unit 5 - RIA and ELISA

Question 1

what is RIA

Answer 1

a technique for determining antibody levels by introducing an antigen labelled with a radioisotope and measuring the subsequent radio activity of the antibody component

Question 2

what does RIA stand for

Answer 2

Radio Immunosorbent Assay

Question 3

what is RIA used for

Answer 3

• drug tests
• hepatitis detection
• early cancer detection
• growth hormone levels
• proteins
  *detects changes in cells

Question 4

how can RIA detect changes in cells

Answer 4

changes in protein levels by detecting the volume of antigens.

Question 5

how does RIA begin

Answer 5

-take a known quantity of antigen and make it radioactive
- mix it with a known quantity of antibody
- antigen will bind with antibody

Question 6

what is the second phase of RIA

Answer 6

• take a sample from the patient
• the patients unlabelled antigen will compete with the radioactive antigen
• the unlabelled antigen and antibody binds
• the higher concentration of unlabelled patient antigen displaces more radioactive antigen
• we can measure how much labelled antigen has been outcompeted

Question 7

what is the third phase of RIA

Answer 7

• the bound antigens are separated from radioactive unbound antigens
• the radioactivity of bound antigens is measured
• the concentration of unlabelled antigen found by calibration curve
• decrease in activity
• the activity will be proportional to the concentration of the substance being tested for.

Question 8

what does does ELISA stand for

Answer 8

enzyme linked immunosorbent assay

Question 9

phase 1 of ELISA

Answer 9

1. antigens from a sample are attached to a surface ( usually a multi well plate)
2. time is given for the antigen to adhere
3. a buffer solution of a non reactive protein is added to the plate to block any unbound sites to prevent a non specific binding of the antibody.

Question 10

phase 2 of ELISA

Answer 10

4. a specific antibody is applied to the surface so that it can bind with the antigen
5. the antibody is linked to an enzyme
6. any unbound antibodies are washed off

Question 11

phase 3 of ELISA

Answer 11

7. a substance containing the enzymes substrate is added
8. the subsequent reaction produces a detectable signal; colour change
9. the higher the concentration of antibody, the stronger the colour change.

Question 12

what is ELISA

Answer 12

a technique used to detect a presence or absence of a substance