chempath tut4

1. Multiple choice: Choose the correct answer.

1.1 Characteristic X-rays are emitted during the nuclear reaction involving:
a. gamma decay
b. electron capture
c. positron decay
d. negatron decay
e. none of the above

1.2 In quantitative immunoassays the single most important factor responsible
for success or failure is:
a. affinity
b. titer
c. monoclonal property
d. antibody absorption
e. specificity

1.3 Which of the following compounds are often monitored by competitive
binding assays?
a. therapeutic drugs
b. protein hormones
c. estrogens
d. antibiotics
e. all of the above

1.4 Elevated T4 and T3 uptake together suggest the likelihood of :
a. hyperthyroidism
b. decreased TBG
c. hypothyroidism
d. decreased TSB
e. None of the above

1.5 TRH is secreted by the :
a. anterior pituitary
b. posterior pituitary
c. adrenal cortex
d. thyroid gland
e. hypothalamus

1.6 Steroid hormones are transported in blood :

a. Covalently bound to protein
b. Are free hormones
c. Non- covalently bound to specific proteins
d. In red blood cells
e. None of the above.

1.7 Which of the following describes the chemical characteristic of an antibody?

a. Carbohydrate
b. protein
c. lipid
d. electrolyte
e. ligand

1.8 Immunonephelometry is based upon the principle that :

a. antigen and antibody form small complexes in antibody excess
b. antigen and antibody form complexes in antigen excess
c. antigen and antibody react to form precipitin line
d. antigen and antibody form large complexes which precipitate
e. antigen and antibody form large lattice structures, which precipitate.

1.9 In double diffusion, immune precipitation reactions occur when two lines cross
each other: the reaction is one of:

a. antigen identity
b. identity
c. partial identity
d. non – identity
e. antibody identity

1.10 Which of the following factors affects antigenicity?

a. chemical nature
b. size
c. conformation
d. genetics
e. all are correct
[10]

2. Write an essay on the steps involved in the practical performance of RIA.
[12]

3. State whether the following statements are true or false. If false give an
explanation.


3.1 Steroid hormones are covalently bound to specific proteins and transported in blood.

3.2 When an antigen and antibody form small complexes in antigen excess, it is based on the principle of immunonephelometry.

3.3 Polyclonal antibodies are predominantly of the IgM type.

3.4 The posterior pituitary is also known as neurohypophysis
[6]


4. Certain requirements must be met for an enzyme to be suitable for EIA.
Discuss. [6]


5. Explain how immunonephelometry can be used to measure IgM. [6]

6. Explain what you would do if placed in the following situation:

Thembi is a patient whose blood sample was taken in the Endocrine clinic a month ago. She apparently phoned the clinic but was closed. Thus she called the laboratory for the result. You happen to answer the phone. You take her details and from the computer there was a TSH result of > 100 umol/l.
[2]


7. Draw a typical RIA graph for which a test like cortisol is plotted. [2]


8. Write short notes on waste disposal of radioactive material. [7]


9. What would the final dilution of serum be if 0.2ml was added to 39.8 ml of distilled water and then 1 ml of this was added to 7 mls of a reagent solution? [5]

10. Explain how you would prepare 40 ml of each of the following standards using a stock solution on 40g/l:
10.1 10 g/l
10.2 4 g/l [4]