BIOL 112 Lecture Notes - Lecture 8: Endomembrane System, Nuclear Membrane, Nucleolus

• School: McGill University
• Department: Biology
• Course: BIOL 112
• Professor: Joseph Dent, Frieder Schock

Document Summary

Most chemical reactions in cells require diffusion. Diffusing molecules can"t travel long distance because or their randomness. Distance traveled is proportional to square root of time. Big molecule travels 10um in 1s (distance = 10*11/2) Minutes or hours are too long for our body system reactions. Surface to volume ratio decreases as size increases. Needs greater surface area for diffusion across cell membrane efficiently. Very small with no nucleus and few membrane enclosed compartments. Nucleus has inner and outer nuclear membrane. Dna is transcribed into mrna or rrna by rna polymerases. Allow chemical reactions to occur in small spaces to allow faster reaction. Made of cellulose and does not require sodium potassium pump. Rrna is not translates, it directly folds into a 3d structure. Ribosomes are made of 4 rrna and about. Rna largely determine the structure and function. Right next to nucleus and can be continuous with outer nuclear membrane. Have a lot of ribosomes attached to it.