ID #1992

When the mitochondrial mRNA is translated, does that process occur in the mitochondria or does it occur in the cytoplasm? Also, when a cell divides, is the mitochondria divided up equally between daughter cells?

For the first one, yes, the division is done essentially randomly, with approximate numbers being "given" to each daughter cell when it divides. If this division is uneven, that's ok, because mitochondria can divide (much like bacteria do... coincidence?!) and come up to the desired number of mitochondria in the cell. For your comment about chromosomes and genetic blueprints, I know this is kind of a circular argument, or at least a matter of semantics, but by definition if it's part of a chromosome, it's part of the organism's nuclear genome. What happens to those protein products after they're translated doesn't change where the information is maintained. Lastly, a mother passes along mitochondria by having lots of them in the unfertilized egg. When that egg is fertilized by a sperm, the new zygote possesses all the mitochondria the egg had, and virtually no contribution from the sperm. Sperm have a "collar" of fused mitochondria to power their trip to the egg, but that's it. This is why maternal heritage can be determined using mitochondrial DNA analysis, but tells you nothing about paternal heritage.

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