Q. Thermococcus, Methanococcus and Methanobacterium exemplify
A) Bacteria that contain a cytoskeleton and ribosomes
B) Archaebacteria that contain protein homologous to eukaryotic core histones
C) Archaebacteria that lack any histones resembling those found in eukaryotes but whose DNA is negatively supercoiled
D) Bacteria whose DNA is relaxed or positively supercoiled but which have a cytoskeleton as well as mitochondria
Explanation
[Solution from source] These genera are methanogenic and hyperthermophilic archaebacteria, and many euryarchaea such as these carry small histone proteins clearly homologous to the eukaryotic core histones (H3/H4 fold) that wrap their DNA. The statement that they lack any eukaryote-like histones is therefore wrong; hyperthermophiles like Thermococcus also tend to have relaxed or positively supercoiled DNA owing to reverse gyrase. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.