VCE Chemistry Unit 4 AOS 2: PROTEINS

An Alpha Helix, is an example of a _____________ structure.

• Quaternary

• Secondary

• Tertiary

• Primary

• Quinary

It is necessary to consume __________ amino acids, while ___________ amino acids are produced by the body.

• not-important, very important

• tertiary, quaternary

• synthetic, natural

• non-essential, essential

• essential, non-essential

Pepsin is an endopeptidase that breaks down proteins into smaller peptides. It is produced in the stomach and is one of the main digestive enzymes in the digestive systems of humans and many other animals, where it helps digest the proteins in food.

What is meant by 'denaturation"?

• Formation of a secondary structure by hydrogen bonding between partially positive -NH₂ groups and partially negative -C=O groups

• Binding of an enzyme to its complementary substrate

• Refers to when an enzyme has undergone a change in its 3D shape so it is unable to bind to act as a catalyst or bind to a substrate.

• Refers to the dipolar nature of the N-terminal and the C-terminal

• An enzyme-substrate complex

Which of the following will increase the rate of an enzyme catalyzed reaction?

• Increasing concentration of substrate

• Decreasing concentration of enzymes

• Increasing pH

• Decreasing temperature

Which of the following is not present in a tertiary structure?

• Covalent bonding between C=O and NH

• Ionic bonding between COO- and NH₃+

• Disulphide bridges

• Amide groups

Polypeptides are formed by __________ reactions. Choose all that apply.

• Esterification

• Condensation

• Substitution

• Polymerisation

• Combustion

The C-terminus is located towards the left end of a polypeptide chain.

• True

• False

Which of the following statements about enzymes is not true? (VCAA, 2009)

• Enzymes can only be denatured by an increase in temperature.

• Enzymes may form temporary ion-dipole bonds with substrate molecules.

• Enzymes speed up reactions by holding substrate molecules in positions necessary for reaction.

• The tertiary structure of an enzyme may be altered if one amino acid in its primary structure is substituted for another, different amino acid.