Alpha helix: Difference between revisions
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c) Tracing the chain: When building a model into electron density, the first step was to place contiguous C-alpha atoms into the density (with proper spacing). To see in which direction an alpha helix goes, you look at the side chain density. If it points up, the N-terminus is on top, otherwise on the bottom. (search for Christmas tree in [http://www-structmed.cimr.cam.ac.uk/Course/Fitting/fittingtalk.html this course]) | c) Tracing the chain: When building a model into electron density, the first step was to place contiguous C-alpha atoms into the density (with proper spacing). To see in which direction an alpha helix goes, you look at the side chain density. If it points up, the N-terminus is on top, otherwise on the bottom. (search for Christmas tree in [http://www-structmed.cimr.cam.ac.uk/Course/Fitting/fittingtalk.html this course]) | ||
== Quiz == | |||
<quiz display=simple> | |||
{What level of structure does an alpha helix refer to?} | |||
-A. PRimary structure | |||
+B. Secondary structure | |||
-C. Tertiary structure | |||
-D. Quaternary structure | |||
{The alpha helix is a repetitive structure.} | |||
+A. TRUE. | |||
-B. FALSE. | |||
{Hydrogen bonds are from...} | |||
-A. n to n+1. | |||
-B. n to n+2. | |||
-C. n to n+3. | |||
+D. n to n+4. | |||
{The following amino acids are rarely found in the center of an alpha helix (more than one answer)} | |||
+A. Proline | |||
-B. Serine. | |||
+C. Glycine. | |||
-D. Alanine. | |||
{Which atoms/groups are involved in forming hydrogen bonds in alpha helices?} | |||
-A. the alpha carbons. | |||
-B. the beta carbons. | |||
+C. the carbonyl oxygen. | |||
+D. the amide group. | |||
</quiz> | |||
== References == | == References == | ||
<references/> | <references/> | ||