Answer:
The correct answer will be option-C
Explanation:
The CsCl gradient centrifugation in Meselson Stahl experiments is done to separate the bands of the DNA containing isotopes on the basis of difference in the density.
In the experiment, bacterial cultures were grown in the medium of 15N and 14N but if we repeat the experiment with P32 and P31 instead of 15N and 14N and centrifugation is performed then the banding pattern will be the same as of the previous experiment as the method of the replication is same that is semi-conservative.
Thus, Option-C is the correct answer.
<h2>Cell Cycle
</h2>
Explanation:
Eukaryotes grow and divide by cell cycle.
The main parts of a cell cycle are an ordered series of events – Gap 1 or G1 phase, Synthesis or S phase, Gap 2 or G2 phase, and the mitosis or M phases.
Interphase period (G1, S, G2 phases) - cell grows by size, duplicates its content, replicates its DNA, and finally prepares for mitotic cell division
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Mitosis and cytokinesis - formation of two identical daughter cells
Cell cycle is regulated by regulatory or restrictive checkpoints in the cell cycle which are activated with detection of a defective DNA.
Proliferation of undesired or cells with defective DNA like in case of tumor cells is controlled by the action of suppressing agents like p53 and cyclins.
The tumor suppressor gene protein p53 prohibits division of tumor cells. Cyclins regulate cell cycle by activation of the enzyme cyclin-dependent kinase.
The phenotype is the physical appearance of an organism, while the Genotype is the genetic composition of an organism. Phenotype is observable and are the expression of the genes of an individual. So even the organism with the same species may differ, with a minute difference in their genotype. This is the main difference between the two.
We can notice one’s hair colour, eye colour, height, weight, skin colour, etc. but cannot look at genes responsible for these characters, so the observable physical look is the phenotype while the unnoticed genes responsible for such characters present in the DNA of cell of the individual is genotype.
To explain the above lines, here is the simple example of a pure red colour flowering plant (RR) is crossed with the white colour flowering plant (rr). The result of the Genotype of the F1 generation will be – Rr (Hybrid red colour), and the Phenotype of the F1 generation will be the – Red colour flowering plant.
Genotype and phenotype are the two very closely related and similar-sounding words, but their meaning is different. Our earth has a dynamic variety of organisms, present in soil, water and on land. But as the genome of each organism is different, and so there phenotypes also whether it’s their colour, height, weight or other morphological features.
Answer:
Obtain specimen before antibiotics are given.
Explanation:
Antibiotics may be defined as the chemicals given to kill or restrict the growth of the bacterial infection. The antibiotics are not available for virus as they can change their DNA.
The sensitivity results can be accurate if the nurse is able to ensure the successful culture of the antibiotics. Throat culture specimen is taken from the pharyngeal area. The aseptic technique can be used by the nurse for obtaining the blood and urine specimen.
Thus, the answer is obtain specimen before antibiotics are given.
