Cell Division and Protein Synthesis

CHROMOSOMES

Chromosomes are string-like structures located in the cell nucleus of animal and plant. Each chromosome is made of protein and a single molecule of DNA.

Add caption

For an organism to grow and function properly

, cells must constantly divide to produce new cells to replace the old, worn-out cells. During cell division, it is important that the DNA remains intact and evenly between cells. Chromosomes are an important part of the process that ensures accurate DNA is copied and distributed in the majority of cell division. However, errors do occur on rare occasions.

Changes in the number or structure of chromosomes in new cells can cause serious problems. For example, in humans, a type of leukemia and some other cancers caused by a faulty chromosome consists of pieces that join the broken chromosome.

CELL DIVISION

Cell division associated with generative reproduction is one kind, called meiosis. The other type, cell division and cell growth associated with the replacement or repair, called mitosis. In both types of cell division, the nucleus divides and the DNA is replicated.

Mitosis

Before this, the original genetic material of cells (parents) replicated during the S phase of the cell cycle so that when the cell enters mitosis through four major phases that lead to the formation of two identical cells (children):
Stage 1: Prophase: formation of paired chromosomes, the loss of the nuclear membrane, the appearance of the achromatic axis, the formation of polar bodies
Phase 2: Metaphase: the preparation of chromosomes in the equatorial plane. Separate chromosomes into two equal parts exactly.
Stage 3: Anaphase: the two groups of children chromosomes separate and move along fibers of the central spindle, each heading one aster, forming diaster.
Stage 4: Telophase: two core formed, the cytoplasm divides, forming two complete daughter cells.
Initially, mitosis refer only to nuclear division accompanied by cytokinesis (which is a division of the cytoplasm), as in the case of some cells such as certain fungi and the fertilized egg most insects. As used today, is used interchangeably with the mitotic cell division.

Meiosis

Meiosis, on the other hand, reducing the number of chromosomes by half, so that, for example, a human egg and sperm cells, called gametes, each have 23 chromosomes and can combine to produce a zygote has 46. It has two phases division, mitosis whereas only one , Meiosis in animals is called gametogenesis, in particular, spermatogenesis, producing sperm, the male and oogenesis, produce an egg or ovum, in women. In a state is not unified, eggs and sperm are called haploid cells – have only one set of chromosomes, and they become diploid – has a pair of each chromosome – again when they unite during fertilization.

PROTEIN SYNTHESIS

Protein synthesis consists of two main parts – the transcription and translation. This process involves the ribonucleic acid (RNA), deoxyribonucleic acid (DNA) and a set of enzymes. All kinds of ribonucleic acid, the messenger ribonucleic acid (mRNA), ribosomal ribonucleic acid (rRNA) and transfer ribonucleic acid (tRNA) which is required for protein synthesis. See the following information to understand the two parts in the process of protein synthesis.

Transcription
Transcription is the first part in the process of protein synthesis. This happened in the cell nucleus, where the deoxyribonucleic acid (DNA) is housed in the chromosomes. As we all know, DNA is a double helix structure. Of two parallel strands, one acting as a template to produce mRNA. As an initiation step of transcription, RNA polymerase binds itself to a certain site (promoter region) on one strand of DNA that will act as a template.

After attachment to the template strand of DNA, polymerase enzyme synthesizes mRNA polymer under the direction of the template DNA. MRNA strand stretches until the polymerase reaches ‘terminator region’ in the template DNA. Thus, transcription of DNA involves three steps – initiation, elongation and termination. The newly transcribed mRNA is released by the polymerase enzyme, which then migrate to the cytoplasm to complete the process of protein synthesis. Know more about the transcription of DNA.

Translation
The second major part of this process is the translation. Contrary to that transcription occurs in the nucleus, translation takes place in the cytoplasm of the cell. This section starts as soon as the mRNA is transcribed into the cytoplasm. Ribosomes present in the cytoplasm immediately attached to the mRNA at a specific site, called the start codon. Amino acyl tRNA also binds to the mRNA strand. This phase is called initiation.

When the ribosome moves along the mRNA strand, amino acyl tRNA the amino acids one by one. This particular stage is called elongation. In the termination stage, the ribosome reads the last of the strand mRNA codons. With this, the ending part of the translation and the polypeptide chain is released. Precisely speaking, in translation, the ribosome and the tRNA attaches to the mRNA, which reads this information in the chain code. Thus the synthesis of proteins from amino acid sequence of a particular case.

Overall, the process of protein synthesis involves the transcription of DNA to mRNA, which is then translated into proteins. Thus, we have seen the process of protein synthesis requires precise coordination of RNA, DNA, enzymes and ribosomes.