Chapter 4: Protein Structure and Function

Question 1

Primary

Answer 1

Amino Acid sequence
- forms peptide bonds

Question 2

Secondary

Answer 2

stable folding patterns within a polypeptide
-hydrogen bonds
- alpha helix and beta sheets

Question 3

Tertiary

Answer 3

domains and full 3D conformation

Question 4

Quaternary

Answer 4

Complete structure of a complex formed between more than one polypeptide chain

Question 5

Secondary structure: What stabilizes these structures?

Answer 5

hydrogen bond between the amino and carbonyl group in the polypeptide backbone

Question 6

Alpha Helix

Answer 6

carbonyl group of one peptide bond is hydrogen bonded to the amino group of a peptide bond 4 amino acids away.

Question 7

How often does alpha helix have a complete turn?

Answer 7

3.6 amino acids

Question 8

What kind of amino acids must compose a alpha helix for it to be able to span the membrane bilayer?

Answer 8

non polar amino acids

Question 9

Parts of Alpha Helix

Answer 9

• hydrophilic polypeptide backbone
  hydrophobic lipid hydrocarbons

Question 10

What shape can amphipathic alpha helices form?

Answer 10

coiled coil

Question 11

Beta sheets

Answer 11

polypeptide strands are extended
- associate through hydrogen bonding between different strands

Question 12

Antiparallel Beta sheets

Answer 12

point towards each other

Question 13

parallel beta sheets

Answer 13

both face upwards

Question 14

Tertiary Structure relies on what bonds

Answer 14

weak non covalent bonds

Question 15

Modular Structure

Answer 15

one polypeptide that has regions of both alpha helix and beta sheets

Question 16

What kind of bonds enable binding of subunits?

Answer 16

weak non covalent bonds

Question 17

What energy state do properly folded proteins assume?

Answer 17

lowest energy state

Question 18

What is the only covalent bond other than peptide bonds that can form in a protein?

Answer 18

disulfide bonds

Question 19

What protein assist in protein folding?

Answer 19

molecular chaperones; chaperonins; heatshock proteins(hsps)

Question 20

What can a defect in protein folding lead to?

Answer 20

aggregation

Question 21

Disorders caused by aggregation

Answer 21

-Huntington’s
Prion Diseases
- Scrapie
Mad Cow
Creutzfeldt Jacob

Question 22

What causes sickle cell disease?

Answer 22

mutation in the 6th amino acid from Glutamic Acid to Valine

Question 23

If an enzyme has a higher affinity what is the effect on concentration?

Answer 23

Lower concentration

Question 24

3 mechanisms to lower activation energy

Answer 24

Anabolic, Rearrangements, Catabolic

Question 25

Anabolic Mechanism to Lower Activation Energy

Answer 25

enzyme binds to two substrates and orients them to encourage a reaction

Question 26

Rearrangement Mechanism to Lower Activation Energy

Answer 26

substrate binding to enzyme rearranges electrons creating partial charges that favor a reaction

Question 27

Catabolic Mechanism to Lower Activation Energy

Answer 27

enzyme strains the bound substrate forcing it to favor a reaction

Question 28

Competitive Inhibitor

Answer 28

binds to the active site

Question 29

Noncompetitive Inhibitor/ Allosteric Regulator

Answer 29

binds to the allosteric site which changes the shape of the active site

Question 30

Which form of enzyme regulation causes a conformational change?

Answer 30

reversible protein phosphorylation

Question 31

Where can phosphorylation occur?

Answer 31

Ser, Thr, and Tyr residues

Question 32

What can conformational changes with nucleotides hydrolysis be used to drive ?

Answer 32

Motors proteins - muscle contraction -Chromosome spindles -Organelle movement