Hi everyone, I have some simple questions for you. Expound as much as you like, just so long as you know what you are talking about. First of all, how do we really know that DNA is a heritable material? And how do we know how it replicates? I was taught the central dogma of biology, but how did it come to be known? On a tangent note, how do scientists answer questions and how do they come to know things about nature?
Read up on Hershey-Chase's and Griffth's experiments. For replication see Meselson and Stahl. As these are classic experiments I assume that they are described with good accuracy on wikipedia (but should be found in most highschool level textbooks). The central dogma of molecular biology does not deal with either replication nor inheritance per se. It is the accumulation of information transfer from DNA to protein. For the last question: Creating hypotheses and test them.
CharonZ, I appreciate your response. I have taken Principle of Genetics and I understand a little bit (keyword: little) of how DNA replication, transcription and translation works. Excuse me if I sound noobish and ignorant. Would I be wrong in saying that we know DNA is heritable because we can utilize electriphoresis and run gels to analyze the coding strand of DNA then compare similarities in mutations? Can we not just observe chromosomal division in a dividing cell and know that DNA is being replicated? Thanks in advance.
Yes it would be wrong. If you analyze DNA and find changes it is not an argument that it is A) inheritable, and B) that it actually contains information leading to a phenotype. Not to mention that you would not be able to identify point mutations in a simple electrophoresis run. You can only infer mutations after you have established that the DNA is the carrier of inheritable information, not the other way around. If you knew that chromosomes consist of DNA (and proteins) you would know that DNA replicates. But that is not the important bit. The Meselson-Stahl experiment showed how DNA replicates (read up on semi-conservative replication).
