Nursing Entrance Exam

Chromosomes are essential in the process of cell division. In mitosis cell division, the chromosomes have to be replicated and then divided between the two resulting daughter cells. This ensures that the resulting two daughter cells are genetically identical to the original mother cell. DNA DNA, or deoxyribonucleic acid, is an essential component of life. It is often described as the blueprint of a living organism, as it contains vital genetic information and instructions that are required for the proper functioning and development of all types and forms of living organisms and viruses. The three most important macromolecules essential for any life form are DNA, proteins, and RNA. The genetic information contained in the DNA is encoded as a sequence of nucleotides known as G, A, T, and C – G as guanine, A as adenine, T as thymine, and C as cytosine. These nucleotides are arranged as DNA molecules in a double-stranded helix. The strands run in opposite directions; thus, they are anti-parallel. The DNA contains long structures known as chromosomes. RNA RNA, or ribonucleic acids, are large biological molecules that perform the important roles of decoding, coding, regulating and expressing the genes and the information contained within them. The RNA is also composed of nucleotides, but unlike the DNA that is double-stranded, the RNA is single-stranded. In organisms, some RNA components serve as messengers to convey genetic information to direct the synthesis or use of certain proteins for specific purposes. It can be said that RNA is essential for the proper carrying out of the information contained in the DNA genes. RNA plays important roles within the cell, such as helping to catalyze biological reactions, sense and communicate cellular signals, and control gene expressions. RNA is also essential for protein synthesis. Mitosis and Meiosis Meiosis and mitosis are two types of cellular division and they are involved in cell reproduction and the maintenance of tissues. The cell is the basic functional unit of living organisms, and it is comprised of a collection of organelles and other cell matter dispersed within the cell membrane. For new cells to form, existing cells divide through the process of meiosis or mitosis depending on the type of cell and reason fordivision. Mitosis refers to the division of a cell into two identical cells. The original cell goes through a process of duplication of its genetic material and then equally divides its contents into two new daughter cells. The process of mitosis goes through several stages until the two cells separate to form two distinct, yet genetically identical cells.

Achieve

Page 152

of 175

© 2018