Question

In humans, the X and Y chromosomes are involved in sex determination: XX individuals are female, and XY individuals are male. Accordingly, Y chromosomes are present only in males and are passed only from fathers to sons.

Mitochondria have their own genome, consisting of a single circular chromosome. Mitochondria are inherited only through the cytoplasm of the oocyte, so they are passed on by the mother, not the father.

In human populations, both Y chromosomal DNA and mitochondrial DNA (mtDNA) may show genetic variation. The unique modes of inheritance of Y chromosomal DNA and mtDNA mean that specific variants of either may be lost more easily from human populations over time than autosomal DNA variants. This effect has shaped the genetic variation of present-day human populations.

In this tutorial, you will compare inheritance patterns of Y chromosomal DNA variation, mtDNA variation, and autosomal DNA variation in a single extended family. You will then apply the results of this comparison to evidence from paleogenomics (the recovery and sequencing of genomes of extinct organisms) relating to interbreeding between humans and other hominin species.

Part A - Tracing inheritance of Y chromosomal DNA

The pedigree from Part A is shown below. Three Y chromosomal DNA variants are present in generation I, each variant represented by a different color. The dashed lines indicate a mating to an individual in the same generation on the opposite side of the pedigree.

For the males in generations II through V, indicate which Y chromosomal DNA variant they inherited by dragging one of the yellow, purple, or green labels to each target in the pedigree. Then complete the statements below the pedigree by dragging one white label (with the number 1, 2, or 3) to each statement. Labels may be used once, more than once, or not at all.

Answer 1