Download CH 107 SI Summer 2015 Worksheet 13 Answers What are the two

CH 107 SI Summer 2015
Worksheet 13 Answers
1. What are the two major types of secondary protein structure and what bonds are present in each?
α-helices and β-sheets
Hydrogen bonds
2. What types of interactions can be present in tertiary protein structure? Rank the interactions from strongest to
weakest.
disulfide bonds >> salt bridges > hydrogen bonds > hydrophilic interactions > hydrophobic interactions
3. Compare and contrast globular and fibrous proteins.
Globular
compact
functional
many amino acids
various secondary structures
water or fat soluble (not both)
Fibrous
strands, fibers
structural
few amino acids
single secondary structure
insoluble in water and fat
4. List two examples of fibrous proteins and give a brief description of each.
collagen: 3 braided strands of left-handed helices held together by H-bonds that have Gly-Pro-X repeats (found in
connective tissue)
α-keratin: 2 or 3 strands held together by disulfides to form a coiled coil (found in hair and nails)
5. List two examples of globular proteins and give a brief description of each.
myoglobin: transports oxygen in the muscles and contains an iron heme
hemoglobin: made up of four subunits held together by h-bonds or nonpolar interactions
6. What level of protein structure is present in viral capsids?
quaternary
7. Explain how perms work chemically.
Disulfide linkages in hair proteins are broken (reduced), the hair is set in the desired shape (rollers for curls), and the
proteins are then oxidized to form new disulfide bonds and give the hair a new shape.
8. What are the five methods of denaturing proteins?
heat, organics, acid, base, heavy metals, agitation