November 19, 2015
Bell Work:
 What is a concentration gradient?
Objective:
The student will be able to…
1. Distinguish between active and passive transport.
2. Explain the function of a sodium-potassium pump and
explain its importance.
3. Describe endocytosis and exocytosis.
Today in History
 1863
President Abraham Lincoln delivered the
Gettysburg Address as he dedicated a national
cemetery at the site of the Civil War battlefield in
Pennsylvania.
 1919
The Senate rejected the Treaty of Versailles.
Attendance and
Passes
Cell Transport
Active Transport
Active Transport
 The
transport of a substance across the cell
membrane against its concentration gradient.
 Requires
the use of energy
 Supplied
by ATP
 adenosine
triphosphate
Active Transport
 Can
use carrier proteins, but transports substances
against their concentration gradient
 Called
pumps
Sodium Potassium Pump
 Found
in animal cells
 In
a complete cycle, it transports three sodium ions
out of a cell and two potassium ions into a cell
 Na+
 K+
(sodium)
(potassium)
 Carrier
protein
Sodium Potassium Pump
 Sodium
ions have a higher concentration outside of
the cell
 Potassium ions have a higher concentration inside a
cell
 Actively transports both sodium and potassium
 Energy used to power the sodium potassium pump is
ATP
Sodium-Potassium Pump
1.
2.
3.
4.
Three sodium ions inside the cell bind to the sodium
potassium pump. A phosphate group is removed from ATP
and also binds to the pump.
The pump changes shape, transporting the 3 Na+ ions across
the cell membrane and releasing them outside the cell.
Pump is exposed to the surface of the cell. 2 K+ ions outside
the cell bind to the pump. The phosphate group is released
causing the carrier protein to change shape.
The pump is exposed to the inside of the cell. The 2 K+ ions
are transported across the cell membrane and released
inside the cell.
Sodium Potassium Pump
Movement in Vesicles
 Many
substances are too large to be transported by
carrier proteins
 Proteins
 Polysaccharides
 Moved
across the membrane in vesicles
Endocytosis

Movement of a substance into a cell by a vesicle
1.
Cell membrane forms a pouch around a substance.
2.
Pouch closes and pinches off from the membrane
to form a vesicle

May fuse with lysosomes or other organelles.
Endocytosis
Exocystosis
 Movement
of a substance from the inside of a cell to
the outside of a cell
 Vesicles
fuse with the cell membrane, releasing their
contents.
 Use
exocytosis to export proteins that are modified
by the Golgi Apparatus
Exocytosis
Membrane Receptor Proteins
 Proteins
body
used to communicate with other cells in the
Receptor Proteins
A
protein that binds to a specific signal molecule,
enabling the cell to respond the signal molecule
 Most
are embedded in the lipid bilayer of the cell
membrane
 The
portion of the protein that fits the signal molecule
faces the outside of the cell
Function of Receptor Proteins
 Changes
in permeability
 When
coupled with an ion channel, the binding of a signal
molecule to the receptor protein causes the ion channel to
open.
 Important
in the nervous system
Function of Receptor Proteins
Functions of Receptor Proteins
 Second
Messengers
 When
activated, acts as a signal molecule in the cytoplasm
 Amplifies the signal of the first messenger
 Can change function of the cell by:
 Activating
enzymes
 Triggering
a series of biochemical reactions in a cell
 Change
permeability by opening ion channels in the cell membrane.
Function of Receptor Proteins
Function of Receptor Proteins
 Enzyme
 Act
Action
as an enzyme
 When
a signal molecule binds to a receptor protein, it may
speed up chemical reactions inside the cell
 Activate
 Triggers
other enzymes
other chemical reactions within a cell
In Da ClubMembranes and
Transport
Vocabulary
Worksheet
Complete the
Worksheet
Cell Transport
Worksheet
Complete the
questions using a
complete
sentence.
Ticket Out
 What
is active transport?