The Genetics

rChromosomes constitute DNA along with proteins called histones (Youngson, 2006). A gene is located on the DNA at a place called as locus. The genes that are present on the DNA of the chromosome inherited from brother will be  similar to that of the same gene which has been contributed by sister. There might be some cases when there will be variation in the gene contributed from parent. These differences in genes will generate different alleles of the same gene. allele from parent and other from another parent will be involved in looking after the trait ruled by that gene.

Human genetics and genetics in general is a fascinating field of science. Over 80 percent of the scholars who like to concentrate on this field would have completed that out of passion for the subject. Each and every characteristic feature in our body which is called as "trait" in scientific terms is ruled by genes. Even the mental strength and talent in us are also found to be influenced by the genes to some extent. Some of the inherited traits like color of the hair or ear shape might have no effect on our life. But, the disorders like hemophilia, color blindness and so on might show negative impact on the quality of our life. Human beings have cells that have nucleus harboring chromosomes. There's 22 pairs of autosomal chromosomes and two sex chromosomes in human cells. humans will have 46 chromosomes in a diploid cell. In the case of gametes, egg will have 23 chromosomes and sperm will possess 23 chromosomes.

The functional genetic knowledge is present in the DNA in the kind of genes. The useful knowledge in the DNA will be transcribed in to hnRNA or hetero nuclear RNA by a method called transcription. Actually, hnRNA is an intermediate product of transcription. It consists of Exons and Introns. Introns are regions which do not possess functional significance. Introns only provide structural integrity to the DNA. Exons will possess functional code that will further get transformed in to mRNA or messenger RNA in the transcription method. The transcription is carried out in the nucleus of the cell in the presence of definite enzymes. The mRNA that is created in the nucleus moves to the cytoplasm.

The mRNA assembles the Ribosomes on it and chain up the amino acids to form a polypeptide chain. The formation of proteins from the mRNA is called translation and this method also involves several enzymes. The proteins may work as hormones or participate in any part of the metabolic reactions. A defective gene will produce a defective protein. If of the alleles is flawed and the other allele can give rise to protein to carryover out the function, then the disease that would have resulted from the defective allele won't occur. The recessive gene that was inherited did not produce disease. If allele is to produce a disease then the allele is said to be dominant and the disease is result of dominant gene. If there is any alter in any of the alleles which is causing the disease, then the gene is heterozygous for the disease. If the disease resulted from both the recessive genes inherited from the parents, then the gene is homozygous for the disease. Diseases occur based on genetic disorders, chromosomal disorders, mitochondrial DNA linked disorders.


References
1. Youngson, Robert M. (2006). Collins Dictionary of Human Biology. Glasgow: Harpercollins