RNA is said to be as the first genetic material because
1. RNA can directly code for protein synthesis of protein and hence can easily expresses the character. It is the genetic material in many viruses.
2. RNA can also act as a catalyst; there are some important biothemical reactions in living systems that are catalyzed, by RNAs and not as proteins.
3. Many essential life processes like splicing translation, etc have evolved around RNA.

In the complete absence of lac operon permease will not be synthesized which is essential for transport of lactose from the medium into the cells, then it cannot act as an inducer. Hence, cannot relieve the lac operon from its repressed state.

When lactose is absent "i" gene regulates and produces repressor mRNA in the absence of lactose, which blocks the transcription. The repressor protein binds to the operator region of the operon and as a result prevents RNA polymerase from binding to the operon. The operon will be switched off (stop) in this situation.

(i) Identify all the genes (approximately 30000) in human DNA.
(ii) To store this information in databases.
(iii) Improve tools for data analysis.  

During DNA replication, One acts as the leading strand and the other is the lagging strand.