Monoclonal antibodies

• A hormone HCG is found in urine of pregnant women only
• pregnancy test sticks detect this hormone:

The stick you urinate on some antibodies to the hormone with blue beads attached .The test ***** has some more antibodies stuck to it

If you are pregnant:

• the hormone binds to the antibodies .
• the urine moves up the stick, carrying the hormone and the beads
• the beads and the hormone bind to the antibody on the *****
• blue beads which are stuck on the ***** turn it blue

If you are not pregnant:

• the same thing happens but since there is nothing for the blue beads to carry they move to the ***** by themselves
• since there is no hormone to stick the beads onto the *****, it does not go blue