Gradual changes in the frequency of diseases over long periods are known as SECULAR TIME TRENDS. For example, the rate of mortality in USA due to coronary heart diseases over a period of time. Onset of puberty in girls is also a secular time trend.
Secular time trend is also referred as Secular Variation and Secular Drift.
The vector, which is often a small, circular piece of dna that can exist outside the bacterial chromosome, is known as a plasmid.
Bacteria and certain other microscopic species contain plasmids, which are tiny circular DNA molecules. Physically distinct from chromosomal DNA, plasmids multiply on their own. They normally contain only a few genes, including some linked to antibiotic resistance, and they can spread from one cell to another.
Recombinant DNA techniques are used by scientists to splice the genes they want to research into a plasmid. The inserted gene is duplicated along with the plasmid when it duplicates itself. Molecular cloning, the process of creating DNA molecules and introducing them into a host cell, uses plasmid vectors as the means of delivering recombinant DNA into the host cell.
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Answer:
DNA:
Dexoyribonucleic acid is the genetic material of almost all the organisms except some virus. DNA contains deoxyribose sugar that lacks 2'OH group on second carbon. The nitrogenous base pair of DNA are adenine, guanine, thymine and cytosine. DNA cannot acts as an enzyme.
RNA:
Ribonucleic acid is present as genetic material in few viruses only. RNA contains oxyribose sugar that has 2'OH group at second position. The nitrogenous base pair of RNA are adenine, guanine, uracil and cytosine. RNA can acts as any enzyme in biological reactions.