Last night I watched the most recent episode on Terminator: The Sarah Connor Chronicles.  I've been giving the show a lot of slack regarding basic things like their own internal consistency, because I really wanted it to get better.  Last night, I decided that it won't.

Allow me to paraphrase the scene that did me in:

Set Up:  Derek Reese, brother of the famous Kyle Reese and therefore uncle of John Connor, has been shot.  He's coughing up blood and looking like he's done for.

Paramedic Guy: He's lost a lot of blood.  He needs a transfusion.  His blood type is AB and that's really rare.
River...errrr, I mean...the perky li'l Terminator: Sarah Connor is type O negative.
Paramedic Guy: That's no good.  He needs at least three units of his own type!
Me, sitting on the couch: Ummm...why is that exactly?
John Connor: Ooo...oo! Test me!  See if I'm a match!
Me, seeing where this is heading: no, No, NO!!!!

Wrap Up:  Of course John is a match and Derek gets his transfusion.  Everyone is happy...ish.

Here are my problems: 

1. AB is the universal receiver, they can literally take blood from any blood group (minor exceptions exist, but do you really care?)

2. O neg is the universal donor, they can give blood to anyone (again, minor exceptions)

3. There are three possible flavors for the blood type gene: A, B and O.  Everyone gets one gene from each parent.  The only way for someone to be type AB is to get an A from one parent and a B from the other.  Now, pay attention.  Here comes the tricky part: both A and B are dominant to O.  Since Sarah is type O, she only has Os to give to John.  Therefore and ergo, John CANNOT be type AB.

Now I get the fact that not everyone has the qualifications to work in a blood bank, like I do.  But I seem to remember learning the basics of the ABO system in high school.  Even if that's too much to expect from today's public education, why in the name of all that is cute and fuzzy didn't the writers call in a science consultant when they were writing about something that they clearly didn't understand?  I mean, this is basic real-world science, not something that is open to debate like the effects of time travel on a fluid time stream!

This ends my rant.  Thank you for tuning in.