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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 8.1 – 8.3
From PowerPoint® Lectures for Biology: Concepts & Connections
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Parents
Reproduction
Cell Cycle
Cell Division
Life cycle
Inheritance
Daughter
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Parents
Mitosis
Cell Cycle
Cell
Division
Asexual
Reproduction
Sexual
Inheritance
Meiosis
Daughter
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
8.1 Like begets like, more or less
• Some organisms make exact copies of
themselves, asexual reproduction
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8.2 Cells arise only from preexisting cells
• All cells come from cells
• Cellular reproduction is called cell division
– Cell division allows an embryo to develop
into an adult
– It also ensures the continuity of life from one
generation to the next
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8.3 Prokaryotes reproduce by binary fission
• Prokaryotic cells divide asexually
– These cells possess a single chromosome, containing
genes
– The chromosome is replicated
– The cell then divides into two cells, a process called
binary fission
Prokaryotic chromosomes
Figure 8.3B
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• Binary fission of a prokaryotic cell
Plasma
membrane
Prokaryotic
chromosome
Cell wall
Duplication of chromosome
and separation of copies
Continued growth of the cell
and movement of copies
Division into
two cells
Figure 8.3A
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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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• 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
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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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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
Centromere
Spindle
microtubules
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
8.9 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
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.
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Let’s Recapitulate (Recap) what is mitosis:
Mitosis is nuclear
division plus cytokinesis,
and produces two
identical daughter cells
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Images: 1.plant root tip (meristem)
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Images: 2 different phases in mitosis
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Images: 2 different phases in mitosis
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Images: 2 different phases in mitosis
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Parents
Mitosis
Cell Cycle
Cell
Division
Asexual
Reproduction
Sexual
Inheritance
Meiosis
Daughter
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
MEIOSIS AND CROSSING OVER
8.12 Chromosomes are matched in homologous
pairs
• Somatic cells of each
species contain a
specific number
of chromosomes
Chromosomes
Centromere
– Human cells have
46, making up 23
pairs of
homologous
chromosomes
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Sister chromatids
Figure 8.12
• The human
life cycle
Haploid gametes (n = 23)
Egg cell
Sperm cell
MEIOSIS
FERTILIZATION
Diploid
zygote
(2n = 46)
Multicellular
diploid adults
(2n = 46)
Mitosis and
development
Figure 8.13
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MEIOSIS I: Homologous chromosomes separate
INTERPHASE
METAPHASE I
Spindle
attached to
Sites of crossing over
homologous
Spindle chromosomes
Centrosomes
(with
centriole
pairs)
Nuclear
envelope
PROPHASE I
Chromatin
Sister
chromatids
Tetrad
Figure 8.14, part 1
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Centromere
Metaphase
plate
ANAPHASE I
Sister chromatids
remain attached
Homologous
chromosomes separate
MEIOSIS II: Sister chromatids separate
TELOPHASE I
AND CYTOKINESIS
PROPHASE II
METAPHASE II
ANAPHASE II
TELOPHASE II
AND CYTOKINESIS
Cleavage
furrow
Sister
chromatids
separate
Figure 8.14, part 2
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Haploid
daughter cells
forming
MITOSIS
MEIOSIS
PARENT CELL
(before chromosome replication)
Site of
crossing over
PROPHASE I
Tetrad formed
by synapsis of
homologous
chromosomes
PROPHASE
Duplicated
chromosome
(two sister chromatids)
METAPHASE
ANAPHASE
TELOPHASE
2n
Chromosome
replication
Chromosome
replication
2n = 4
Chromosomes
align at the
metaphase plate
Tetrads
align at the
metaphase plate
Sister chromatids
separate during
anaphase
Homologous
chromosomes
separate
during
anaphase I;
sister
chromatids
remain together
2n
Daughter cells
of mitosis
Figure 8.15
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MEIOSIS I
METAPHASE I
ANAPHASE I
TELOPHASE I
Haploid
n=2
Daughter
cells of
meiosis I
No further
MEIOSIS II
chromosomal
replication; sister
chromatids
separate during
anaphase II
n
n
n
n
Daughter cells of meiosis II
Meiosis produces genetic variations : Independent orientation of chromosomes
POSSIBILITY 1
POSSIBILITY 2
Two equally probable
arrangements of
chromosomes at
metaphase I
Metaphase II
Gametes
Combination 1
Combination 2
Figure 8.16
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Combination 3
Combination 4
Coat-color genes
Eye-color genes
Brown
Black
C
E
c
e
White
Pink
Tetrad in parent cell
(homologous pair of
duplicated chromosomes)
Figure 8.17A, B
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C
E
C
E
c
e
c
e
Chromosomes of
the four gametes
Crossing over during prophase I of meiosis
Tetrad
Chaisma
Centromere
Figure 8.18A
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Coat-color
genes
• How crossing over
leads to genetic
recombination
Eye-color
genes
Tetrad
(homologous pair of
chromosomes in synapsis)
1
Breakage of homologous chromatids
2
Joining of homologous chromatids
Chiasma
3
Separation of homologous
chromosomes at anaphase I
4
Separation of chromatids at
anaphase II and completion of meiosis
Parental type of chromosome
Recombinant chromosome
Recombinant chromosome
Parental type of chromosome
Figure 8.18B
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Gametes of four genetic types
ALTERATIONS OF CHROMOSOME NUMBER
AND STRUCTURE
8.19 A karyotype is a photographic inventory of an
individual’s chromosomes
• To study human chromosomes
microscopically, researchers stain and display
them as a karyotype
– A karyotype usually shows 22 pairs of
autosomes and one pair of sex
chromosomes
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• Preparation of a karyotype
Blood
culture
Packed red
And white
blood cells
Hypotonic solution
Stain
White
Blood
cells
Centrifuge
3
2
1
Fixative
Fluid
Centromere
Sister
chromatids
Pair of homologous
chromosomes
4
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5
Figure 8.19
8.20 Connection: An extra copy of chromosome 21
causes Down syndrome
• This karyotype shows three number 21
chromosomes
• An extra copy of chromosome 21 causes Down
syndrome
Figure 8.20A, B
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• The chance of having a Down syndrome child
goes up with maternal age
Figure 8.20C
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8.21 Accidents during meiosis can alter
chromosome number
• Abnormal
chromosome count
is a result of
nondisjunction
– Either
homologous
pairs fail to
separate
during
meiosis I
Nondisjunction
in meiosis I
Normal
meiosis II
Gametes
n+1
n+1
n–1
n–1
Number of chromosomes
Figure 8.21A
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– Or sister chromatids fail to separate during
meiosis II
Normal
meiosis I
Nondisjunction
in meiosis II
Gametes
n–1
n+1
n
Number of chromosomes
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n
Figure 8.21B
• Fertilization after nondisjunction in the mother
results in a zygote with an extra
chromosome
Egg
cell
n+1
Zygote
2n + 1
Sperm
cell
n (normal)
Figure 8.21C
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8.22 Connection: Abnormal numbers of sex
chromosomes do not usually affect survival
• Nondisjunction can also produce gametes with
extra or missing sex chromosomes
– Unusual numbers of sex chromosomes upset the
genetic balance less than an unusual number of
autosomes
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Table 8.22
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• A man with Klinefelter syndrome has an extra
X chromosome
Poor beard
growth
Breast
development
Underdeveloped
testes
Figure 8.22A
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• A woman with Turner syndrome lacks an X
chromosome
Characteristic
facial
features
Web of
skin
Constriction
of aorta
Poor
breast
development
Underdeveloped
ovaries
Figure 8.22B
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8.23 Connection: Alterations of chromosome
structure can cause birth defects and cancer
• Chromosome breakage can lead to
rearrangements that can produce genetic
disorders or cancer
– Four types of rearrangement are deletion,
duplication, inversion, and translocation
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Deletion
Duplication
Homologous
chromosomes
Inversion
Reciprocal
translocation
Nonhomologous
chromosomes
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Figure 8.23A, B
• Chromosomal changes in a somatic cell can
cause cancer
– A chromosomal translocation in the bone
marrow is associated with chronic myelogenous
leukemia
Chromosome 9
Chromosome 22
Reciprocal
translocation
“Philadelphia chromosome”
Activated cancer-causing gene
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Figure 8.23C
Parents
Mitosis
Cell Cycle
Cell
Division
Asexual
Reproduction
Sexual
Inheritance
Meiosis
Daughter
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings