BIOL107 Lecture Notes - Cardiac Muscle, Exocytosis, Clathrin

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL107
• Professor: Mike Harrington

Document Summary

Proteins function in variety of ways: (see fig. Some are peripheral; include receptor proteins for hormones, matrix of structural proteins that attach to membrane and provide shape, etc. Diffusion and size limits: diffusion is the driving force for substances to move around in cells, diffusion results from random motion of molecules. If some regions more concentrated than others, diffusion will tend to cause equilibrium (see text fig. 8. 9): einstein"s equation for diffusion in 2 dimensions: d2 = 6dt (d = distance traveled; t = time; d = diffusion coefficient characteristic for each type of substance) Sample calculations: for sucrose, d = 2. 38 x 10-6 cm2/sec. 1 m = 102 cm: plug in values and solve: For 1 m cell: t = 0. 7 x 10-3 sec, or 0. 7 millisecond. For 10 m cell: t = 0. 07 sec, or 70 millisecond. Osmosis and water balance: water flows smoothly across cell membranes without needing any carrier = osmosis.