BIOL 112 Lecture 6: Lecture 6 - Cells.pdf

• School: McGill University
• Department: Biology
• Course: BIOL 112
• Professor: Frieder Schoeck

Document Summary

Diffusing molecules don"t travel long distances because of their random walk ! Big molecules travels 10 micrometers in 1s (distance = 10 * sqrt 1) ! Cells are very small because most chemical reactions in cells require diffusion ! Distance travelled is proportional to square root of time ! Volume increase much faster than surface area (volume: factor of 3, surface area: factor of 2) ! Surface area: volume ration is also important for waste management! Surrounded by the nuclear envelope; two membranes ! Dna is transcribed into mrna or rrna by rna polymerasein the nucleus ! Rrna is not translated; it directly folds into a 3d structure ! Rna is later translated into proteins by ribosomes in the cytoplasm ! Ribosomes are made of 4 rrnas and about 80 proteins and assembled in the nucleolus. Materials transported into/ out of nucleus via nuclear pores! (rnas largely determine structure and function) ! chloroplasts !