why cant DNA synthesis in 3' -5' end in replication?

Answer 1

Human DNA polymerases which replicate single-stranded DNA do not have the 3'-5' activity.

Some bacterial polymerase do have this action however.

It has to do with the phosphate groups are being hydroxilized to bind to the next nucleotide, the reverse biochemical reaction cannot be catalyzed by our polymerases

Answer 2

D.N.A POLYMERASE CAN'T REPLICATE IN 3-5 DIRECTION HENCE WHEN SUCH A CASE ARISE D.N.A IS FRAGMENTED SO YHERE ARE SEVERAL STRANDS WITH 5-3 DIRECTION & THEY ARE LATER SEALED BY ENZYMES.

Answer 3

because there is no phosphate group to add the next base on to