Understanding Proteins and Enzymes

What is the function of enzymes in living things?

• increase the rate of chemical reactions

• form the basis of the plasma membrane

• main energy molecule for a cell

• insulation and protection

Which of the following levels of protein structure is characterised by the sequence of amino acids in a polypeptide chain?

• Secondary structure

• Primary structure

• Tertiary structure

• Quaternary structure

What is the main function of enzymes in biological systems?

• To provide structural support

• To store genetic information

• To catalyse biochemical reactions

• To transport oxygen

Which of the following factors does NOT affect enzyme activity?

• Temperature

• pH

• Substrate concentration

• Colour of the enzyme

What type of bond is primarily responsible for the secondary structure of proteins?

• Ionic bonds

• Hydrogen bonds

• Covalent bonds

• Disulfide bridges

Enzymes are highly specific. What does this mean?

• They can catalyse any reaction

• They only work at high temperatures

• They only catalyse one type of reaction

• They are not affected by pH

Which of the following best describes the quaternary structure of a protein?

• The sequence of amino acids

• The folding of the polypeptide chain into a 3D shape

• The interaction of multiple polypeptide chains

• The formation of alpha helices and beta sheets

What is the role of disulfide bridges in protein structure?

• They stabilize the primary structure

• They stabilize the secondary structure

• They stabilize the tertiary structure

• They stabilize the quaternary structure

Which of the following is a characteristic of the tertiary structure of proteins?

• Linear sequence of amino acids

• Formation of alpha helices and beta sheets

• Three-dimensional folding pattern

• Interaction of multiple polypeptide chains

How do enzymes lower the activation energy of a reaction?

• By increasing the temperature of the reaction

• By providing an alternative reaction pathway

• By changing the pH of the environment

• By increasing the concentration of substrates