1. At pH 7, the net charge of lysine is A. -2 В. -1 С. О D. +1 Е. +2 2. All 20 amino acids have A. one chiral carbon В. one a-carbon C. one carboxyl group D. ionizable R group E. neutral charge at...

Extracted text: 1. At pH 7, the net charge of lysine is A. -2 В. -1 С. О D. +1 Е. +2 2. All 20 amino acids have A. one chiral carbon В. one a-carbon C. one carboxyl group D. ionizable R group E. neutral charge at physiological pH 3. The a helix structure of a polypeptide is maintained by A. peptide bonds B. van der Waal's force C. hydrogen bonds D. ionic bonds E. disulphide bonds 4. Which side chain of the following amino acid is deprotonated at pH 9? A. Methionine B. Alanine C. Isoleucine D. Histidine Е. Тyгosine 5. How many chiral carbons are in the following sugar? А. 1 В. 2 С. 3 D. 4 Е. 5


Extracted text: 6. Which structure is B-ribofuranose? А. В. ÇH2OH ÇH2OH ÇH2OH OH H OH H OH OH H С. D. ÇH2OH он Он .O. H. CH2OH H H OH OH OH OH Е. ÇH2OH он H. H. OH OH 7. Which pair of carbohydrates is a C-2 epimer? А. сно сно В. сно сно OH OH OH OH OH но но -H но -H H- OH H OH HO- но но- но- но H CH2OH CH2OH CH2OH CH,OH С. D. ÇHO сно CHO сно OH OH H OH H OH но -H но- но -OH OH он OH -OH OH но- -OH но- -H CH2OH CH2OH CH2OH CH2OH E. сно ÇHO H OH но но но- OH H- OH OH H- OH CH2OH CH2OH