Biochemistry: Proteins

Question 1

charges on functional groups

Answer 1

(1) help amino acids stay in solution  interact w/ other amino acids or solutes
(2) affect chemical reactivity

Question 2

peptide bond

Answer 2

C – N covalent bond after amino acid condensation

- chain composed of < 50 amino acids linked together

Question 3

peptide bond backbone

Answer 3

(1) R-group orientation
(2) directionality
(3) flexibility

Question 4

protein

Answer 4

polymers made up of amino acids

- many fcns (depends on size & shape)

Question 5

levels of organization (protein structure)

Answer 5

(1) primary structure
(2) secondary structure
(3) tertiary structure
(4) quaternary structure

Question 6

primary structure

Answer 6

unique sequence of amino acids in a protein
- limitless primary structures

fundamental to higher levels of protein structure

Question 7

secondary structure

Answer 7

distinctively shaped sections of proteins that are stabilized by H-bonding

• possible structures
• fcns

Question 8

possible structures of secondary structure

Answer 8

(1) α-helix (alpha-helix) – coiled backbone (spiral shape) stabilized by H-bonding
(2) β-pleated sheet (beta-pleated sheet) – segments of peptide chains bend 180˚ & fold into sheet-like shape by H-bonding
* type depends on primary structure

Question 9

secondary structure fcns

Answer 9

(1) increase stability of molecule

(2) help define shape

Question 10

tertiary structure

Answer 10

overall 3D shape of single polypeptide chain

- result from multiple interactions

Question 11

tertiary structure interactions

Answer 11

(1) H-bonding
(2) hydrophobic interactions
(3) van der Waals interactions
(4) covalent bonding
(5) ionic bonding

Question 12

quaternary structure

Answer 12

overall 3D shape formed from 2+ polypeptide chains (subunits)
- could be identical subunits or not

Question 13

groups of amino acids based on their side chains

Answer 13

(1) nonpolar side chain
(2) polar side chain
(3) uncharged side chain

interactions w/ otro amino acids predictable

Question 14

nonpolar side chain

Answer 14

(1) hydrophobic – lack charged or highly electronegative atoms -> no form H-bonds w/ water
(2) no dissolve -> tend to coalesce in aq. solution
(3) lost proton -> acidic
(4) interact w/ water

Question 15

polar side chain

Answer 15

(1) hydrophilic – readily dissolve in water
(2) took proton -> basic
(3) interact w/ lipids

Question 16

uncharged side chain

Answer 16

(1) highly electronegative oxygen -> polar covalent bond -> uncharged polar
(2) interact w/ lipids

Question 17

prion

Answer 17

(proteinaceous infectious particles) proteins that can be folded into infectious, disease-causing agents

(ie) mad cow disease

Question 18

protein folding characteristics

Answer 18

(1) mostly spontaneous
(2) some proteins require chaperones
(3) some misfolding

Question 19

protein fcns

Answer 19

(1) catalyst
(2) defense - antibiotics
(3) movement - dinein kinesin
(4) signaling - insulin
(5) structure - collagen & microtubules
(6) transport - hemoglobin