Lec(4)Transmission of genetic material.pdf

Transmission of genetic material Lec. (4) Dr. Laila E. Taha  Genetic transmission is the mechanism that drives evolution. DNA encodes all the information necessary to make an organism. Every organism's DNA is made of the same basic parts, arranged in di...

Transmission of genetic material Lec. (4) Dr. Laila E. Taha  Genetic transmission is the mechanism that drives evolution. DNA encodes all the information necessary to make an organism. Every organism's DNA is made of the same basic parts, arranged in different orders. DNA is divided into chromosomes, or groups of genes, which code for proteins.  RNA and DNA were thought as genetic material. But many experiments suggest DNA as genetic material rather than protein and RNA  The genetic material of a cell or an organism refers to those materials found in the nucleus, mitochondria and cytoplasm, which play a fundamental role in determining the structure and nature of cell substances, and capable of self- propagating and variation.  DNA Must carry information Cracking the genetic code Must self replicate ( DNA replication) Must allow for information to change Mutation Must govern the expression of the phenotype Gene function  DNA is metabolically stable, meaning that it is not rapidly degraded like many other cellular molecules. Furthermore, the amount of DNA per cell in a given species of higher organism remains fairly constant, unaffected by changes in the environment or nutrition. There is a direct correlation between the absorption of ultraviolet light by DNA and the rate of mutation. The rate of mutation is highest at the wavelength of maximum absorption, suggesting that DNA is the hereditary material and when irradiated undergoes chemical changes which cause mutations.. DNA is capable of accurate replication. This mechanism ensures the faithful copying of the genetic information at each cell division, thus genetic information can be passed unchanged from one generation to the next. DNA codes for all the instructions for making proteins, the macromolecules needed for the cell to perform different functions.  The Structure and Function of Genes The complete set of instructions for making an organism is called its genome. It contains the master blueprint for all cellular structures and activities for the lifetime of the cell or organism.  The genome consists of tightly coiled threads of deoxyribonucleic acid (DNA) and associated protein molecules, organized into structures called chromosomes. For each organism, the components of these slender threads encode all the information necessary for building and maintaining life, from simple bacteria to remarkably complex human beings.  Genetic disorders Example Sickle cell anemia is one of a group of disorders.  Sickle Cell Anemia Due to presence of recessive allele denoted by HbS. Causes distortion of red blood cells into long, thin sickles. Causes pain, tissue damage, and cells to rupture prematurely. Carriers: have heterozygous genotypes and do not manifest symptoms. Thank You & Good Luck