BIOLOGY 1A Lecture 19: Lecture - 10_3_18 - Dr.Fischer part 1
Document Summary
Mon, wed, fri (9-10 am) and thursday (2-3 pm). rfischer@berkeley. edu. Backbone composed of deoxyribose sugars connected by phosphodiester linkages. 4 nitrogenous bases - thymine, adenine, cytosine, guanine. Carbon ester o = c - o - r. Deoxyribose is a sugar with 5 carbons. Deoxy = no oxygen at the 2"-carbon. The amount of g,c,a,t varies from species to species. In all species, amount of a = amount of t. Amount of g = amount of c. Pauling and corey used x-ray diffraction to determine bond angles and distances. Allowed for generation of space filling models. A pure solution of molecules is crystallized, so the molecules are an ordered array, each one oriented in the same way. Regularly spaced atoms in the crystal deflect x-rays in an ordered pattern. The x-rays strike and darken a piece of film (spots) The arrangement of the spots is a reflection of the arrangement (bond length and angles) of the atoms in the crystal.
