There's no single answer to how many bases a real mRNA molecule has because the length of mRNA molecules can vary greatly depending on the gene they are transcribed from.

Here's why:

* Genes vary in size: Some genes are very short, while others are incredibly long.

* Splicing: After transcription, mRNA molecules often undergo splicing, where non-coding regions (introns) are removed. This can significantly change the length of the final mRNA.

Here are some general guidelines:

* Short mRNA: Molecules for small proteins might have a few hundred bases.

* Average mRNA: A typical mRNA molecule could range from a few hundred to several thousand bases.

* Long mRNA: Some mRNA molecules, especially those for large proteins, can be tens of thousands of bases long.

In summary: The number of bases in an mRNA molecule is highly variable and depends on the specific gene and its processing.