Some of the “C” words

What is a Chromosome? Structure containing the genetic material (DNA) within a cell Are always present in a cell, but usually are too thin to be seen

Chromosome Structure DNA exists in the form of CHROMATIN for most of the cell’s life Long strands of DNA wrapped around protein molecules When a cell is getting ready to divide, chromatin coils, thickening and shortening to form CHROMOSOMES

Chromosome Structure CHROMATID – exact copies of DNA CENTROMERE – holds sister chromatids together

Chromosome Number How many chromosomes are in each of your cells? Humans = 46 23 from mother’s egg, 23 from father’s sperm AUTOSOMES – chromosome pairs 1-22 “Non-sex” chromosomes SEX CHROMOSOMES – pair #23 Determines the sex/gender of individual XX = female XY = male

Karyotypes A picture showing all chromosomal pairs for an individual