Quiz 9: Molecular Structure of Dna and Rna
Genetic material is a substance that is an integral part of a cell and has the properties of storing information, capacity for the transmission of the stored information, the ability to replicate itself, and that can induce variations in life forms. • The genetic material is the biologically active molecule that should store information regarding all life processes and the components (such as proteins) that go into the biological processes. • The genetic material should have the capacity to be transmitted to subsequent progeny, at both the cellular level (cell division) or at the organism (reproduction) levels. • The genetic material should have the ability to replicate itself; to produces copies of itself, as required for transmission. • The genetic material should have the property to induce changes in its expression, thus bringing about variations within and among life forms.
The genetic material should have the capacity to store information, an ability to self-replicate, should be transferable to the offspring (cells or entire organisms) and should ace the property to induce variations or changes in life forms. The two type of genetic material are the DNA and the RNA. The genetic material of an organism contains all the information regarding the life form (including the physiological functions and the other phenotypic traits), thus acting as a blueprint of the organism's traits. One of the first experimental evidence for the presence of a genetic material and its ability to be transferred was demonstrated by Frederick Griffith in 1928. He demonstrated this by explaining the transformation process in the pneumonia causing bacteria, Streptococcus pneumoniae. In his experiment Griffith demonstrated that in the presence of type S virulent bacterial strain, the type R non-virulent strain gets transformed into a virulent strain. The experiment also concluded that the 'transformation factor' that could induce a new trait in the R type bacteria is the genetic material as it controlled the phenotypic trait as required for virulence. Key points of the Griffith's experiment are as follows: • Type S bacteria was the virulent strain and caused the disease in a host mousE.• Type R bacteria was the non-virulent strain and did not cause the disease in a host mousE.• Heat-killed type S bacteria lost virulence and did not cause the disease in a host mousE.• Type R bacteria, the non-virulent strain caused the disease in a host mouse when presented along with the heat-killed S strain. Thus, the genetic material ('transforming principle' which is the DNA) from the heat killed S strain transformed the normally non-virulent type R strain into a virulent form.
The genetic material should have the capacity to store information, the ability to transmit information, the ability to replicate itself to make multiple copies and finally to have the capacity to induce variations or changes in life forms. One structure other than the DNA double helix that can potentially be the genetic material is the single stranded RNA. Such a structure can have all the capacities that the DNA has, as listed abovE.One more structure that is different to that of the double helix is a two layered circle, as similar to the plasma membrane of the cells.