15.7 Urine and diagnosis

Question 1

Why is urine well suited for diagnostic tests

Answer 1

Contains EXCRETED METABOLITES in high concentrations
Which are non invasive

Question 2

What is immunoassay

Answer 2

Tests which detect for aqueous molecules

using their properties as antigens/antibodies

Question 3

Outline the process of pregnancy tests

Answer 3

1.Wick soaked in urine
◦ Test contains mobile antibodies: complementary to + can bind to hCG

2.hCG in urine BINDS to MOBILE ANTIBODY ⟶ hCG/ANTIBODY COMPLEX
◦ carried along to 1st window, where immobilised antibodies present.

3.hCG/antibody COMPLEX BINDS to IMMOBILISED ANTIBODY, releasing dye.
◦ arranged in pattern, indicating positive test.
◦ urine solution carried to 2nd window.

4.EXCESS MOBILISED antibodies (from stick) BIND to IMMOBILISED antibodies, releasing dye, indicating VALID test.

Question 4

What hormone is present specifically in the urine of pregnant women, and where is it secreted?

Answer 4

hCG, human chorionic gonadotrophin

secreted by placenta into bloodstream after embryo implantation.

Therefore found in urine after ultrafiltration in the Bowman’s capsule.

Question 5

When testing for drugs using urine, why may the urine sample be split into 2?

Answer 5

It allows for repeat testing using different methods for confirmation

Question 6

How is gas chromatography used to detect anabolic steroids in the urine

Answer 6

1.Urine sample VAPORISED + passed along tube with solvent

2.Lining of tube ABSORBS gases

3.Gases analysed, forming chromatogram

Question 7

How are monoclonal antibodies produced

Answer 7

1.Mouse is injected with hCG
◦ Triggers B-cells to produce appropriate antibody
B-CELLS removed + fused with MYELOMA (cancer) cells.
◦ Produces HYBRIDOMA: rapidly divides + produced specific antibody.
Antibodies (which are all of 1 type) PURIFIED + collected

Question 8

What are monoclonal antibodies

Answer 8

Antibodies produced from a clone of cells made to target specific cells/chemicals in the body