Question

5. Mitochondria and chloroplasts were once free-living bacteria that later migrated into eukaryotic cells. Mitochondria make energy while chloroplasts prepare their own food. a) If Gregor Mendel were a molecular biologist and laid his hands on a free-living mitochondrion, would he have got his 3:1 ratio crossing two mitochondria? b) In its free-living condition, can a chloroplast code for proteins, and if yes, what are the two most important enzymes that aid in its survival? c) After endosymbiosis, what happenned to the independent genes of the free living mitochondria and chloroplasts?

Answer 1

a) Mitochondria were once the free-living bacteria. The bacteria reproduce asexually. Due to this, when bacteria reproduce, then its daughter cells will be the same as the parents and with each other. So, here mendelian ration is not 3:1, but is 1:1.

b) In living conditions, chloroplast can produce proteins.  Two RNA polymerases are used in this process by the chloroplasts.

c) During endosymbiosis, the circular DNA of mitochondria and chloroplast remains independent.