branches chain lipids occur in d cell membranes of

1. archaebacteria
2. mycoplasma
3. actinomycetes
4. streptomyces

The correct option is 1.
Archaea were initially classified as bacteria, receiving the name archaebacteria (in Kingdom Monera), but this classification is outdated. Archaeal cells have unique properties separating them from the other two domains of life: Bacteria and Eukaryota. The Archaea are further divided into four recognized phyla. Classification is difficult because the majority have not been studied in the laboratory and have only been detected by analysis of their nucleic acids in samples from their environment.