The discovery of the enzyme 'restriction endonuclease' was a milestone in biotechnology. The first such enzyme was isolated by: MCQ with Answer and Explanation
The discovery of the enzyme 'restriction endonuclease' was a milestone in biotechnology. The first such enzyme was isolated by:
A. Kary Mullis
B. Paul Berg
C. Watson and Crick
D. Hamilton O. Smith, Kent W. Wilcox, and Thomas J. Kelly
Answer: Option D
Solution (By JKSSB Mock Tests)
While restriction enzymes were first observed by Linn and Arber, the first Type II restriction endonuclease (HindII), which is the type used in genetic engineering because it cuts at specific recognition sites, was isolated and characterized by Hamilton O. Smith, Kent W. Wilcox, and Thomas J. Kelly in 1970 from Haemophilus influenzae. For this discovery, Smith shared the Nobel Prize in Physiology or Medicine in 1978. Kary Mullis invented PCR.
Explanation:
Diapedesis (extravasation) is the migration of leukocytes through the endothelial junctions of capillaries into tissues in response to inflammation. Chemotaxis is the directed movement along a chemical gradient, phagocytosis is ingestion, opsonization is coating for phagocytosis. Both diapedesis and chemotaxis are part of the inflammatory response.
Explanation:
Intervertebral discs are fibrocartilaginous joints (symphyses) that allow slight movement and absorb shock. Hinge joints are in knee/elbow, ball-and-socket in hip/shoulder, sutures are immovable fibrous joints in skull.
Explanation:
Trypsinogen is an inactive proenzyme secreted by the pancreatic acinar cells. Upon entering the small intestine (duodenum), it is specifically activated into the active enzyme trypsin by the enzyme enterokinase (also known as enteropeptidase), which is secreted by the intestinal mucosa. Trypsin then activates other pancreatic proenzymes like chymotrypsinogen and procarboxypeptidase. Pepsinogen is activated by HCl.
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