Science & Technology in Action

1st Edition

Proteins - Essential Biomolecules

Department of Agriculture, Food and the Marine

The subject of this lesson is the function of protein in human biology. It outlines the production process by which proteins, including therapeutic human proteins are made. Nutritional sources of protein are also covered.
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Contains the full lesson along with a supporting toolkit, including teachers’ notes.

Lesson excerpt

What is a biomolecule?
Biomolecules are carbon compounds produced by living organisms. They fall into three size classes – small, medium and large. The small biomolecules, monosaccharides, amino acids, glycerol, fatty acids, nucleotides are the building blocks of the larger biomolecules.

Monosaccharides join together forming disaccharides andpolysaccharides (starch, cellulose and glycogen). Amino acids link in specific sequences forming proteins. Glycerol and fatty acids join forming lipids and with nucleotides link together forming the nucleic acids (DNA, RNA). Lipids act as the building blocks for cell membranes by organising into a double layer; these bilipid membranes perform many vital functions for cells. Our thirteen vitamins are another group of biomolecules but are chemically unrelated. 

What is a protein?
A protein is a macromolecule. It is composed of one or more chains of amino acids. Each long chain of amino acids is called a polypeptide – the chemical bond linking adjacent amino acids called a peptide bond.

The sequence of amino acids is crucial - the disease sickle cell anaemia is caused by one amino acid being in the wrong place in haemoglobin. Therefore, the system for organising the exact number and sequence of amino acids for proteins must be highly accurate and efficient. 

What are the major functions of proteins?
Proteins play important structural and metabolic roles in the human body. Enzymes (biological catalysts) and protein-based hormones regulate anabolic and catabolic reactions. Anabolic reactions are ones where complex biomolecules are made from smaller simpler ones. These reactions use up a lot of energy. Catabolic reactions are the breakdown of these large complex biomolecules in smaller ones, releasing energy. 



True or False?

  1. An organic substance is also known as a biomolecule. true
  2. Starch is a disaccharide. false
  3. A bilipid layer is the foundation of cell membranes. true
  4. Enzymes are specific biological catalysts. true
  5. Peptide bonds link glucoses in starch and cellulose. false
  6. The sequence of phosphate and sugar in DNA is the genetic code. false
  7. The position of a gene on a chromosome is called its locus. true
  8. mRNA is a complementary copy of the gene base sequence. true
  9. Protein synthesis involves transcription and translation. true
  10. Commercial production of human proteins is called farming. false
  11. The DNA base sequence is related to a protein's amino acid sequence. true
  12. Transcription and translation of a gene is known as gene expression. true