BIOC12 Lec 4 Part 2

Question 1

describe what beta pleated sheets are like

Answer 1

the amino acids adopt the conformation of
sheet of paper

In polypeptide strands and parallel and anti-parallel

is stabilized by hydrogen bonds

Question 2

describe what alpha helixes are like

Answer 2

It has a rod shape. The peptide is coiled
around an imaginary cylinder and
stabilized by hydrogen bonds formed
between components of the peptide
bonds

Question 3

provide an overview of how x ray crystallography works (sl 41 and 42)***

Answer 3

In this technique, a beam of collimated, or parallel, X rays is aimed at a crystal of protein molecules. Electrons in the crystal diffract the X rays, which are then recorded on film or by an electronic detector (Figure 4.2).

Mathematical analysis of the diffraction pattern produces an image of the electron clouds surrounding atoms in the crystal. This electron density map reveals the overall shape of the molecule and the positions of each of the atoms in three-dimensional space.

By combining these data with the principles of chemical bonding, it is possible to deduce the location of all the bonds in a molecule, and hence its overall structure.

it determines the 3d or terterary strcutre