ELI5- What are blood groups? Why do they differ from person to person? Why can’t a person of one blood group receive blood from a person of a different blood group?

Question

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In: Biology

Answer 1

Think of it as mixing colors. Your blood can be tagged as either Black, white, red, blue, yellow, green, purple or orange.

If you are “red”, you can donate to other red, orange, purple, or white. All of those “include red”.

If you are “green”, you can receive from green, blue, yellow and black. None of those “add” a color to your green.
But if you donate to someone who’s blue, you poison him with the yellow in your green.

If your color is white, you can accept anything (universal receiver), but will poison anyone who isn’t also white.

And if your blood is black, you can’t poison anyone (universal donor) but any blood that isn’t black will poison yours.