Proteins: Polypeptides and Their Functions
Proteins are the working molecules of the cell — they transport nutrients, defend against infection, transmit signals, and catalyse metabolism. This quiz tests your grasp of Lesson 7 from the Biomolecules unit.
You will be examined on:
- The polypeptide backbone and peptide bonds linking amino acids
- Why proteins are heteropolymers built from twenty amino acid types
- Essential versus non-essential amino acids and dietary sources
- Functions from Table 9.5 — collagen, trypsin, insulin, antibody, receptor, GLUT-4
- Abundance facts: collagen in the animal world and RuBisCO in the biosphere
Read each question carefully; the difficulty is medium, so expect application as well as recall.
Q1. Proteins are best described structurally as:
The lesson states plainly that proteins are polypeptides — linear chains of amino acids linked by peptide bonds.
Q2. A protein is called a heteropolymer rather than a homopolymer because:
A homopolymer has only one type of monomer repeating n times; proteins draw on twenty amino acid types, so they are heteropolymers.
Q3. Which of the following is NOT listed in the lesson as an example of an amino acid?
Alanine, cysteine, proline, tryptophan and lysine are named as amino acids; glucose is a monosaccharide, not an amino acid.
Q4. Essential amino acids are those which:
The lesson explains that essential amino acids have to be supplied through our diet, while non-essential ones are those our body can make.
Q5. According to the lesson, dietary proteins are important because they are:
The text states: hence, dietary proteins are the source of essential amino acids.
Q6. Collagen, as listed in Table 9.5, functions as:
Table 9.5 lists collagen as the intercellular ground substance.
Q7. Trypsin is classified in Table 9.5 as:
Table 9.5 lists trypsin as an enzyme.
Q8. Insulin is described in Table 9.5 as:
Table 9.5 lists insulin as a hormone.
Q9. The function of an antibody, according to Table 9.5, is to:
Table 9.5 lists antibody as fighting infectious agents.
Q10. Receptors are proteins associated in Table 9.5 with:
Table 9.5 lists receptor as responsible for sensory reception (smell, taste, hormone, etc.).
Q11. GLUT-4 is a protein that:
Table 9.5 lists GLUT-4 as enabling glucose transport into cells.
Q12. Which protein is described as the most abundant protein in the animal world?
The lesson states that collagen is the most abundant protein in the animal world.
Q13. RuBisCO is described in the lesson as the most abundant protein in:
Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO) is the most abundant protein in the whole of the biosphere.
Q14. The positional information in a protein — which amino acid is first, which is second, and so on — is called its:
The lesson defines the sequence of amino acids, the positional information, as the primary structure of a protein.
Q15. In the average composition of cells given in Table 9.4, proteins account for roughly:
Table 9.4 gives proteins as 10 to 15 percent of total cellular mass, second only to water at 70 to 90 percent.