#Question id: 723
#Unit 1. Molecules and their Interaction Relevant to Biology
Common structural elements in proteins such as α-helices or β-sheets are characterized by uniformly repeating, energetically favorable main chain conformations which additionally exhibit a completely saturated hydrogen-bonding network of the main chain NH and CO groups. Although polyproline or polyglycine type II helices (PPII or PGII ) are frequently found in proteins, they are not considered as equivalent secondary structure elements. Which of the following statements are correct about PP and PGs.
A. PGII -like helices form hexagonal bundles which appear to fulfill the criterion of a (largely) saturated hydrogen-bonding network of the main-chain groups
B. main chain NH and CO groups of the central PGII -helix are saturated by either intra- or intermolecular hydrogen-bonds, resulting in a self-contained hydrogen-bonding network
C. The formation of the right-handed PPI helix is possible only with proline residues because of the required cis conformation.
D. PPII helices seem to be stabilized by main chain-water hydrogen bonds (in the absence of main chain- main chain H-bonds), and tend to have a regular pattern of hydrogen bonds with water. After this, it is not surprising, that PPII helices are found mostly on the protein surface.
#Question id: 816
#Unit 1. Molecules and their Interaction Relevant to Biology
Protein stability primarily depends on
#Question id: 9164
#Unit 9. Diversity of Life Forms
Use the following figures to answer the question below.
East of the Mississippi River, in Hopkinsville Kentucky, the mean annual precipitation is 130 cm. The mean annual temperature is 14.3°C. In the winter, the mean temperature is 7.3°C, while in summer it is 20.6°C. Using the climograph shown here, how would we classify the biome found in Hopkinsville?
#Question id: 12040
#Unit 7. System Physiology – Animal
#Question id: 22940
#Unit 5. Developmental Biology