You Must Know
• The structure of the duplicated chromosome.• The events that occur in the cell cycle (G1, S,
and G2)• The features of mitosis that result in the
production of genetically identical daughter cells including replication, alignment of chromosomes (metaphase), and separation of chromosomes (anaphase).
video
• Mitosis
Figure 9.1 – Chromosomes during cell division
Eukaryotic chromosomes consist of chromatin, a complex of DNA and protein.
Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus.
Somatic cells (nonreproductive cells) have two sets of chromosomes. They are diploid.
Gametes (reproductive cells: sperm and eggs) have one set of chromosomes. They are haploid.
Replicated Chromosome
Centromere 0.5 m
Sisterchromatids
Centromere
ChromosomalDNA moleculesChromosomes
Chromosomearm
1
Sisterchromatids
Chromosomearm
Chromosome duplication
2
Separation of sisterchromatids
3
One chromosome and one DNA molecule.
One chromosome and two DNA molecules.
Two chromosomes and two DNA molecules.
• Eukaryotic cell division consists of– Mitosis, the division of the genetic material in the
nucleus– Cytokinesis, the division of the cytoplasm
• Gametes are produced by a variation of cell division called meiosis.
• Meiosis yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cell. (Haploid cells)
© 2014 Pearson Education, Inc.
The Cell Cycle
Cytokin
esis
Mito
sis
S(DNA synthesis)G1
G2
• Mitosis is conventionally divided into five phases– Prophase– Prometaphase– Metaphase– Anaphase– Telophase
• Cytokinesis overlaps the latter stages of mitosis
© 2014 Pearson Education, Inc.
Figure 9.7c
Centrosomes(with centriolepairs)
G2 of Interphase Prophase
Chromosomes(duplicated,uncondensed)
Early mitoticspindle
CentromereAster
NucleolusPlasmamembrane Two sister chromatids of
one chromosomeNuclearenvelope
Figure 9.7d
PrometaphaseFragmentsof nuclearenvelope
Nonkinetochoremicrotubules
Kinetochoremicrotubule
Kinetochore Spindle Centrosome atone spindle pole
Metaphaseplate
Metaphase
Figure 9.7e
Anaphase Telophase and Cytokinesis
Cleavagefurrow
Nucleolusforming
Nuclearenvelopeforming
Daughterchromosomes
Cytokinesis in an animal cell
Contractile ring ofmicrofilaments
Cleavage furrow
Daughter cells
100 m
New cell wall
Daughter cells
Cell plate
Wall of parentcell
Vesiclesformingcell plate
1 m
Cytokinesis in a plant cell
Figure 9.11
10 m
Nucleus
Telophase
NucleolusChromosomescondensing Chromosomes
Prometaphase
Cell plate
Prophase
AnaphaseMetaphase
1 2
3 4 5