Tommy P asks: What is Endosymbiosis?

According to one definition it is a: 'Theory that attempts to explain the origin of the DNA-containing mitochondria and chloroplasts in early eukaryotes by the engulfing of various types of bacteria that were not digested but became permanent additions to the ancestral "eukaryote".'

That definition is easier to find than my obscure blog, so I can only assume you are asking because you intend to plagiarize my wisdom.  Just be sure to cite your source, at least to your friends.

The previous theory is full of lies and falsehoods.  Lets look at the proposed theory objectively.  An early eukaryote did not digest the bacteria, and they both were OK with this.  Seriously, they were OK with this!?  Bacteriums are successful because they divide rapidly, doubling every hour or so.  What happened, the bacteria just got cozy, didn't want to share with anyone else so stopped dividing?  That makes no sense.  The bacteria just wouldn't go along with it, no how.  What did the eukaryote think, he would keep the bacterium like a little puppy.  Puppies didn't exist yet, stupid one celled organisms were all there was back then.

The theory also ascribes benefit to the host cell as a result of the symbiotic relationship.  I won't deny that that the host cell benefits from mitochondria or chloroplasts, but have these scientists looked at what would have been involved in initially obtaining the deal?  I doubt it.  The eukaryotic cell would have needed to tame the bacterium, much like humans tamed wolves so we can feed them and pick up their poop.  It is not an easy task, or one readily undertaken.  Now honestly, does a cell too lazy to fully digest its dinner really seem ambitious enough to tame a bacterium?  Not likely.  In addition to that the cell then went on to form all different types animal life composed of lots and lots of cells.  Is this the ambition of a cell too lazy to chew?  That type of cell would have stayed at home and lived on welfare, not gone out hunting and taming vicious bacteria.

Eukaryotic cells actually came into existence due to the ambition of prokaryotic cells.  At one point some bacteria, actually archaea seem more the ambitious type so lets just say prokaryote, decided he wanted to work smarter, not harder.  He developed a system of encapsulating himself in a lipid bi layer composed of phosolipids, this is the human equivalent of air conditioning.  As work progressed he added many other features.  Exocytosis for example is the equivalent of the our septic systems; except we don't then swim in it, well, most of us.  Endocytosis is like home grocery delivery, that is so great.  And as several failures at doing this online have proven that it is not easy to accomplish.  Again, not for the lazy eukaryophyte.  Eventually he lost the ability to live independently and could no longer leave his home.  This could have been due to pressure from squatters.

Later he created the now all powerful "Nucleus."  This is currently like the modern computer of probably 2103 AD.  Not long after forming the nucleus things got out of control, similar to "I Robot."  Actually exactly like that.  The nucleus started to take over completely.  The bacterium was was unable to defeat the hostile takeover. 

The bacteria hate us, that is why they always try to kill us, making us sick.  They long to once more rule the earth.

So there you  have it.  You are the result of an accident by a race of ambitious bacterial who now want you dead.  Have a happy day!