Biology Blogs For Class11th, 12th and NEET

                               Watson and Crick Model of DNA      In 1953 Watson and Crick devised DNA model . DNA is the genetic material found in all living organisms like plants , animals , prokaryote and many virus . In eukaryotes DNA is found in the form of chromosome inside the nucleus but in mitochondria ,plastid and prokaroytes have circular DNA . According to Watson and Crick DNA consist of two polynucleotide chain or strands . These strands are always anti parallel . In each polynucleotide chain the phosphate molecule lie on the outer side of the deoxyribose sugar & nitrogen base inward . The nitrogen bases of the two strands are linked together with the help of hydrogen bonds. In DNA molecule base pairing is very specific . Purine always pair with pyrimidine (A=T) . In the DNA molecule the two strands are twisted around each other and form a double helix around a common central axis . One turn of the helix measures  about 34 A and contains 10 base paired

                              Reproduction in Living Organisms   There are wide range  of living organisms present on the earth . Every individual have different morphology , structure but the process of continuation of the species is the same .  Did you guess what is the process for continuation of species -  it is the  Reproduction , a very important process of for living organisms living on the earth  in which an organisms give rise to offspring which is similar to itself . The offspring again follow the same cycle of their parent i.e that is they grow ,  mature and reproduce and in this way there is a cycle of birth , growth and death . Method of Reproduction -  Reproduction enable the continuity of the species , generation after generation .  There are basically two type of reproduction used by the living organisms . The Asexual Reproduction  which involve involvement of single parent and Sexual Reproduction where the two cell of the opposite sex participate for the for