5' 3' DNA

[michyd]

what does the 5' and 3' mean when learning about DNA!!!

[biohazard]

The 5' and 3' mean "five prime" and "three prime", which in turn indicate the carbon numbers in the DNA's sugar backbone. The 5' carbon has a phosphate group attached to it and the 3' carbon a hydroxyl group. This asymmetry gives a DNA strand a "direction". For example, DNA polymerase works in a 5' -> 3' direction, that is, it adds nucleotides to the 3' end of the molecule (the -OH group), thus advancing to that direction.