Cell and organelle membranes are made of two layers - lipid bilayers. - PowerPoint PPT Presentation

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Cell and organelle membranes are made of two layers - lipid bilayers.

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Cell Membranes Cell and organelle membranes are made of two layers - lipid bilayers. Cell membranes are semipermeable It acts like a screen by letting some chemicals ... – PowerPoint PPT presentation

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Title: Cell and organelle membranes are made of two layers - lipid bilayers.


1
Cell 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.

3
Passive Transport
  • The random movement of particles from a greater
    to a lesser concentration.
  • Uses no energy.
  • Three types
  • Diffusion
  • Osmosis
  • Facilitated diffusion

4
Diffusion
  • 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.

5
Simple 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.

9
Facilitated 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
12
To 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?

13
Active 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

14
ACTIVE 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.

16
This is an example of Molecular Transport
17
Bulk Transport
  • Movement of large molecule or clumps of material
    by movement of the cell membrane.
  • Two main types
  • Endocytosis
  • exocytisis

18
Endocytosis
  • process of taking material into the cell by
    infoldings or pockets of the cell membrane

19
A 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!

20
(No Transcript)
21
Exocytosis
  • 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.

22
Other terms to know about osmosis
  • Isotonic Hypertonic Hypotonic

23
Isotonic Concentration of solutes(molecules) is
the same inside and out of the cell. Water moves
equally in and out of cell.
24
Hypertonic Solution has higher solute
concentration than the cell. Water moves out of
cell.
25
Hypotonic Solution has lower solute
concentration than the cell. Water moves into
cell.
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