Final answer:
The proteome can exceed the number of genes through processes such as alternative splicing and post-translational modifications, which diversify proteins beyond their gene templates.
Step-by-step explanation:
The proteome of a species contains a larger number of proteins than genes that code for these proteins because of several mechanisms which increase the complexity of proteomics beyond the number of genes. One of the main reasons is the process of alternative splicing, where a single gene can produce multiple mRNA variants, each leading to a different protein.
Additionally, after translation, proteins can undergo various post-translational modifications such as phosphorylation, glycosylation, and ubiquitination, which can modify a protein's function or stability, further diversifying the proteome. Therefore, while genes provide the code, the resulting proteins can exhibit significant diversity due to these processes.
Incorrect options include statements such as proteins coding for other proteins or the existence of proteins not coded by the genome, which do not align with current biological understanding.