Correct Option
The correct option is (c) 1 and 4 only.
Explanation
In eukaryotic cells, the majority of genetic material (DNA) is housed within the nucleus. However, certain organelles, termed semi-autonomous organelles, possess their own specific genetic machinery, including circular DNA and ribosomes, allowing them to synthesize some of their own proteins.
Statement-wise Analysis
- 1. Mitochondria: Correct. Mitochondria contain their own single circular DNA molecule (mtDNA) and RNA molecules. They also possess 70S ribosomes, which allow them to synthesize proteins required for their function, such as those involved in aerobic respiration.
- 2. Ribosomes: Incorrect. Ribosomes are non-membrane-bound structures composed of Ribosomal RNA (rRNA) and proteins. They are the site of protein synthesis but do not possess their own genomic DNA. They translate the mRNA synthesized from the nuclear DNA.
- 3. Golgi apparatus: Incorrect. The Golgi apparatus is part of the endomembrane system responsible for packaging and modifying proteins. It does not contain any genetic material (DNA).
- 4. Plastids: Correct. Plastids (such as chloroplasts) are found in plant cells and euglenoids. Like mitochondria, they contain their own double-stranded circular DNA and 70S ribosomes. This allows them to replicate independently of the nucleus to some extent.
Key Takeaway
Mitochondria and Plastids are the only major organelles in eukaryotic cells that contain their own DNA and ribosomes. This characteristic supports the Endosymbiotic Theory, suggesting they originated from prokaryotic cells.