什么是 Karyotype, centromere, telomere？

The karyotype is the set of chromosomes of a cell, sorted by size and banding pattern: humans have 23 pairs (22 autosomes and XY or XX), $6.4 \times 10^{9}$ base pairs in all, $2.2\,\mathrm{m}$; the largest chromosome holds $250\,\mathrm{Mb}$, the smallest $50\,$. Each linear chromosome carries a centromere, the constricted region where the two copies stay joined after replication and where the spindle attaches (Chapter 18), and two telomeres, repeated sequences at the ends that protect them from being taken for broken DNA and from shortening at each replication.