Cell (Plasma)Membrane

All cells acquire the molecules and ions they need from their surrounding extracellular fluid. There is constant “traffic” of substances moving across the membrane.

Moving Substances Across the Cell Membrane

The cell membrane functions as a semi-permeable or selectively-permeable barrier. This means it allows very few molecules across it while keeping the majority of organically produced chemicals inside the cell.

Types of Transport

Diffusion

Molecule Movement of Diffusion

Simple Diffusion

Facilitated Diffusion

http://w3.dwm.ks.edu.tw/bio/activelearner/05/images/ch05c3.gif

Membrane Proteins

Channel Proteins

http://mywebpages.comcast.net/epollak/PSY255_pix/ion_channels.JPG

Ion Channels

http://homepage.psy.utexas.edu/homepage/class/Psy332/Salinas/Electrophysiology/channels.gif

K+ Ion Channels

Facilitated Diffusion of Glucose

Osmosis

http://www.biologycorner.com/resources/osmosis.jpg

Isotonic Solution

http://www.biologycorner.com/resources/isotonic.gif

Hypotonic Solution

http://www.uic.edu/classes/bios/bios100/summer2003/hypot.jpg

Hypertonic Solution

http://www.uic.edu/classes/bios/bios100/summer2003/hypert.jpg

Red Blood Cells in Hypotonic Solution

http://www.biosci.ohiou.edu/introbioslab/Bios170/170_3/09009jwa.jpg

Red Blood Cells in Hypertonic Solution

www.biosci.ohiou.edu/.../ 170_3/09014jwa.jpg

Movement of Water

Red Blood Cells in Solution

Plant Cells in Solution

Plasmolyzed ElodeaTurgid Elodea

Active Transport

• Movement of molecules across the cell membrane that requires energy.

• Source of energy: ATP

Sodium/Potassium Pump

Endocytosis and Exocytosis

Exocytosis

Exocytosis

http://www.accessexcellence.org/RC/VL/GG/images/Fig_14.25.jpg

http://www.uccs.edu/~rmelamed/MicroFall2002/Chapter%2010/Endocytosis.jpg

Endocytosis

Receptor-Mediated Endocytosis

http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio02.swf::Endocytosis%20and%20Exocytosis

Cell Signaling

http://www.scq.ubc.ca/conversing-at-the-cellular-level-an-introduction-to-signal-transduction/