Biotechnology: Applications 2 Flashcards
what are some methods of early diagnosis of disease
for effective treatment of a disease, early diagnosis and
understanding its pathophysiology is very important. Using conventional
methods of diagnosis (serum and urine analysis, etc.) early detection is not possible.
Recombinant DNA technology, Polymerase Chain Reaction (PCR) and Enzyme Linked Immuno-sorbent Assay (ELISA) are some of
the techniques that serve the purpose of early diagnosis.
how can we use PCR to detect disease
Presence of a pathogen (bacteria, viruses, etc.) is normally suspected
only when the pathogen has produced a disease symptom. By this time
the concentration of pathogen is already very high in the body. However,
very low concentration of a bacteria or virus (at a time when the symptoms
of the disease are not yet visible) can be detected by amplification of their
nucleic acid by PCR.
what are the uses of pcr testing
PCR is now routinely used to detect HIV in suspected AIDS patients.
It is being used to detect mutations in genes in suspected cancer patients too.
It is a powerful techqnique to identify many other
genetic disorders.
pcr + probe method for detection of disease
A single stranded DNA or RNA, tagged with a radioactive molecule
(probe) is allowed to hybridise to its complementary DNA in a clone of
cells followed by detection using autoradiography. The clone having the
mutated gene will hence not appear on the photographic film, because
the probe will not have complementarity with the mutated gene.
what is elisa
ELISA is based on the principle of antigen-antibody interaction.
Infection by pathogen can be detected by the presence of antigens
(proteins, glycoproteins, etc.) or by detecting the antibodies synthesised
against the pathogen.
It is the method used to detect AIDS virus.
BIOTECHNOLOGICAL APPLICATIONS IN MEDICINE
The recombinant DNA technological processes have made immense impact
in the area of healthcare by enabling mass production of safe and more
effective therapeutic drugs. Further, the recombinant therapeutics do not
induce unwanted immunological responses as is common in case of
similar products isolated from non-human sources. At present, about
30 recombinant therapeutics have been approved for human-use the
world over. In India, 12 of these are presently being marketed.
for where was insulin extracted earlier?
Management of adult-onset diabetes is possible by taking insulin at regular time intervals.
Insulin used for diabetes was earlier extracted from pancreas of slaughtered cattle and pigs. Insulin from an animal source, though caused
some patients to develop allergy or other types of reactions to the foreign
protein.
describe the structure of insulin? how is the complete structure reached?
Insulin consists of two short polypeptide chains: chain A and chain B, that are linked together by disulphide bridges.
In mammals, including humans, insulin is synthesised as a pro-hormone (like a pro-enzyme, the pro-hormone also needs to be processed before it becomes a fully mature and functional hormone) which contains an extra stretch called the C peptide. This C peptide is not present in the mature insulin and is removed during maturation into insulin.
what is themost difficult step of rthe producing insulin using rdna technology
The main challenge for production of insulin using rDNA techniques was getting insulin assembled into a mature form. In 1983, Eli Lilly an American company prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced them in plasmids of E.coli to produce insulin chains. Chains A and B were produced separately, extracted and combined by creating disulfide bonds to form human insulin.
what is meant by gene therapy
Gene therapy is a collection of methods that allows correction of a
gene defect that has been diagnosed in a child/embryo. Here genes
are inserted into a person’s cells and tissues to treat a disease.
Correction of a genetic defect involves delivery of a normal gene into
the individual or embryo to take over the function of and compensate
for the non-functional gene
first instance of gene therapy? what is the disease ?
The first clinical gene therapy was given in 1990 to a 4-year old girl
with adenosine deaminase (ADA) deficiency. This enzyme is crucial for
the immune system to function. The disorder is caused due to the deletion
of the gene for adenosine deaminase.
what are some temporary cures ofr ada deficiency
In some children ADA deficiency
can be cured by bone marrow transplantation; in others it can be treated
by enzyme replacement therapy, in which functional ADA is given to the
patient by injection. But the problem with both of these approaches that
they are not completely curative.
engineered lymphocytes method
As a first step towards gene therapy,
lymphocytes from the blood of the patient are grown in a culture outside
the body.
A functional ADA cDNA (using a retroviral vector) is then introduced into these lymphocytes, which are subsequently returned to
the patient.
However, as these cells are not immortal, the patient requires
periodic infusion of such genetically engineered lymphocytes.
permanenet cure for ada
However, if
the gene isolate from marrow cells producing ADA is introduced into cells
at early embryonic stages, it could be a permanent cure.
