M itosis and cytokinesis • Figure 3.2 0
Drawings and light micrographs (700X) show
cells in each stage of mitosis.
Identical cells carry out normal functions and
grow until the next division. They are exactly the
same as the original starting cell.
all at 700x
Cell carries out its normal functions. As mitosis approaches, the
cell prepares for division by making new proteins, copying the
entire DNA, and making new organelles. Cells spend most of their
time in interphase. Some cells become arrested in interphase and
do not divide unless stimulated (for example, muscle cells, liver
cells), while other cells do not divide at all once arrested (such as
nerve cells). In contrast, some cells are constantly dividing (such
as skin cells, cells lining the intestine).
Cleavage furrow .
Chromatids at opposite ends decondense into
chromatin, a nuclear envelope forms around them, and
new nucleoli appear. The cytoplasm pinches in the
middle (cleavage furrow) and divides (cytokinesis) to
form two separate but identical cells.
68 CHAPTER 3
Cells and Tissues