9.
Chromosomes, The Cell Cycle, and Cell Division
180
9.1
How Do Prokaryotic and Eukaryotic
Cells Divide? 181
Prokaryotes divide by binary fission
181
Eukaryotic cells divide by mitosis
or meiosis 182
9.2
How Is Eukaryotic Cell Division Controlled?
184
Cyclins and other proteins trigger
events in the cell cycle 184
Growth factors can stimulate cells
to divide 186
9.3
What Happens during Mitosis? 187
Eukaryotic DNA is packed into very
compact chromosomes 187
Overview: Mitosis segregates exact
copies of genetic information 188
The centrosomes determine the plane
of cell division 188
Chromatids become visible and the
spindle forms during prophase 189
Chromosome movements are highly organized
189
Nuclei re-form during telophase 191
Cytokinesis is the division of the
cytoplasm 192
9.4
What Is the Role of Cell Division
in Sexual Life Cycles? 193
Reproduction by mitosis results in
genetic constancy 193
Reproduction by meiosis results in
genetic diversity 193
The number, shapes, and sizes of the
metaphase chromosomes constitute the
karyotype 195
9.5
What Happens When a Cell Undergoes
Meiosis? 195
The first meiotic division reduces
the chromosome number 197
The second meiotic division separates
the chromatids 199
The activities and movements of chromosomes
during meiosis result in genetic diversity
199
Meiotic errors lead to abnormal chromosome
structures and numbers 199
Polyploids can have difficulty in
cell division 200
