqueous environments
Passive Transport
•The movement of materials across the cell membrane without using cellular energy
Active Transport• The movement of materials against a concentration difference
Passive Transport:Diffusiono In any solution, solute particles
are constantly moving, colliding, and randomly spreading apart.
o The particles (solute) move from an area of more concentration to an area of less concentration.
Passive Transport: Facilitated Diffusion
o Uncharged ions easily pass through the lipid bilayer through diffusiono What about larger molecules with a charge?
o Process in which molecules that cannot directly diffuse across the membrane pass through special protein channels
o Proteins act as carriers or channelso Red Blood cells and glucose
Passive Transport:Osmosis o Osmosis is a type of facilitated
diffusion. o Osmosis is the diffusion of water through a selectively permeable membrane. o Water moves instead of the solutes from higher concentration to lower concentration.
Hypertonic: Solution has a higher solute concentration than the cellHypotonic: Solution has a lower solute concentration than the cell Isotonic: The concentration of solutes is the same inside and outside the cell.
Reminder: In osmosis the water is moving, not the solutes
Passive Transport Review
NO ENERGY REQUIRED!
Active Transport Movement of materials against a concentration difference
Requires Energy
Carried out by proteins or protein pumps
Active Transport:Molecular Transport
Protein pumps: - Energy from ATP is used to pump small molecules and ions across the cell membrane. -Change shape during the process- sodium-potassium pump
Carrier proteins: -Specific - not an open pathway like the protein pumps
-Both use energy in the form of ATP- Both go from low concentration to high concentration
Active Transport: Bulk Transport
Endocytosis- Taking into the cell infolding or pockets off the cell membrane Phagocytosis- extensions of cytoplasm surround the particle and package it within a food vacuole. Pinocytosis- brings water into the cell from the exterior Exocytosis-Taking out of the cell
What is the below an example of?
The effect on Osmosis on cells: Egg Lab
