Discuss with your teacher what does 'a suitable gene' means, in the context of DNA vaccines.
In the context of DNA vaccines, 'a suitable gene' refers to a gene that codes for antigenic polypeptides or antigenic proteins of the pathogen.
Using recombinant DNA technology, such a suitable gene can be produced in bacteria or yeast. When introduced into the body through vaccination, the antigenic proteins produced from this gene trigger the immune system to produce antibodies. These antibodies would neutralise the pathogenic agents during actual infection. Additionally, the vaccines generate memory B and T-cells that recognise the pathogen quickly on subsequent exposure and overwhelm the invaders with massive production of antibodies. An example is the hepatitis B vaccine produced from yeast.
Explanation
The question asks about 'a suitable gene' in DNA vaccines. From the context, we learn that recombinant DNA technology allows production of antigenic polypeptides of pathogens in bacteria or yeast (like hepatitis B vaccine from yeast). The vaccination principle involves introducing antigenic proteins which generate antibodies and memory B and T-cells. Therefore, a 'suitable gene' would be one that codes for such antigenic proteins that can elicit an effective immune response. The answer connects these concepts from the textbook context appropriately for a 2-mark response.
Solution Steps
Step 1: Identify from context that vaccines contain antigenic proteins of pathogens
Step 2: Link this to recombinant DNA technology producing antigenic polypeptides
Step 3: Conclude that 'suitable gene' means a gene coding for antigenic proteins that trigger immune response and memory cell formation