Question

where do the lipids and proteins constituting the cell membrane get synthesised

Answer 1

in the mitochondria & also in ribosomes tgat r present in the cytoplasm

hope it helpss

Answer 2

Proteins are synthesised by ribosomes in and on the endoplasmic reticulum. They do this by reading the mRNA and rRNA (the codes for combination of amino acids which combines to make protein).
Lipids are synthesised in the Smooth Endoplasmic Reticulum.
Hope it helps.