LEHNINGER PRINCIPLES OF BIOCHEMISTRY: CHAPTER 3 KEY TERMS WITH CORRECT ANSWERS

amino acids CORRECT ANSWER α-Amino-substituted carboxylic acids, the building blocks of proteins. residue CORRECT ANSWER A single unit in a polymer; for example, an amino acid in a polypeptide chain. The term reflects the fact that sugars, nucleotides, and amino acids lose a few atoms (generally the elements of water) when incorporated in their respective polymers. R group CORRECT ANSWER (1) Formally, an abbreviation denoting any alkyl group. (2) Occasionally, used in a more general sense to denote virtually any organic substituent (e.g., the R groups of amino acids). chiral center CORRECT ANSWER An atom with substituents arranged so that the molecule is not superposable on its mirror image. enantiomers CORRECT ANSWER Stereoisomers that are nonsuperposable mirror images of each other. absolute configuration CORRECT ANSWER The configuration of four different substituent groups around an asymmetric carbon atom, in relation to ᴅ- and ʟ-glyceraldehyde. ᴅ, ʟ system CORRECT ANSWER Make sure that the molecule is drawn as the Fischer projection in which the carboxylic acid group is on top and the side chain on bottom. If the amine group is on the right of the carbon chain, assign the label ᴅ to the compound; if it is on the left of the carbon chain, assign the label ʟ. polarity CORRECT ANSWER (1) In chemistry, the nonuniform distribution of electrons in a molecule; polar molecules are usually soluble in water. (2) In molecular biology, the distinction between the 5' and 3' ends of nucleic acids. absorbance, A CORRECT ANSWER A measure of the capacity of a substance to absorb light of a specified wavelength. It is equal to the logarithm of the reciprocal of the transmittance