Title: Cell and organelle membranes are made of two layers - lipid bilayers.
1Cell Membranes
- Cell and organelle membranes are made of two
layers - lipid bilayers.
2- Cell membranes are semipermeable
- It acts like a screen by letting some chemicals
in stopping others. - It is like the doors of the cell.
3Passive Transport
- The random movement of particles from a greater
to a lesser concentration. - Uses no energy.
- Three types
- Diffusion
- Osmosis
- Facilitated diffusion
4Diffusion
- The random movement of particles from a greater
to a lesser concentration.. - Uses no energy.
- A molecule will slide through the membrane only
if it will fit.
5Simple Diffusion.
- Things just naturally want to spread out.
- That is what these red particle are doing. They
Are DIFFUSING.
6- The red particle and the blue particles are
diffusing in this picture. - They have to cross a permeable membrane to do it.
7- Osmosis
- Osmosis is the diffusion of water.
8- In this case, the membrane is SEMI-permeable.
- Only the small particles (the water) can get
through. - When only water diffuses, it is called OSMOSIS.
9Facilitated Diffusion
- The molecules that are too big to get through the
membrane use proteins. - Requires no energy!
- There are different types of proteins carrier
and channel
10 A big molecule can use a CHANNEL PROTEIN to get
through.
11- CARRIER PROTEIN are shaped just like specific
molecules. - They grab molecules, suck them in, and spit
them out on the other side of the membrane. - This uses no energy.
Glucose molecules
12To review
- Simple Diffusion, Osmosis, and Facilitated
Diffusion - Use no energy (Passive Transport)
- Move particles from greater to a lesser
concentration - But what if you want to concentrate a chemical
on one side of a membrane?
13Active Transport
- A process that requires energy
- Proteins move molecules across the membrane from
lesser to greater concentration. - Except for the above two points, it is the same
as facilitated diffusion. - 2 Types
- Molecular transport
- Bulk transport
- Endocytosis
- Exocytosis
14ACTIVE TRANSPORT!
Active Transport is ACTIVE. It uses energy.
Ex. Sodium Pump and minerals entering root cells
15- Molecular Transport
- occurs when small molecules are carried across
the membranes by pumps made of proteins.
16This is an example of Molecular Transport
17Bulk Transport
- Movement of large molecule or clumps of material
by movement of the cell membrane. - Two main types
- Endocytosis
- exocytisis
18Endocytosis
- process of taking material into the cell by
infoldings or pockets of the cell membrane
19A specific type of endocytosis is phagocytosis
(cell eating)
- During phagocytosis, extensions of cytoplasm
surround the particle and package it to a food
vacuole. The cell engulfs it!
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21Exocytosis
- Larger molecules are released by the cell in a
process called exocytosis. - the membrane of the vacuole surrounding the
material fuses with the cell membrane forcing
out its contents.
22Other terms to know about osmosis
- Isotonic Hypertonic Hypotonic
23Isotonic Concentration of solutes(molecules) is
the same inside and out of the cell. Water moves
equally in and out of cell.
24Hypertonic Solution has higher solute
concentration than the cell. Water moves out of
cell.
25Hypotonic Solution has lower solute
concentration than the cell. Water moves into
cell.