Mechanisms of passive transport

1.

MECHANISMS OF PASSIVE
TRANSPORT

2.

Lesson objectives
To explain the mechanism of passive
transport.

3.

How cell regulates the
transport of the molecules through
the membrane ?

4.

Types of transport of materials
through the cell membrane
1) passive transport
2) active transport

5.

PASSIVE TRANSPORT
Passive transport is a movement materials across
cell membranes without need of energy input.
It moves by gradient of concentration: from area
of high concentration to the area of low
concentration till the concentration is equal in
both sides.

6.

Gradient of concentration
Concentration gradient is
difference in concentration of
substances between two
regions.
Ex: concentration gradient of
CO2 in alveoli and capillaries
that surround them is different:
CO2 is higher in capillaries than
in alveoli so it moves from
capillaries to alveoli.

7.

Types of passive transport
There are 3 types of passive transport:
1) simple diffusion
2) facilitated diffusion
3) osmosis

8.

1) Simple diffusion
Movement of small molecules by
concentration gradient directly across
cell membrane without help of transport
proteins.

9.

2) Facilitated diffusion
Movement of small molecules by
concentration gradient directly across cell
membrane with the help of transport
proteins.
Transport proteins are:
-channel proteins
-carrier proteins

10.

Channel proteins
Lipoproteins
Act as a gate that close and open under
specific conditions
Transport ions (Na, K, Ca, Cl)

11.

Carrier proteins
Integral glycoprotein
Attach to molecules in one side and
released to other side
Change its shape during transportation
Usually carry specific molecule

12.

3)Osmosis
Osmosis is a process by
which the molecules of a
solvent (water) pass from
a solution of low
concentration to a
solution of high
concentration through a
semi-permeable
membrane.
Water, like other
substances, moves from an
area of high concentration
to one of low
concentration.

13.

Osmosis
Water passes trough the plasma
membrane:
Directly through cell membrane
Aquaporins (channels for water, they
provide rapid movement of water)

14.

Let’s do the activity on p. 63

15.

Homework
Read p.62-63
Answer to literacy questions on p 63
Do research time on p63.
New words