The technique of polymerase chain reaction (PCR) is used to:
A. Amplify a specific DNA sequence
B. Sequence DNA
C. Cut DNA at specific sites
D. Separate DNA fragments by size
Answer: Option A
Solution (By JKSSB Mock Tests)
PCR is an in vitro technique to exponentially amplify a specific DNA segment using primers, Taq polymerase, and thermal cycles. Electrophoresis separates DNA, sequencing determines base order, restriction enzymes cut DNA.
Explanation:
Alexander Fleming, a Scottish bacteriologist, discovered penicillin in 1928. He returned from a vacation to find that a Petri dish containing Staphylococcus bacteria had been accidentally contaminated by a mold. He noticed a clear zone around the mold where the bacteria had been killed. The mold was identified as Penicillium notatum, and the antibacterial substance was named penicillin.
Explanation:
Cataract is clouding of the crystalline lens, causing blurred vision and eventual blindness if untreated. It is often age-related or due to UV exposure. Myopia is nearsightedness, glaucoma optic nerve damage, astigmatism irregular curvature. Cataract is treated by surgical removal and lens replacement.
Explanation:
Mitochondria release cytochrome c and other factors that activate caspases, initiating apoptosis. They have circular DNA and 70S ribosomes.
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