Aging skin begins to wrinkle because the protein (A)__________ becomes more rigid and the protein (B)__________ is reduced.

Normal body cells divide 80 or 90 times before dying. When a cell divides, it makes a copy of its chromosomes so that each resulting daughter cell has a complete set of chromosomes. The ends of chromosomes are capped by segments of DNA called (C)__________. As cells divide little pieces of these capped segments are lost. A cell dies when only a tiny portion remains.