Transcript Modules08-04to08-11 - Lincoln Park High School

BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 8
The Cellular Basis of
Reproduction and Inheritance
Modules 8.4 – 8.11
From PowerPoint® Lectures for Biology: Concepts & Connections
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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
– The genes are grouped into
multiple chromosomes,
found in the nucleus
– The chromosomes of this
plant cell are stained
dark purple
Figure 8.4A
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• Chromosomes contain a very long DNA
molecule with thousands of genes
– Individual chromosomes are only visible
during cell division
– They are packaged as chromatin
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• Before a cell starts
dividing, the
chromosomes are
duplicated
– This process
produces sister
chromatids
Sister chromatids
Centromere
Figure 8.4B
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• When the cell
divides, the sister
chromatids separate
Chromosome
duplication
– Two daughter
cells are produced
– Each has a
complete and
identical set of
chromosomes
Sister
chromatids
Centromere
Chromosome
distribution
to
daughter
cells
Figure 8.4C
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
8.5 The cell cycle multiplies cells
• The cell cycle consists of two major phases:
– Interphase, where chromosomes duplicate
and cell parts
are made
– The mitotic
phase, when
cell division
occurs
Figure 8.5
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8.6 Cell division is a continuum of dynamic
changes
• Eukaryotic cell division consists of two stages:
– Mitosis
– Cytokinesis
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• In mitosis, the duplicated chromosomes are
distributed into two daughter nuclei
– After the chromosomes coil up, a mitotic spindle
moves them to the middle of the cell
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INTERPHASE
PROPHASE
Centrosomes
(with centriole pairs)
Early mitotic
spindle
Centrosome
Chromatin
Nucleolus Nuclear
envelope
Plasma
membrane
Chromosome,
consisting of two
sister chromatids
Figure 8.6
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Fragments
of nuclear
envelope
Centrosome
Kinetochore
Spindle
microtubules
• The sister chromatids then separate and move
to opposite poles of the cell
– The process of cytokinesis divides the cell into
two genetically identical cells
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METAPHASE
ANAPHASE
Cleavage
furrow
Metaphase
plate
Spindle
TELOPHASE AND CYTOKINESIS
Daughter
chromosomes
Figure 8.6 (continued)
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Nuclear
envelope
forming
Nucleolus
forming
8.7 Cytokinesis differs for plant and animal cells
• In animals, cytokinesis
occurs by cleavage
Cleavage
furrow
– This process pinches
the cell apart
Cleavage
furrow
Figure 8.7A
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Contracting ring of
microfilaments
Daughter cells
• In plants, a
membranous cell
plate splits the cell in
two
Cell plate
forming
Wall of
parent cell
Cell wall
Figure 8.7B
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Vesicles containing
cell wall material
Daughter
nucleus
New cell wall
Cell plate
Daughter
cells
8.8 Anchorage, cell density, and chemical growth
factors affect cell division
• Most animal cells divide only when stimulated,
and others not at all
• In laboratory cultures, most normal cells divide
only when attached to a surface
– They are anchorage dependent
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• Cells continue dividing until they touch one
another
– This is called density-dependent inhibition
Cells anchor to dish surface and
divide.
When cells have formed a
complete single layer, they stop
dividing (density-dependent
inhibition).
If some cells are scraped away,
the remaining cells divide to fill
the dish with a single layer and
then stop (density-dependent
inhibition).
Figure 8.8A
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• Growth factors are proteins secreted by cells
that stimulate other cells to divide
After forming a single layer, cells
have stopped dividing.
Providing an additional supply of
growth factors stimulates further
cell division.
Figure 8.8B
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8.9 Growth factors signal the cell cycle control
system
• Proteins within the cell control the cell cycle
– Signals affecting critical checkpoints determine
whether the cell will go through a complete cycle
and divide
G1 checkpoint
Control
system
M checkpoint
G2 checkpoint
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Figure 8.9A
• The binding of growth factors to specific
receptors on the plasma membrane is usually
necessary for cell division
Growth factor
Plasma membrane
Receptor
protein
Relay
proteins
Signal
transduction
pathway
Figure 8.8B
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G1 checkpoint
Cell cycle
control
system
8.10 Connection: Growing out of control, cancer
cells produce malignant tumors
• Cancer cells have abnormal cell cycles
– They divide excessively and can form abnormal
masses called tumors
• Radiation and chemotherapy are effective as
cancer treatments because they interfere with
cell division
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• Malignant tumors can invade other tissues and
may kill the organism
Lymph
vessels
Tumor
Glandular
tissue
Metastasis
1
A tumor grows
from a single
cancer cell.
2
Cancer cells invade
neighboring tissue.
Figure 8.10
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3
Cancer cells spread
through lymph and
blood vessels to other
parts of the body.
8.11 Review of the functions of mitosis: Growth,
cell replacement, and asexual reproduction
• When the cell cycle operates normally, mitotic
cell division functions in:
– Growth (seen here in an onion root)
Figure 8.11A
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• Cell replacement (seen here in skin)
Dead
cells
Epidermis,
the outer
layer of the
skin
Dividing
cells
Dermis
Figure 8.11B
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• Asexual reproduction (seen here in a hydra)
Figure 8.11C
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings