D What is the colinear relationship between DNA RNA and prot

D. What is the colinear relationship between DNA, RNA and protein? How does it relate to the structures of typical prokaryotic and mammalian genes?

Solution

The colinear relationship between DNA, RNA and protein is DNA is changed into RNA by the process of transcription, RNA is translated into amino acids of proteins by the process of translation. These proteins eith the help of its different functions help in the formation of an organism.

The genes in the prokaryotes are usually arranged in the form of an operon with the functional genes clustered together and all tgese genes operates from a single promoter. Transcription produced a continuous strand of RNA. Thus prokaryotic genes have very few non coding sequences. Thus DNA is transcribed into a colinear RNA which by translation is changed into proteins. Usually these clustered gened contribute to a single metabolic function.

In eukaryotes like also in mammals the coding sequences of genes (exons) are interrupted by non coding sequences (introns). In higher eukaryotes most genes are interrupted with much longer introns compared to exons creating genes much larger than their coding regions. These introns are however removed by splicing the exons on either side of the introns i.e. following splicing the exons are joined together in the same order in which they are arranged in DNA. So the colinearity of gene and protein is maintained between the individual exons and the corresponding parts of the protein chain. Thus in eukaryotes before the mRNA a preRNA transcript is formed where splicing takes place to form the mRNA which has to be translated into proteins. The linear sequence of nucleotides in a gene determines the linear sequence of amino acids in a protein.