Why is the proteome larger than the genome?
A) Proteins may be modified by covalent addition of a variety of molecules
B) Not all genes are expressed in all cells at the same time
C) Many coding genes are transcribe into mRNA which can be alternatively spliced, and those transcripts produce different proteins so the ratio of the number of protein molecules the number of genes is greater than 1.
D) The total amount of protein in a cell as measured by mass is always greater than the total amount of DNA.

Question

Quizplus · Accepted Answer

Many coding genes are transcribed into mRNA which can be alternatively spliced, and those transcripts produce different proteins so the ratio of the number of protein molecules to the number of genes is greater than 1. Therefore, the proteome can be larger than the genome. A and B are also correct statements, but they do not fully account for the size difference between the proteome and the genome. D is incorrect because the total amount of protein in a cell is not always greater than the total amount of DNA, as DNA is a relatively large molecule.

Why Is the Proteome Larger Than the Genome