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Thermococcus, Methanococcus and Methanobacterium exemplify:
A
bacteria whose DNA is relaxed or positively supercoiled but which have a cytoskeleton as well as mitochondria
B
bacteria that contain a cytoskeleton and ribosomes
C
archaebacteria that contain protein homologous to eukaryotic core histones
D
archaebacteria that lack any histones resembling those found in eukaryotes but whose DNA is negatively supercoiled
Detailed Solution
Thermococcus, Methanococcus and Methanobacterium are archaebacteria (archaea).
Methanococcus and Methanobacterium are methanogens, which produce methane, and Thermococcus is a thermophile living at very high temperatures.
These archaea belong to the group Euryarchaeota, whose DNA is wrapped around proteins that are homologous to the core histones (H2A, H2B, H3 and H4) of eukaryotes.
Their DNA is relaxed or positively supercoiled, which helps to stabilise it at high temperature.
Being prokaryotes, they do not have mitochondria or other membrane-bound organelles, so the statements describing them simply as bacteria with a cytoskeleton and mitochondria are wrong.
So they exemplify archaebacteria that contain protein homologous to eukaryotic core histones.
Methanococcus and Methanobacterium are methanogens, which produce methane, and Thermococcus is a thermophile living at very high temperatures.
These archaea belong to the group Euryarchaeota, whose DNA is wrapped around proteins that are homologous to the core histones (H2A, H2B, H3 and H4) of eukaryotes.
Their DNA is relaxed or positively supercoiled, which helps to stabilise it at high temperature.
Being prokaryotes, they do not have mitochondria or other membrane-bound organelles, so the statements describing them simply as bacteria with a cytoskeleton and mitochondria are wrong.
So they exemplify archaebacteria that contain protein homologous to eukaryotic core histones.