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. Watson and Crick
C. Hamilton O. Smith, Kent W. Wilcox, and Thomas J. Kelly
D. Paul Berg
Answer: Option C
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:
Bacteria are prokaryotes with a single circular chromosome in a nucleoid region, without a nuclear membrane. They lack membrane-bound organelles like mitochondria. Their chromosomes are not linear; eukaryotes have linear chromosomes.
Explanation:
Osmosis is the special case of diffusion of water across a semipermeable membrane down its concentration gradient (from high to low water potential). It does not require energy. Diffusion refers to solute movement, active transport requires energy against a gradient, and plasmolysis is the shrinking of protoplasm due to water loss.
Consider statements about microorganisms: 1. Penicillin is extracted from a fungus. 2. Streptomycin is extracted from a bacterium. 3. Viruses can be cultured in synthetic media. Which are correct?
Explanation:
Penicillin, the first antibiotic, is extracted from the fungus Penicillium notatum. Streptomycin is an antibiotic derived from the actinomycete bacterium Streptomyces griseus. Viruses are obligate intracellular parasites and cannot be grown or cultured on artificial synthetic media; they require living host cells (like embryonated eggs or cell cultures) to replicate. Thus, statements 1 and 2 are correct.
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