Mitochondrial DNA differs from nuclear DNA in that: its nitrogenous bases includ
ID: 72217 • Letter: M
Question
Mitochondrial DNA differs from nuclear DNA in that:
its nitrogenous bases include adenine, cytosine, guanine, and uracil.
it has an extra histone protein associated with it leading to greater supercoiling.
it lacks repair mechanisms, introns, and does not cross over.
it is found in the lysosomes of eukaryotic cells.
it is identical in every cell of a multicellular organism.
its nitrogenous bases include adenine, cytosine, guanine, and uracil.
it has an extra histone protein associated with it leading to greater supercoiling.
it lacks repair mechanisms, introns, and does not cross over.
it is found in the lysosomes of eukaryotic cells.
it is identical in every cell of a multicellular organism.
Explanation / Answer
Each mitochondrion contains numerous copies of genome within the matrix. The number of copies varies depending on the energy requirement of the cell. Usually the number varies between 2 to 10. In human cells the mitochondrial genome is about 16.5kb in size and these accounts only to ~1/100000th the length of haploid genome of a human gamete which is a circular DNA molecule carrying 37 genes. Of these 37 genes, 13 genes encode polypeptide subunits of the protein complexes required for oxidative phosphorylation apparatus. The mitochondrial gene contains 22 tRNA genes and two genes encoding large and small subunits of rRNA found in mitochondrial ribosomes. The mitochondrail genomes generally do not contain noncoding sequences or introns like that in nuclear genome. This is the major difference between mitochondrial and nuclear genomes. Hence, option 3 is correct.