Steps for semester 1 exam

Question 1

Name the steps of recombinant DNA technology

Answer 1

• commonly, insulin is produced through E.Coli bacterium
  1) Isolate human gene responsible for investigated hormone and decide to put human DNA into plasmid of bacteria
  2) Get bacterial DNA out of bacteria, called plasmid extraction
  3) Cut human DNA and bacterial DNA with same restriction enzyme
  4) Mix cut human DNA(has investigated gene) with cut bacterial DNA, and add DNA ligase to stick them together
  5) Get recombinant plasmid back into bacteria, called transformation
  6) Bacteria will then multiply and produce investigated hormone(eg. insulin)

Question 2

Steps for inflammatory response

Answer 2

1) Mast cells release chemicals histamine and heparin into tissue fluid
2) Histamine increases blood flow through area and increases permeability of capillary walls so that fluid is filtered from the blood
3) Heparin prevents clotting in immediate area, however, a fluid clot does form to protect healthy tissues(slows spread of pathogens)
4) These chemicals attract phagocytes
5) Pain receptors pick up pain
6) Pus forms from dead phagocytes and tissue fluid
7) New cells are produced via mitosis and repairs tissue damage

Question 3

Steps of antibody-mediated immunity

Answer 3

1) If an antigen penetrates non-specific defences, it can be directly identified by a specific B cell in the lymphoid tissue
2) This particular B cell is sensitised and enlarges, dividing to form clones
3) Most of the clones become plasma cells
4) Plasma cells manufacture proteins(antibodies) that can target the antigen
5) Antibodies travel through bloodstream throughout the body to seek out antigen
6) Once the antibodies locate the antigen, they attach to its surface and inactivate it(antigen-antibody complex)
7) Antibody helps destroy antigen by agglutination, making it insoluble and punching holes

Question 4

Steps of cell-mediated immunity

Answer 4

1) If any foreign material penetrates the external defence, it is directly identified as non-self by macrophages
2) Macrophage engulfs non-self and breaks it down using enzymes within lysosomes
3) Parts of materials surface(antigen) is displayed on the outside of macrophage membrane
4) Macrophage travels through lymphatic system until it encounters a T-helper cell that identifies the specific antigen
5) T-helper responds by enlarging and forming clones
6) T-helper cells release cytokines to activate both killer t-cells and b-cells
7) Activated killer t-cells then ‘search and destroy’ infected cells