Question

write any three cell organelles which contain their own DNA?

Answer 1

Cell organelles with their own DNA are
★ NUCLEUS
★ MITOCHONDRIA
★ PLASTIDS

Answer 2

The eukaryotic cell organelles that possess their own DNA and ribosomes are only chloroplast and mitochondria. They have 70S ribosomes and single circular chromosome just like prokaryotes. This has an evolutionary significance. It is believed that during the time when a transition from anoxic to oxic earth was occurring, some bacteria were engulfed by larger living cells. Such bacteria were called endosymbionts. This adaptation eliminated the oxygen toxicity to the host cells as the endosymbiotic intracellular bacteria used aerobic respiration to generate ATP and perhaps also conferred some metabolic feat to the host. In return, the host provided the bacteria with abundant nutrients and a safe habitat to live in. Eventually, genes needed for independent living were lost from the endosymbionts and they evolved to become mitochondria. This is hypothesis is popularly known as the Endosymbiotic theory. Mitochondrium is thought to be evolved from an alpha proteobacterium, Rickettsia prowazekii while chloroplast is thought to be evolved from a cyanobacterium called Prochloron.