Fig. 2.1 presents a transmission electron micrograph of this bacterium. Name the bacterium responsible for cholera.
The bacterium shown in Fig. 2.1 is a prokaryotic cell. Each description A to C refers to a cell structure found in both prokaryotic cells and plant cells. For each of A to C: name the structure described, and state one difference between a prokaryotic cell and a plant cell for that structure. A: the site where polypeptides are synthesised. B: the cell's genetic material. C: the rigid outer structure that keeps the cell in shape and prevents osmotic lysis.
Cholera is one example of an infectious disease. Explain what the term infectious disease means.
The symptoms of cholera are caused by choleragen, a toxin released by the bacterium. Choleragen is a protein composed of six polypeptides: one polypeptide called the A subunit, which contains an extended alpha helix, and five polypeptides that together form the B subunit. List the levels of protein structure present in choleragen.
Outline the process by which choleragen enters the cell. You may use the space for annotated diagrams.
Suggest why subunit B is chosen instead of subunit A for the vaccine.
Outline how this vaccine can protect against cholera.