Trisomy 21, or Down syndrome, occurs when there is a normal diploid chromosomal complement but one (extra) chromosome 21. Given the fact that embryos with 48 chromosomes (four #21 chromosomes) are not likely to survive early development, what percentage of surviving offspring would be expected to have Down syndrome if both parents have Down syndrome?     all     2/3     1/2     1/3     none

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Q: chromosomes

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Mitochondrial Mutations

A mitochondrion is a cellular organelle that serves as the site for cellular respiration and energy production (ATP or Adenosine Triphosphate). It is a double-membrane-bound organelle and is only present in eukaryotic cells.