15.7 Urine And Diagnosis

Question 1

Describe and explain how pregnancy tests work

Answer 1

• a stick with an application area that contains monoclonal antibodies for hCG bound to a coloured bead
• when urine applied to application area hCG will bind to the antibodies that are attached to the pigment
• urine moves up test strip, carrying pigment with it
• antibodies are immobilised and will be arranged in a line or a positive sign to indicate positive test
  If woman is pregnant two coloured lines appear, if not only one appears
• hCG has a molecular mass less than 69,000 this allows it to be detected in urine

Question 2

Describe what monoclonal antibodies are

Answer 2

Antibodies from a single clone of cells that are produced to target particular cells in the body
A mouse is injected with hCG so it makes the appropriate antibody. The B-cells that make the required antibody are then removed from spleen of the mouse and fused with a myeloma, a type of cancer cell which divides rapidly. This new fused cell is known as a hybridoma.
Each hybridoma reproduces rapidly, resulting in a clone of millions of cells producing the desired antibodies

Question 3

Describe urine and anabolic steroids

Answer 3

Anabolic steroids mimic the action of testosterone, stimulate growth of muscles
They’re excreted in urine
It is tested for using gas chromatography and mass spectrometry

Question 4

Urine and drug testing

Answer 4

Tested for using test strips
Positive result linked to colour change