Imagine it is the early 1900s and the nature of genetic material is not yet know
ID: 212645 • Letter: I
Question
Imagine it is the early 1900s and the nature of genetic material is not yet known. You believe that protein is the most likely candidate for holding information, rather than DNA (which you regard to be some form of “nuclear excrement”).
a) Make an argument supporting this position (purely from a theoretical standpoint, of course!).
b) Explain how either [Avery, MacLeod, and McCarty] or [Hershey and Chase] contributed to our understanding of DNA as the genetic material.
c) How did Rosalind Franklin contribute to Watson and Crick’s elucidation of the structure of DNA?
d) What are Chargaff’s rules, and how did Chargaff’s Rules contribute to Watson and Crick’s elucidation of the structure of DNA?
Explanation / Answer
Ans-A in that time there was no experimental evidence which may provide information about the genetic material so protein was considered as genetic material. The function and non function of the cells is dependent on the protein which are made by transcription and translation, but in olden times only protein was known so their presence or absence was thought to be the reason.
Ans-B- Avery,MacLeod and Mc Carty perform an experiment in which they mix the heat killed rough strain (infectious) of bacteria with alive smooth strain bacteria(non infectious). It causes infection in the mice. It provide evidence for tramsformation.
Harsey and Chase perform experiment where they label the DNA of bacteriophage with phosphorus and their protein coat with sulphur. Both were introduced into different bacteria. In the next step the DNA was replicated in host cell which provide evidence in favour of DNA .
Ans-C Franklin was a X-ray chromatographer . He took xRay chromatogram of the dry and wet DNA and concluded that it was helicel structure which was close enough to Watson and crick modal.
Ans-D he conclude two rules 1) the no of adenine is equal to thaimine and no of cytosine is equal to guanine.
#) the amount of four bases may vary in different species which help in concluding that DNA may be the genetic material.