Overview of Genetics - Book Report/Review Example

Overview of Genetics" Genes form the basis of life as they carry plethora of information for the formation of proteins to carry out numerous biological functions. As science go, genetics is young, yet for thousands of years people have sought answers to questions about inheritance. Scientifically sound answers became possible about 150 years ago. In 1865, an obscure Austrian monk, Gregor Johann Mendel reported his discoveries of the fundamental laws of inheritance. He suggested that every cell contained pair of "factors" and each is responsible for specific trait. The members of each pair segregated from each other during the process of sex-cell formation. In 1900, with the description of cell structure and cell division a solid framework appeared and Mendels principles paved the way for the era of genetics and its understanding. The spectacular unfolding of all the modern genetic concepts has taken less than a century. Genetics moved from the obscure units or "factors", now called "genes", segregating and assorting independently of each other in nuclei of cells. Further, the discovery of DNA (deoxyribonucleic acid) was formulated as the chemical basis of heredity. An understanding about genes took a new paradigm from vague understanding of relationship between units of inheritance, the genotype and the physical appearance of the individual called the phenotype. It is deciphered that genes carry coded information in the cells which are responsible for the formation of proteins and hence other macromolecules. Further it was postulated that any alteration in the structure of genes could result in the variation of proteins affecting normal physiology of an individual. Such alterations are called mutations. Mutation can occur in a natural way or induced either by artificial agents or by means of various new techniques called genetic manipulation. Today, molecular technology allows manipulation of genetic material, this has opened entirely new vistas on the fact how genes work, how they are being regulated and how genetic defects can be detected, modified or corrected. Thus genetics is more than a conceptual science; it is a vital and dynamic science that touches all facets of our being. One of the most imperative genetic technology emerged to bring a revolution is Genetic Engineering (GE). GE is a methodology devised to manipulate or modify genes by altering their genetic code, all the way through artificial means generating transgene. The process differs from traditional selective breeding which differs from the natural selection process. GE is emerging as the most rapidly progressing branch of biology and manipulation of genes is becoming a routine act or play. GE works because conservation of genes is observed throughout the evolution. GE encompasses insertion of a particular genetic sequence isolated from any species into some different animal or plant or bacteria and hence monitoring the expression of the genetic sequence. Advances in technology has generated an ease in the manipulation of genetics of the organisms for the better yield, for drugs for hormones such as insulin and alpha-1 antitrypsin etc. This implies that genetic engineering has empowered humans to modify genes and eliminate ailments thereby a new field of genetics emerged called the gene therapy where manipulation of genes is performed to replace the defective gene by a normal one and thereby enabling the individual to get rid of all the worries and problems caused due to defective genes. Genetics thus possesses immense potential to change the identity of the organism. Thus genetics is imperative for every field, to enhance the crop yield, to generate vaccines or other medical products and gradually genetics is finding its way in every aspect of human existence, in the form of genetically engineered food products, genetically engineered fruits, genetically modified vegetables, bakery items, genetically modified animals to yield high quantity of milk and dairy items, genetically modified poultry animals, genetic engineering has now paved its way in cosmetics, wearable, treatment of diseases, manufacturing industrial products that are designed to enhance the production, gene manipulation is engrossing every parameter of human existence which one can think of. Reference Snustad, D. P., Simmons, M. J. "Principles of Genetics". 4th Edition. Publisher John Wiley & Sons Inc. 2005. "Beyond Mendels Laws" According to Mendel’s Law, genes can exist in alternate forms called the allele. Mendel defined two alleles for each character. An allele is dominant if it has the same phenotypic (external appearance) effect in heterozygote as in homozygote, e.g. AA and Aa are phenotypically indistinguishable, while allele with aa is said to be recessive that remains suppressed in the presence of dominant allele. Mendel was lucky as the characters he selected for his studies were not linked. Exceptions to Mendel’s Law of Dominance were perceived in incomplete dominance, Co-dominance, and multiple alleles. Incomplete Dominance: In snapdragon, Antirrhinum majus, the heterozygote has a phenotype different from the either of its homozygotes. Red (RR) and white (rr) varities are homozygous for different alleles of color determining gene, when they are crossed the heterozygotes (Rr) have pink flowers, indicating that allele red (R) is partially or incompletely dominant over the allele for white (r). Differences in phenotype could be due to difference in the amount of product specified by R allele. The genotypic ration thus is 1:2:1 (RR: 2Rr: rr). Co-dominance: in this case alleles produce independent effects when they are heterozygous, indicating that there is an independence of allele function, none of the allele is dominant or partially dominant over the other and therefore they are written as super scripts. E.g. Karl Landsteiner’s blood group. IAIA represents Blood group A, also IA IO also represent blood group A IBIB represents Blood group B, also IB IO also represent blood group B IAIB represents Blood group AB (CO-DOMINANT) IOIO represents Blood group O Thus, when both alleles A and B are present then both are dominant and therefore, they are said to be co-dominant. Multiple Alleles: Genes exist in more than two forms (not in only two forms stated by Mendel). E.g. the coat color of rabbit is controlled by many genes. Genotype cc will have albino phenotype, genotype chch will have black hairs on the extremities and white all over, while cchcch have white and black tips on the body and c+c+ possess coloured hair all over. Most of the wild population is homozygous for the c+ allele; this allele is called wild-type whereas all the other alleles of the c gene are mutants/ altered forms of the wild-type allele that must have arisen during the process of evolution. The himalayan, chinchilla, albino or colourless are all mutant varieties. Polygenic inheritance where two or more genes are required for the expression of a character or a phenotype such as colour of the skin is controlled by many genes. Other features that cannot be explained using Mendels Laws also involve albinism, sex- linkage and sex-linked inheritance, Turners Syndrome, Baldness in males, the method by which dominance of a gene works, polydactyly etc. Reference Snustad, D. P., Simmons, M. J. "Principles of Genetics". 4th Edition. Publisher John Wiley & Sons Inc. 2005. Read More