Membranes organize a cell

1
Membranes organize a cells activities

• Concept 6.2

2
Membrane Structure

• Composition
• phospholipids
• Hydrophobic?
• Hydrophilic?

3
The cell membrane is made up of proteins and
lipids.

• It is called a phospholipid bilayer

4
Protein molecules are embedded in the bi-layer

• There can be several different proteins embedded
  in the bi-layer, some of the most common
  functions are
• Enzymes important chemical reactions
• Allow cells to communicate and recognize each
  other
• Help move substances across the membrane

5
Membranes regulate the traffic of molecules

• Concept 6.3

6
Diffusion

• the movement of molecules from an area of high
  concentration to an area of low concentration
• Permeable molecules can pass through the
  membrane freely

7
Passive Transport

• Diffusion across a membrane with no energy input
• Selectively permeable membrane

8
Facilitated Diffusion

• Transport proteins provide a pathway for certain
  molecules to pass

9
Terms

• Isos equal
• Hyper over, beyond, excessive
• Hypo under, beneath

10
Osmosis

• Passive transport of water across a selectively
  permeable membrane
• Hypertonic solution with a higher concentration
  of solute
• Hypotonic solution with the lower solute
  concentration
• Isotonic solutions in which the concentration
  of solute are equal

11
(No Transcript)
12
Osmosis Animation

• http//www.tvdsb.on.ca/westmin/science/sbi3a1/Cell
  s/Osmosis.htm

13
Active Transport

• Cell expends energy to move molecules or ions
  across a membrane
• Protein pump pumps solutes across the membrane
• Usually against the flow

14
(No Transcript)
15
Transport of Large Molecules

• Vesicles
• Small membrane sacs that specialize in moving
  products into, out of and within a cell

Exocytosis spills contents outside the
cell Endocytosis takes material into the cell
16
(No Transcript)