Answer to Question #232247 in Genetics for Ket

Question

Genes are certain segments of the DNA molecule and occupy a specific place on the chromosome. What is calculated to be the average size of the gene?

Answer 1

Human chromosomes range in size from about 50,000,000 to 300,000,000 base pairs. Because the bases exist as pairs, and the identity of one of the bases in the pair determines the other member of the pair, scientists do not have to report both bases of the pair.

A gene is a region of the DNA that is transcribed. Typically a gene should have a transcription start site dictated by a promoter and a transcription stop site marked by termination signals (like terminators and poly-A signal etc.)

There are some little RNAs (~18nt) that are produced from TSS of usual genes but are probably products of failed elongation. These are not really considered genes as they are heterogeneous in size and are not marked by any boundary.