This is
gonna be
hard
work!!
Active Transport
cell does use energy
1. Protein Pumps
2. Endocytosis
3. Exocytosis
high
low
Active transport
• Energy is required for carriers to transfer
substance uphill against a concentration
gradient
Ex: uptake of iodine by thyroid gland cells
TYPES OF ACTIVE TRANSPORT
PRIMARY ACTIVE TRANSPORT
SECONDARY ACTIVE
TRANSPORT
Primary active transport
 Energy is required directly to move a substance
uphill
 Hydrolysis of ATP by the transporter provides
the energy for primary active transport

Major primary active transport proteins found
in cells are
1 Na+/K+ ATPase
2. Ca2+ ATPase
3. H+ ATPase
4. H+/K+ ATPase
Sodium –potassium pump
- Is present in all the cells of the
body
- Responsible for maintaining the Na+
and K+ concentration difference
across the cell membrane
- Establishment of negative electrical
potential inside the cell
 The sodium-potassium pump (a
membrane protein) exchanges three
Na+ ions for two K+ ions.

Functions of Na+ -K+ pump
1. CONTROLLING THE CELL VOULUME
2. ELECTOGENIC ACTIVITY
CALCIUM PUMP
Secondary active transport
• In this type, transport of substances are coupled
to the primary active transport
• Usually secondary transporters utilize sodium
Ex: Primary active transport of Na+ by Na+/K+
ATPase, creates sodium conc gradient across
plasma membrane which indirectly stores
energy for secondary active transport
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Transport of large molecules
• Macromolecules that are too large move in or out
of the cell with the aid of bubble like vesicles
created from cell membrane
Basic mechanisms are as follows
• Endocytosis: Very large particles enter the cell
The principal forms of endocytosis are
pinocytosis and
• Exocytosis
phagocytosis
ENDOCYTOSIS
is the case when a molecule causes the cell
membrane to bulge inward, forming a vesicle.
PHAGOCYTOSIS
is the type of endocytosis where an entire cell
is engulfed.
PINOCYTOSIS
is when the external fluid is engulfed.
RECEPTOR-MEDIATED ENDOCYTOSIS
occurs when the material to be transported
binds to certain specific molecules in the
membrane.
Exocytosis:
Forces material out of cell
in bulk
• membrane surrounding the
material fuses with cell
membrane
• Cell changes shape –
requires energy
• EX: Hormones or wastes
released from cell
Carriers that move more than one kind of molecules into
or out of the cell
• If the molecules are moving in the same direction either
into or out of the cell, the process is called symport or
cotransport
• Some active transport carriers move only
one kind of molecule – uniport
• If the molecules are carried in different direction,
the process is known as antiport or counter
transport
Ex: Na+-K+ ATPase pump
5 Minutes Break
Thank you………