Download the eukaryotic cell cycle and mitosis

Chapter 8
The Cellular Basis of
Reproduction and Inheritance
PowerPoint Lectures for
Biology: Concepts and Connections, Fifth Edition
– Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Rain Forest Rescue
• Scientists in Hawaii
– Have attempted to “rescue” endangered
species from extinction
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• The goals of these scientists were
– To promote reproduction to produce more
individuals of specific endangered plants
Kauai, Hawaii
Cyanea kuhihewa
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• In sexual reproduction
– Fertilization of sperm and egg produces
offspring
• In asexual reproduction
– Offspring are produced by a single parent,
without the participation of sperm and egg
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CONNECTIONS BETWEEN CELL DIVISION AND REPRODUCTION
8.1 Like begets like, more or less
• Some organisms reproduce asexually
Figure 8.1A
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LM 340
– And their offspring are genetic copies of
the parent and of each other
• Other organisms reproduce sexually
– Creating a variety of offspring
Figure 8.1B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
8.2 Cells arise only from preexisting cells
• Cell division is at the heart of the reproduction of
cells and organisms
– Because cells come only from preexisting cells
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8.3 Prokaryotes reproduce by binary fission
• Prokaryotic cells
– Reproduce asexually by cell division
Colorized TEM 32,500
Prokaryotic chromosomes
Figure 8.3B
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• As the cell
Prokaryotic
replicates its
chromosome
single chromosome,
the copies move apart
Plasma
membrane
Cell wall
– And the growing
membrane then
divides the cells
3
Figure 8.3A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
1
Duplication of chromosome
and separation of copies
2
Continued elongation of the
cell and movement of copies
Division into
two daughter cells
THE EUKARYOTIC CELL CYCLE AND MITOSIS
8.4 The large, complex chromosomes of
eukaryotes duplicate with each cell division
• A eukaryotic cell has many more genes than a
prokaryotic cell
– And they are grouped into multiple
chromosomes in the nucleus
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• Individual chromosomes contain a very long DNA
molecule associated with proteins
– And are visible only when the cell is in the
process of dividing
• If a cell is not undergoing division
Figure 8.4A
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LM 600
– Chromosomes
occur in the
form of thin,
loosely packed
chromatin fibers
Chromatin and chromosomes
Most of the time, chromosomes
exist as a diffuse mass of thin
fibers – chromatin.
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“Beads on
a string”
Linker
Nucleosome
(10-nm diameter)
Tight helical fiber
(30-nm diameter)
Supercoil
(300-nm diameter)
700
nm
TEM
Figure 11.4
Histones
TEM
Chromatin is a combination of
DNA and proteins. The DNA
molecule is wrapped like string
on a “yo-yo” around proteins
called histones. Several of
these are called nucleosomes
and under a microscope look
like beads on a string.
DNA double
helix (2-nm
diameter)
Metaphase chromosome
• Before a cell starts dividing, the chromosomes
replicate
Sister chromatids
– Producing sister
chromatids joined
together at the
centromere
TEM 36,000
Centromere
Figure 8.4B
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• Cell division involves the separation of sister
chromatids
– And results in two
daughter cells,
each containing
a complete and
Centromere
identical set of
chromosomes
Chromosome
duplication
Sister
chromatids
Chromosome
distribution
to
daughter
cells
Figure 8.4C
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8.5 The cell cycle multiplies cells
• The cell cycle consists of two major phases
INTERPHASE
G1
S
(DNA synthesis)
G2
Figure 8.5
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• During interphase
– Chromosomes duplicate and cell parts are
made
• During the mitotic phase
– Duplicated chromosomes are evenly
distributed into two daughter nuclei
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8.6 Cell division is a continuum of dynamic
changes
• In mitosis, after the chromosomes coil up
– A mitotic spindle moves them to the middle
of the cell
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• The sister chromatids then separate
– And move to opposite poles of the cell,
where two nuclei form
• Cytokinesis, in which the cell divides in two
– Overlaps the end of mitosis
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LM 250
• The stages of cell division
INTERPHASE
PROPHASE
Centrosomes
(with centriole pairs)
Chromatin
Early mitotic
spindle
PROMETAPHASE
Centrosome
Fragments
of nuclear
envelope
Kinetochore
Nucleolus
Nuclear
envelope
Chromosome, consisting
Plasma
membrane ot two sister chromatids
Figure 8.6 (Part 1)
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Centromere
Spindle
microtubules
ANAPHASE
METAPHASE
Cleavage
furrow
Metaphase
plate
Spindle
TELOPHASE AND CYTOKINESIS
Daughter
chromosomes
Figure 8.6 (Part 2)
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Nuclear
envelope
forming
Nucleolus
forming
8.7 Cytokinesis differs for plant and animal cells
• In animals
Cleavage
furrow
Cleavage furrow
Figure 8.7A
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SEM 140
– Cytokinesis occurs
by a constriction of
the cell (cleavage)
Contracting
ring of
microfilaments
Daughter cells
• In plants
Cell plate
forming
Wall of
parent cell
Daughter
nucleus
TEM 7,500
– A membranous cell
plate splits the cell
in two
Cell wall
Vesicles containing
cell wall material
Figure 8.7B
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New cell wall
Cell plate
Daughter cells
• The binding of growth factors to specific receptors
on the plasma membrane
– Is usually necessary for cell division.
Growth factor
Plasma membrane
Receptor
protein
Signal
transduction
pathway
Relay
proteins
G1 checkpoint
Control
system
G1
M
Figure 8.9B
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G2
S