Download Chapter 9: Chromosomes, the Cell Cycle, and Cell Division

Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
CHAPTER 9
Chromosomes, the Cell Cycle,
and Cell Division
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Chapter 9: Chromosomes, the
Cell Cycle, and Cell Division
Systems of Cell Reproduction
Interphase and the Control of Cell Division
Eukaryotic Chromosomes
Mitosis: Distributing Exact Copies of Genetic
Information
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Chapter 9: Chromosomes, the
Cell Cycle, and Cell Division
Cytokinesis: The Division of the Cytoplasm
Reproduction: Sexual and Asexual
Meiosis: A Pair of Nuclear Divisions
Meiotic Errors
Cell Death
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Cell Division
• Cell division is necessary for reproduction,
growth, and repair of an organism.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Systems of Cell Reproduction
• Cell division must be initiated by a
reproductive signal and consists of three
steps:
replication of the genetic material
(DNA)
 partitioning of the two DNA
molecules
 division of the cytoplasm

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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Systems of Cell Reproduction
• In prokaryotes, cellular DNA is a single
molecule, or chromosome.
• Prokaryotes reproduce by cell fission.
Review Figure 9.3
6
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure
9.3
Figure 9.3
figure 09-03.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Systems of Cell Reproduction
• In eukaryotes, nuclei divide by either
mitosis or meiosis.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Interphase and the Control of
Cell Division
• The mitotic cell cycle has two main phases:
interphase and mitosis.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Interphase and the Control of
Cell Division
• During most of the cell cycle the cell is in
interphase, which is divided into three
subphases: S, G1, and G2.
• DNA is replicated during S phase.
Review Figure 9.4
10
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure 9.4
Figure 9.4
figure 09-04.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Interphase and the Control of
Cell Division
• Cyclin-Cdk complexes regulate the passage
of cells from G1 into S phase and from G2
into M phase.
Review Figure 9.5
12
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure
9.5
Figure 9.5
figure 09-05.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Interphase and the Control of
Cell Division
• In addition to the internal cyclin-Cdk
complexes, controls external to the cell,
such as growth factors and hormones, can
also stimulate a division cycle.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Eukaryotic Chromosomes
• Chromosomes contain DNA and proteins.
• At mitosis, chromosomes initially appear
double because two sister chromatids are
held together at the centromere.
• Each sister chromatid consists of one
double-stranded DNA molecule complexed
with proteins and referred to as chromatin.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Eukaryotic Chromosomes
• During interphase, DNA in chromatin is
wound around histone cores to form
nucleosomes.
• DNA folds repeatedly, packing within the
nucleus. When mitotic chromosomes form,
it folds even more.
Review Figure 9.7
16
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure
9.7
Figure 9.7
figure 09-07.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Mitosis: Distributing Exact
Copies of Genetic Information
• After DNA is replicated during S phase, the
first sign of mitosis is the separation of
centrosomes, which initiate microtubule
formation for the spindle.
Review Figure 9.9
18
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure
9.9
Figure 9.9
figure 09-09.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Mitosis: Distributing Exact
Copies of Genetic Information
• Mitosis can be divided into phases:
prophase
 metaphase
 anaphase
 telophase

Review Figure 9.8
20
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure 9.8 –
Part 1
Figure 9.8 – Part 1
figure 09-08a.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure 9.8
– Part 2
Figure 9.8 – Part 2
figure 09-08b.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Mitosis: Distributing Exact
Copies of Genetic Information
• During prophase, the chromosomes
condense and appear as paired chromatids.
• Centrioles move to the poles.
• Spindle fibers form.
• Chromosomes move toward the middle of
the cell.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Mitosis: Distributing Exact
Copies of Genetic Information
• In Metaphase, chromosomes line up on
the equator and their centromeres attach
to a spindle fiber.
• At Anaphase, chromatid pairs separate and
migrates to opposite poles.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Mitosis: Distributing Exact
Copies of Genetic Information
• During telophase, the chromosomes uncoil.
• The nuclear membranes re-form, producing two
nuclei identical to each other and the original cell.
• The cytoplasm then divides.
Review Figure 9.8
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Cytokinesis: The Division of
the Cytoplasm
• Cytokinesis usually follows nuclear division.
• Animal cells pinch in to divide cytoplasm.
• In plant a new cell wall is built.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Reproduction: Sexual and
Asexual
• Asexual reproduction produces an organism
genetically identical to the parent.
• Any genetic variety is the result of
mutations.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Reproduction: Sexual and
Asexual
• In sexual reproduction, two haploid
gametes—one from each parent—unite in
fertilization to form a genetically unique,
diploid zygote.
Review Figure 9.12
29
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure 9.12
– Part 1
Figure 9.12 – Part 1
figure 09-12a.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure 9.12
– Part 2
Figure 9.12 – Part 2
figure 09-12b.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure
9.12 – Part
3
Figure 9.12 – Part 3
figure 09-12c.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Reproduction: Sexual and
Asexual
• In sexually reproducing organisms, certain
cells in the adult undergo meiosis, whereby
a diploid cell produces haploid gametes.
• Each gamete contains a random mix of one
of each pair of homologous chromosomes
from the parent.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Reproduction: Sexual and
Asexual
• The number, shapes, and sizes of the
chromosomes constitute the karyotype of an
organism.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Meiosis: A Pair of Nuclear
Divisions
• Meiosis reduces the chromosome number
from diploid to haploid and ensures that
each haploid cell contains one member of
each chromosome pair.
• It consists of two nuclear divisions.
Review Figure 9.14
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure 9.14
– Part 1
Figure 9.14 – Part 1
figure 09-14a.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure 9.14
– Part 2
Figure 9.14 – Part 2
figure 09-14b.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Meiosis: A Pair of Nuclear Divisions
• During prophase I homologous chromosomes pair,
and crossing over occurs between homologs.
• In metaphase I, the paired homologs line up at the
equatorial.
• Both chromosomes attach to the same spindle fiber.
• In anaphase I, chromosome pairs split and move to
the poles.
• After Telophase I, there are two haploid cells.
Review Figures 9.14, 9.16
38
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure
9.16
Figure 9.16
figure 09-16.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Meiosis: A Pair of Nuclear
Divisions
• In meiosis II, the sister chromatids
separate.
• No DNA replication precedes this division.
• The result of meiosis is four haploid cells.
Review Figures 9.14, 9.17
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure 9.17 –
Part 1
Figure 9.17 – Part 1
figure 09-17a.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Figure
9.17 –
Part 2
Figure 9.17 – Part 2
figure 09-17b.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Meiosis: A Pair of Nuclear
Divisions
• Both crossing over and the independent
assortment of chromosomes ensure that the
genetic composition of gametes is different
from that of the parent and other gametes.
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Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Meiotic Errors
• In non-disjunction, one member of a
homologous pair of chromosomes fails to
separate from the other, and both go to the
same pole.
• Fertilization with a normal haploid gamete
results in aneuploidy and genetic
abnormalities that are invariably harmful or
lethal.
Review Figure 9.18
44
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
figure 09-18.jpg
Figure
9.18
Figure 9.18
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Cell Death
• Cells may die by necrosis or may selfdestruct by apoptosis, a genetically
programmed series of events that includes
the detachment of the cell from its
neighbors and the fragmentation of its
nuclear DNA.
Review Figure 9.19
46
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
figure 09-19.jpg
Figure
9.19
Figure 9.19