Lecture 1.5 - Proteins

Question 1

proteins

Answer 1

polymers made up of 20 different amino acids in different proportions and sequences

Question 2

amino acid structure

Answer 2

central carbon atom (alpha carbon) bonded to an amino group, carboxyl group, and a hydrogen atom
amino and carboxyl are charged at physiological ph (7-7.4)

Question 3

charged side chains

Answer 3

+1 or -1 side chains
hydrophilic
attract oppositely charged ions of biomolecules

Question 4

polar but uncharged

Answer 4

hydrophilic
tend to form H-bonds with polar biomolecules

Question 5

nonpolar side chains

Answer 5

hydrophobic
cluster together in the interior of the protein

Question 6

cysteine

Answer 6

the terminal group is cysteine side chains can react with another cysteine side chain to form a disulfide bond

Question 7

peptide

Answer 7

two or more amino acids joined together by peptide bonds

Question 8

peptide bonds

Answer 8

formed by condensation reactions between the carboxyl and amino groups

Question 9

direction of synthesis

Answer 9

polypeptide chains are synthesized from the amino acid to the carboxyl terminus (N –> C)

Question 10

primary structure

Answer 10

specific sequence of amino acids

Question 11

secondary structure

Answer 11

regular, repeated spatial patterns in different regions of a polypeptide chain
formed by hydrogen bonding between atoms on the “backbone” of the polypeptide

Question 12

tertiary structure

Answer 12

three-dimensional shape of a folded polypeptide chain
determined by interactions between amino acid side chains (hydrogen bonding, hydrophobic effect, van der Waals forces, ionic interactions, disulfide bond)

Question 13

quaternary structure

Answer 13

interactions of subunits by various interactions

Question 14

amino acid order

Answer 14

dictates how the protein will fold into ultimate three-dimensional structure

Question 15

proteins folding

Answer 15

occurs spontaneously
determines the function of a protein
MISfolding can lead to disease
some require chaperons to assist folding

Question 16

amino acids interaction

Answer 16

nonpolar amino acids tend to fold into the center of the protein whereas polar residues tend to be on the exterior in water

Question 17

____ interactions allow a protein to bind to another molecule

Answer 17

noncovalent

Question 18

protein binding

Answer 18

proteins can change their shape when they bind to other molecules

Question 19

environmental conditions

Answer 19

high temp. effects H-bonding and hydrophobic interaction
pH change effects ionization pattern of exposed R groups
high concentration of polarity effect H-bonds
non-polar substances effect hydrophobic interaction