In mature insulin,chain $A$ and chain $B$ are interlinked by which bond?

Identify the correct statement.

$ELISA$ technique is based on the principles of antigen-antibody interaction. Can this technique be used in the molecular diagnosis of a genetic disorder,such as phenylketonuria?

Match List-$I$ with List-$II$:

List-$I$	List-$II$
$A$. Genetically engineered Human Insulin	$I$. Gene therapy
$B$. $\text{GM}$ Cotton	$II$. $\text{E. coli}$
$C$. $\text{ADA}$ Deficiency	$III$. Antigen-antibody interaction
$D$. $\text{ELISA}$	$IV$. $\text{Bacillus thuringiensis}$

Choose the correct answer from the options given below:

In which year did the company Eli Lilly prepare two $DNA$ sequences corresponding to $A$ and $B$ chains of human insulin?

Which of the following is/are correct about Adenosine Deaminase $(ADA)$ deficiency?
$I$. In the absence of adenosine deaminase enzyme,purine metabolism is disturbed and $T$-lymphocytes fail to function.
$II$. $ADA$ deficiency is caused by the deletion of the gene for $ADA$.
$III$. In some cases,it can be cured by bone marrow transplantation and enzyme replacement therapy. But in both approaches,the patients are not completely cured.
$IV$. For permanent cure,genes isolated from the bone marrow cells producing $ADA$ at early embryonic stages can be a possible cure.
Which of the above statements are correct?