Proteins Back Page

Question 1

Protein Conformations

Answer 1

• Different levels of protein structure

Question 2

Levels of protein Structures

Answer 2

1° Primary
2° Secondary
3° Tertiary
4° Quaternary

Question 3

1° (Primary) Description

Answer 3

• Rarely have a function
• A chain of more than 50 amino acids linked by peptide linkages
• Sequence and type of amino acids present varies

Question 4

1° (Primary) Chemical Bonding Involved

Answer 4

• Peptide linkage between the NH2 of one amino acid and the carboxylic acid group of the next amino acid
• No R-group interactions

Question 5

2° (Secondary) Description

Answer 5

• one or more polypeptide chains individually coiled into an alpha helix or a beta-pleated sheet
• Ex. Some parts of hemoglobin

Question 6

Beta-Pleaded Sheet Example

Answer 6

Spider Webs

Question 7

Alpha Helix Example

Answer 7

Keratin

Question 8

2° (Secondary) Chemical Bonding Involved

Answer 8

• Hydrogen bonding and a peptide link between the carbonyl and nitrogen of amino acids that are 5 amino acids apart

Question 9

3° (Tertiary) Description

Answer 9

• The folding of a coiled (helical or pleated sheet) polypeptide chain
• curl on curl
• Ex. Hemoglobin

Question 10

3° (Tertiary) Chemical Bonding Involved

Answer 10

• Hydrophilic and hydrophobic R-groups
• Hydrogen bonding between distant amino acids
• Disulfide bridges
• Prosthetic groups

Question 11

Prosthetic Groups

Answer 11

• Inorganic attachments
• Ex. Heme

Question 12

4° (Quaternary) Description

Answer 12

• The assembly of 2 or more folded helical sub-units
• Ie. 2 or more different peptide molecules
• Ex. Hemoglobin

Question 13

4° (Quaternary) Chemical Bonding Involved

Answer 13

• Hydrophobic interactions (centre of molecule)
• Hydrogen bonding
• R-group interactions (more complicated)
• Van Der Waals forces (intermolecular forces)

Question 14

Why are there Van Der Waals forces in quaternary proteins?

Answer 14

Since there’s 2 or more polypeptides

Question 15

Protein Denaturing

Answer 15

• The unraveling of a protein which could ultimately alter the proteins function
• Does not necessarily affect peptide bonds

Question 16

Factors that can cause protein denaturing

Answer 16

• Temperature
• pH
• Ion Concentration
• Presence of other reactive chemicals

Question 17

Temperature (protein denaturing factor)

Answer 17

• Extreme temperatures (especially heat) break interactions that hold together protein conformations
• Ex. High environmental temperatures or fever

Question 18

pH (protein denaturing factor)

Answer 18

• extreme pH’s can cause denaturing
• Certain proteins/enzymes have ideal pH ranges
• In humans issues come with lung and kidney disease

Question 19

Presence of other reactive chemicals (protein denaturing factor)

Answer 19

• Any chemicals that are highly reactive could disrupt interactions in proteins