Question

Mitochondria are semi-autonomous as they possess
(a) DNA
(b) DNA + RNA
(c) DNA + RNA + Ribosomes
(d) Proteins

Answer 1

Hint: These are genetic materials along with a structure responsible for protein synthesis possessed by mitochondria so that it will be independent for their multiplication.

Correct step by step answer:
The mitochondrion is a semi- autonomous double- membrane- bound organelle possessing DNA, RNA, and ribosomes and is found in most eukaryotic organisms, earlier they were independent free- living organisms and later on became lodged in eukaryotic cells as endosymbionts. That is why they are called autonomous. They are not dependent on the nucleus for their multiplication but can increase in number by fission like bacteria.

Additional Information:
- In multicellular organisms, some cells lack mitochondria such as in RBC.
- The mitochondrion is surrounded by double membranes, having their own independent genome that shows substantial similarity to bacterial genomes.
- The mitochondrial genome codes for some RNAs of ribosomes, and the 22 tRNAs necessary for the translation of mRNAs into protein.
- It contains their own DNA which is circular like a prokaryotic chromosome, has their own ribosomes which are 70S type like prokaryotic ribosomes, and has their own protein- synthesizing machinery comprising required types of RNA.
- The ribosomes coded by the mitochondrial DNA are similar to those ribosomes found in bacteria in size and structure.
- The ribosomes coded for by the mitochondrial DNA are almost like those from bacteria in size and structure.
- Mitochondria generate most of the cell's supply of adenosine triphosphate (ATP) , used as a source of chemical energy, thus it is termed as the powerhouse of the cell.
- In addition to supplying cellular energy, mitochondria are involved in other tasks, like signaling, cellular differentiation, and necrobiosis, also as maintaining control of the cell cycle and cell growth. - The most prominent roles of mitochondria are to supply the energy currency of the cell, ATP (i.e., phosphorylation of ADP) , through respiration, and to manage cellular metabolism.
So, the correct answer is,’DNA + RNA + Ribosomes’.

Note:
- They closely resemble the bacterial 70S ribosome and can code by its own DNA and, not like the 80S cytoplasmic ribosomes, which are coded for by nuclear DNA.
- Mitochondrial proteins vary counting on the tissue and therefore the species.
- The central set of reactions involved in ATP production are collectively referred to as the acid cycle or the Krebs cycle.