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Protein synthesis in an animal cell occurs -
A
On ribosomes present in cytoplasm as well as in mitochondria
B
On ribosomes present in the nucleolus as well as in cytoplasm
C
Only on ribosomes attached to the nuclear envelope and endoplasmic reticulum
D
Only on the ribosomes present in cytosol
Detailed Solution
Ribosomes are the sites of protein synthesis.
In an animal cell, 80S ribosomes are present in the cytoplasm, either free in the cytosol or attached to the endoplasmic reticulum and the outer nuclear membrane.
Mitochondria contain their own DNA and their own 70S ribosomes, on which some mitochondrial proteins are synthesised.
So protein synthesis occurs on ribosomes present in the cytoplasm as well as in mitochondria.
The nucleolus is the site of synthesis of rRNA and of the assembly of ribosomal subunits, not of protein synthesis.
The words 'only' make the last two statements wrong, since both free and bound ribosomes, as well as mitochondrial ribosomes, synthesise proteins.
In an animal cell, 80S ribosomes are present in the cytoplasm, either free in the cytosol or attached to the endoplasmic reticulum and the outer nuclear membrane.
Mitochondria contain their own DNA and their own 70S ribosomes, on which some mitochondrial proteins are synthesised.
So protein synthesis occurs on ribosomes present in the cytoplasm as well as in mitochondria.
The nucleolus is the site of synthesis of rRNA and of the assembly of ribosomal subunits, not of protein synthesis.
The words 'only' make the last two statements wrong, since both free and bound ribosomes, as well as mitochondrial ribosomes, synthesise proteins.