Membrane Transport

Membrane Transport

What are some substances commonly transported across membranes?

Membrane Transport

What are the three mechanisms used to move solute molecules across the membrane? Diffusion Facilitated diffusion Active transport

Simple Diffusion What is involved in this

transport process? Movement of molecules

from an area of higher concentration to an area of lower concentration without using the cell’s energy

What can cross the plasma membrane via simple diffusion?

Simple Diffusion

How does osmosis differ from simple diffusion? Osmosis is the

diffusion of water.

Simple Diffusion

What are the major factors that influence diffusion across a membrane?

Facilitated Diffusion

How is facilitated diffusion different from simple diffusion?

Facilitated Diffusion

A type of passive transport because it moves substances down their concentration gradient without using the cell’s energy.

Carrier proteins are used to transport specific substances down their concentration gradient.

Carrier Proteins

Transport proteins that can bind to specific substances on one side of the cell membrane, carry the substance across the cell membrane and release it one the other side

Facilitated Diffusion

Facilitated Diffusion

What do we specifically know about the transport of glucose in red blood cells?

Active Transport

How is active transport similar to and different from facilitated diffusion? Transport of a substance across the cell

membrane against its concentration gradient

Molecules move from a lower concentration to a higher concentration

Requires the cells to use energy (ATP)

Active Transport

What do we currently know about the sodium-potassium pump?

Sodium-Potassium Pump

Na+=sodium ions K+= potassium ions Transports 3 sodium ions (Na+) out of the

cell and 2 potassium ions (K+) into the cell Na+ concentration is higher outside the cell K+ concentration is higher inside the cell Ions move against their concentration

gradient ATP is needed Look on page 82 at Figure 4-5.

Active Transport

Active Transport

Why is this sodium-potassium pump so important for animal cells? Prevents Na+ from accumulating in the

cell and this would be toxic to the cell Helps maintain the concentration

gradients of Na+ and K+. Many cells use the Na+ gradient to help transport other substances such as glucose across the membrane.

Active Transport

Vesicles Move Substances Across Membranes

Endocytosis= the movement of a substance into a cell by a vesicle

Exocytosis= the movement of a substance by a vesicle to the outside of a cell

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/endocytosis.gif

Membrane Receptor Proteins Receive Information

Cells must respond to information and filter out unimportant information.

In order to receive messages carried by signal molecules, the cell membrane contains specialized proteins called receptor proteins that are able to bind to these molecules.

http://www.scq.ubc.ca/wp-content/uploads/2006/07/transduction.gif