Question

1) You read a paper that says, “The symbiotic alpha-proteobacterium that first took up residence in an early eukaryote would have had a genome that codes for at least 500 proteins and RNAs.” No evidence is provided to backup this assertion. Where do you think the estimate of 500 genes cae form?

2) What is the definition of multicellularity? What are the benefits of multicellularity? What evidence do we have that multicellularity evolved multiple times?

3) What are some of the evolutionary advantages of sex -- why mix your own awesome genes with someone else’s? What are some of the disadvantages?

Answer 1

**Please note the misprint in the question. It is not ‘500 genes’; it is ‘500 proteins’.

Answer 1)

Bacterial genomes have atleast (i.e. minimum) size of 130Kbp of genome. This accounts to 130*10^3bp. It has been investigated by researchers that one protein is made up of minimum 100 amino acids i.e. 300bp. So, 130*10^3/3 = 43.3* 10^3 or 43300 amino acids. This will finally account to atleast 433 proteins.

So, the scientists assumed that a minimum of 500 proteins must be present in the proteo-bacteria which resided in symbiotic association in the early eukaryotic cells.