The mosaic nature is due to the numerous proteins that
are entrenched in the phospholipids bilayer, fluctuate in shape, size and
patterns in the same way as the stones or tiles of a mosaic.
the flexibility is due to individual phospholipids molecules which can move virtual
to one another and gives the membrane a flexible structure that is constantly
changing shape
I think the cauae of substitution they involve swapping of one nucleotide for another during DNA repliction.For example,during repliction,a thymine nucleotide might be inserted in placed of a guanine nucleotide
