Transcript The Plasma Membrane and Cell Transport

The Plasma Membrane and
Cell Transport
Biology
Sections 7.2 and 8.1
Plasma Membrane
 Plasma membrane - flexible boundary
between a cell and its environment.
Inside Cell
Outside
Cell
What is the nickname of the
Plasma Membrane?
The “Gate Keeper”
Because it maintains homeostasis by
controlling what enters and leaves the cell.
What does selectively
permeable mean?
 Membrane allows some molecules to
pass while keeping others out.
 Kind of like the screen on your window.
Structure of the Plasma
Membrane.
 Made of phospholipids like the one
below:
Phospholipid
 Phospholipid is made of glycerol
backbone, two fatty acid tails and a
phosphate group.
Glycerol
Backbone
Nonpolar
tails (fatty
acids)
Polar head
(includes
phosphate
group)
Phosholipid Bilayer
 There are two layers of phospholipids
back to back, making the plasma
membrane a phospholipid bilayer.
Model of the Plasma
Membrane
 Fluid Mosaic Model
What can be found in the
Plasma Membrane
 Proteins (Transport Proteins)
 Cholesterol - for stabilizing the
phospholipids.
 Carbohydrates - identify chemical
signals.
Transport Proteins
Cholesterol
Carbohydrates
Carbohydrates
Plasma Membrane Activity
Color/draw the plasma membrane.
Transport Across the Plasma
Membrane
2 Main Types
1. Passive Transport 


Moves things with their concentration gradient.
No energy needed!
2. Active Transport 

Moves things against their concentration
gradient.
Requires energy!
What is a concentration
gradient?
Passive Transport
Moves things from high to low
concentration.
 Diffusion - simple movement from high to
low concentration. No ENERGY required!
 Osmosis - diffusion of water across a
selectively permeable membrane. (No
ENERGY required!)
 Facilitated Diffusion - passive transport using
a channel or carrier protein. (still does not
require energy)
Diffusion
Osmosis
Osmotic Pressure
Turgor Pressure - pressure of the water in a full
vacuole of a plant cell against the cell wall.
Active Transport
 Protein pump used to move particles
from low to high concentration.
Na+ K+
Transport of Large Particles
 Endocytosis - process by which a cell
surrounds and takes in material.
(Requires ENERGY)
 Exocytosis - the explusion or secretion
of a material from a cell. (Requires
ENERGY)
Endocytosis
Exocytosis