Deoxyribose Nucleic Acid or DNA
DNA is a molecule found in the nucleus of a cell. It serves as a building block of organisms and contains genes. DNA duplicates itself continuously whenever new cells are formed when genetic material is inherited from parents to offsprings, and to code for RNA to produce proteins.
DNA is a double helix structure and is successfully copied multiple times with only a few errors. DNA is made up of nucleotides containing base, sugar and phosphate. It consists of four bases possessing different chemical structures – where guanine always pairs with cytosine and adenine always pairs with thymine. DNA unzips while replication and is aided by the action of enzymes to initiate and mediate chemical reactions.
Mutations arise while there is an error while copying DNA, some of which are beneficial while some others are not. These mutations are passed on to the next generation if they occur in sex cells. Gamete mutations lead to microevolution. The existence of these random mutations is necessary for the evolution process. Population with beneficial mutations are likely to survive and reproduce passing mutations while those with detrimental mutations are less likely to survive and reproduce. Gregor Mendel was the first one to observe genes and proposed the theory of inheritance. He suggested certain important principles or laws:
- Law of dominance
- Law of segregation
- Law of independent assortment
Traits are inherited from parents. This natural occurrence of different alleles generates variations within a population. To illustrate the type of inheritance, a Punnett square model can be used. Genes provide biological information about our being which cannot be altered once we inherit them from our parents.
Apart from genes, the environment also plays a role in determining human personality characteristics, genetic disorders and physical traits. Furthermore, the effects of epigenetics may lead genes to switch on or off, upregulate or downregulate. The way a trait is produced can be changed through modification in the expression of a gene which not necessarily includes changing the DNA sequence of the gene.
A careful examination of the phylogenetic tree of life reveals if species are closely related, the more closely their DNA sequences will intersect. Species that are distantly related have some degree of overlapping of DNA. To know more about DNA and its association with evolution, please register at BYJU’S.
|Difference Between Gene and DNA|
|Mutation – A Genetic Change|
|Mendel’s Laws of Inheritance|