Koala's are diploid organisms where 2n=16. How many total pairs of sister chromatids are there in a koala cell that is in prophase of meiosis I? (consider a pair of sister chromatids as a single unit)

16 pairs of sister chromatids

Explanation:

Prior to cell division, the genetic material of the cell undergoes replication in the interphase stage. The chromosomes duplicate to form sister chromatids held at the centromere.

In kaola's case whose cell contains 16 chromosomes, the chromosomes undergo replication to produce 16 pairs of sister chromatids or 32 chromatids. Each sister chromatid is considered a chromosome at the Prophase stage of meiosis I until they separate at meiosis II, where each chromatid is regarded as an individual chromosome in the daughter cells.

Hence, at Prophase of meiosis I, 16 replicated chromosomes or 16 pairs of sister chromatids. Separation of homologous chromosomes occur in Anaphase of meiosis I to produce 8 chromosomes but 8 pair (16) of sister chromatids in each cell.

Each sister chromatid gets separated in meiosis II to result in 8 chromatids regarded as 8 chromosomes in each cell.