Hello!! The answer would be A - The SA node. It is known as the "pacemaker" because it initiates the heart's rhythmic contractions. I hope I helped!! Have a great day. :)
One advantage of genetic engineering is the production of valuable proteins: recombinant DNA made possible the use of bacteria to produce proteins of medical importance such as genetically engineered human insulin which is of great importance.
Another advantage is the production of vaccines. Vaccines produced by genetic engineering offer an advantage that the microbial strains from which proteins are extracted do not contain complete viruses and thus there is no risk of accidental inoculation with live virus.
Answer:
Explanation:
During mitosis, the chromosomes are distributed equally in the resulting chromosome. The chromosome number was doubled in the S phase of the interphase and the cell is ready for mitosis. The chromosomes are more condensed and twisted in prophase. It is also double in length. During the metaphase, the chromosomes are arranged in the metaphase plate. The microtubules from the centriole attach to the centromere of each chromosome and pull them towards the pole.
Thus each chromatid pulls apart and migrates towards the poles. The nuclear membrane and nucleus disappear during mitosis. At the end of telophase, the daughter cells contain an equal number of chromatids as in the parent cell.
Sometimes the microtubules of centrioles do not function properly and fail to pull the chromosomes equally to the cells. Thus one of the daughter cells contains more chromosomes and another fewer chromosomes. This occurs in anaphase. This results in the non-disjunction of chromosomes.
Sometimes centromere splits transversely instead of longitudinal division. This results in the formation of 2 daughter chromosomes of unequal length. This is called the isochromosomes.
The number of chromosomes distributed in the daughter cells results in a normal cell or any genetic disorder. The main function of mitosis to produce daughter cells having an equal number of chromosomes present in the parent cell.
