Chapter 3 - Amino Acids

Question 1

zwitterion

Answer 1

dipolar ion; can act as either an acid or base; overall net zero charge, but molecule contains positively and negatively charged regions

Question 2

isoelectric point

Answer 2

characteristic pH at which the net electric charge is zero (pI)

Question 3

side chain

Answer 3

R group of an amino acid; vary in structure, size and electric charge which influence the solubility of the amino acid in water

Question 4

sequence (of a protein)

Answer 4

order of amino acids in a polypeptide chain

Question 5

peptide

Answer 5

two or more amino acids joined by a peptide bond

Question 6

protein

Answer 6

polypeptide with a molecular weight above 10,000

Question 7

conjugated protein

Answer 7

protein that contains permanently associated chemical components in addition to amino acids

Question 8

prosthetic group

Answer 8

non-amino acid part of a conjugated protein

Question 9

primary structure

Answer 9

description of all covalent bonds (mainly peptide bonds and disulfide bonds) linking amino acid residues in a polypeptide chain

Question 10

secondary structure

Answer 10

the particularly stable arrangements of amino acid residues giving rise to recurring structural patterns

Question 11

tertiary structure

Answer 11

all aspects of the three-dimensional folding of a polypeptide

Question 12

quaternary structure

Answer 12

arrangement of polypeptide subunits in space when a protein has two or more subunits

Question 13

electrophoresis

Answer 13

important technique for the separation of proteins based on the migration of charged proteins in an electric field

Question 14

concensus sequences

Answer 14

sequence that reflects the most common base or amino acid at each position when a series of related nucleic acid or protein sequences are compared; contains much of the functional information in protein sequences; parts of the sequence that have particularly good agreement often represent evolutionarily conserved functional domains

Question 15

cation-exchange chromatography

Answer 15

column matrix that contains negatively charged polymer beads that cause positively charged proteins to migrate more slowly through the column

Question 16

anion-exchange chromatography

Answer 16

column matrix that contains positively charged polymer beads that cause negatively charged proteins to migrate more slowly through the column