Question

1. Mitochondria and chloroplasts were once free-living bacteria that later migrated into eukaryotic cells. Mitochondria make energy while chloroplasts prepare their own food.

1. How can a mitochondrion live by itself? Explain your answer by mentioning the specific processes that this organelle performs.
2. What does a chloroplast do to survive in its free living condition? What important chemicals does it need froma sorrounding primordial soup to prepare its own food?
3. Apart from the process by which chloroplasts prepare their own food, what other vital process protects it from dying in an acidic environment?
4. The DNA inside these organelles would have helped them make their own proteins. But, now inside eukaryotic cells, they do not make proteins. So after moving into the eukaryotes, what are the cellular structures that dissapeared? (Clue: these are involved in protein synthesis both in bacteria and higher life forms).

Answer 1

a). A mitochondrion has its own DNA to code proteins for its own survival. In addition, it’s double membrane structure has proteins for the electron transport which provides a source of ATP to run all life sustaining metabolic reactions.

b). A chloroplast has components to make its own food for surviving independently. It uses sunlight, atmospheric CO2 and water(from the surrounding) to generate glucose molecules which can later be oxidised to generate energy for survival.

c). It has proton pumps in it’s inner membrane which pumps out H⁺ ions thereby managing internal pH thereby tolerating acidic environments. These proteins pumps are critical to generate the proton motive force to drive the ATPase rotation.

additionally, vacuoles sequester H⁺ thereby regulating chloroplast pH

d). They lost structures involved in translation like ribosomes and tRNAs.