chem exam 5

12.4-12.7, 11, and 14

proteins are

-fibrous

-globular

fibrous proteins

-long strands

-skin and hair

-tough, water soluble

globular proteins

-spherical in shape

-highly folded

-they tend to be water soluble 

4 levels of protein structure

1. primary

2. secondary

3. tertiary

4. quaternary

primary structure

the order of amino acid residues

• order is listed from N terminus to C terminus

secondary structure

how segments of protein strand are folded, twisted, and bent

-forms due to H bonds between NH and C=O groups

2 types: aHelix and BSheet

A Helix

resembles a coiled string

B sheet 

forms when different segments of a polypeptide chain align side by side

tertiary structure

3D shape

-usually only one folding pattern

-surface of globular proteins usually have binding sites

HELD IN PLACE BY COVALENT AND NON COVALENT INTERACTIONS

Non Covalent Interactions

-H bonds

-Hydrophobic effect: avoid water

-Ionic bonds: salt bridge

Covalent Interaction

-Disulfide bridge 

-Important for extracellular proteins 

Which interaction occurs only at the inside of a
protein when in an aqueous solution?
a) Disulfide bridge
b) Hydrophobic effect
c) Ionic bond
d) Hydrogen bond

b) Hydrophobic effect

What is the covalent interaction involved in
keeping the tertiary structure of a protein?
a) Disulfide bridge
b) Hydrophobic effect
c) Ionic bond
d) Hydrogen bonds

d) Hydrogen bonds

quaternary structure 

-only in proteins that have more than 1 polypeptide chain

-noncovalent interactions and disulfide bonds 

-regulates protein activity 

prosthetic groups

non amino acid components

ex: heme group and several metal ions

simple proteins

function without prosthetics

conjugated proteins

require a prosthetic group

Proteins are made of:
a) Amino Acids
b) Nucleic Acids
c) Monosaccharides
d) Fatty acids

a) Amino Acids