Chapter 12 (12.1 - 12.5)

Question 1

amino acid

Answer 1

• made up of an amino group (amine), side chain, a hydrogen, and a carbonyl group (carboxylic acid)

Question 1

amino acid pH

Answer 1

7

Question 2

pH changes in amino acids

Answer 2

carbonyl/carboxylic acid; ACIDIC (donates protons)
amines/amino group; BASIC (accepts protons)
- due to this, groups are always effected by pH changes

Question 3

amino acid classification

Answer 3

• nonpolar
• polar/neutral
• acidic
• basic

Question 4

nonpolar AA’s

Answer 4

side-chain only contains alkyl groups
*exception - proline

Question 5

polar-neutral AA’s

Answer 5

side-chain contains sulfur or oxygen atoms

Question 6

acidic AA’s

Answer 6

side-chain contains attached carboxylic acid (negatively charged - donates protons)

Question 7

basic AA’s

Answer 7

side-chain contains attached nitrogen atoms (+ charged - accepts protons)

Question 8

D/L amino acids

Answer 8

D-AA’s: NH3 on the RIGHT SIDE
L-AA’s: NH3 on the LEFT SIDE

Question 9

peptide bond

Answer 9

amide bone (C-N) linking 2 amino acids

Question 10

N-terminus

Answer 10

end with the free amino group (LEFT)

Question 11

C-terminus

Answer 11

end with the free carbonyl group (RIGHT)

Question 12

net charge

Answer 12

will change if the pH is changed

Question 13

net +/- charge

Answer 13

will allow the peptide to be soluble
- pH 1 - net charge 2+
- pH 7 - net charge 0
- pH 14 - net charge 2-

Question 14

protein classification

Answer 14

• fibrous
• globular

Question 15

fibrous proteins

Answer 15

• thin/long/stringlike
• found in skin or hair
• tough and water-insoluble

Question 16

globular proteins

Answer 16

• spherical proteins
• highly folded
• water soluble

Question 17

primary structure

Answer 17

order of amino acid residues (AA sequence)

Question 18

secondary structure

Answer 18

how SEGMENTS of protein chain is folded, twisted, or bet
- often seen through H-bonding: b/w N-H or C=O

Question 19

types of secondary structure

Answer 19

• alpha-helix
• beta-sheet

Question 20

beta sheet

Answer 20

strands of polypeptide chain aligned side-to-side
- PARALLEL SHEETS
- ANTIPARALLEL SHEETS

Question 21

alpha helix

Answer 21

coiled spring shape
between N-H or C-O (H-bonding)

Question 22

tertiary structure

Answer 22

overall 3-D shape
- held in place by covalent and noncovalent interactions

Question 23

noncovalent interactions

Answer 23

• H-bonding
• ionic bonding
• hydrophobic effect

Question 24

h bonding

Answer 24

between N-H/O-H or N-O

Question 25

ionic bonding

Answer 25

known as "salt bridge" between positive and negative charged side chains

Question 26

hydrophobic effect

Answer 26

nonpolar molecules drawn together to avoid water; fold to the INTERIOR of the protein

Question 27

covalent interactions

Answer 27

- disulfide bridge between 2 cysteine residues; thoil groups oxidize into a disulfide bond

Question 28

quaternary structure

Answer 28

found only in proteins with more than one polypeptide chain - held by noncovalent interactions and disulfide bonds - help regulate protein activity

Question 29

prosthetic groups

Answer 29

non AA components - heme group or metal ions

Question 30

simple proteins

Answer 30

don't need prosthetic groups

Question 31

conjugated proteins

Answer 31

need prosthetic groups

Question 32

denaturation

Answer 32

any change in protein conformation - disruption of noncovalent interactions - loss of structure - generally irreversible

Question 33

denaturants

Answer 33

factors that can disrupt one or more noncovalent interactions

Question 34

examples of denaturants

Answer 34

- heat - detergents - organic compounds - pH change - inorganic salts