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COLLEGE PHYSICS
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BIOLOGY
Chapter 11 MEIOSIS AND SEXUAL REPRODUCTION
CAMPBELL
BIOLOGYReece • Urry • Cain • Wasserman • Minorsky • Jackson
© 2014 Pearson Education, Inc.
TENTH
EDITION
CAMPBELL
BIOLOGYReece • Urry • Cain • Wasserman • Minorsky • Jackson
TENTH
EDITION
• Meiosis and Sexual Life Cycles
13
Semen attack unsuspecting ovum
Figure 13.1
Asexual Repro - Clones
Aspen tree = cloned
Figure 13.3b
Pair of homologousduplicated chromosomes
Centromere
Sisterchromatids
Metaphasechromosome
5 m
Karyotype
• Homologous chromosomes
• 46 or 23 prs autosomes & sex chromosomes
Human Karyotypes
Diploid Cells Contain Two Homologous Sets of Chromosomes
Section 9.2 Figure 9.4
Homologous pair:• look alike chromosomes• carry the same sequence of
genes for the same traits • ALLELES different versions
Figure 13.4
Sister chromatidsof one duplicatedchromosome
Key
Maternal set ofchromosomes (n 3)
Paternal set ofchromosomes (n 3)
Key
2n 6
Centromere
Two nonsisterchromatids ina homologous pair
Pair of homologouschromosomes (one from each set)
Homologous chromosomes
• Diploid (2n = 46)
• Haploid (1n = 23)
Figure 8.12A/11.8Haploid gametes (n 23)
Egg cell
Sperm cell
Fertilization
n
n
Meiosis
Ovary Testis
Diploidzygote
(2n 46)2n
MitosisKey
Haploid stage (n)
Diploid stage (2n)Multicellular diploid
adults (2n 46)
Figure 13.6b / 11.10
2n2n
n
MEIOSIS FERTILIZATION
Mitosis Mitosis
Mitosis
Gametes
Spores
Zygote
Haploid multi-cellular organism(gametophyte)
Diploidmulticellularorganism(sporophyte)
(b) Plants and some algae
n n nn
Haploid (n)
Diploid (2n)
Key
Alternation of generation
Meiosis Produces Human Gametes
Section 9.8 Figure 9.16
Meiosis Produces Human Gametes
Section 9.8 Figure 9.17
Meiosis Generates Variability
Section 9.5
• Identical twins: embryo splits in two• Each embryo then develops independently
Figure 9.10Identical twins: © Barbara Penoyar/Getty Images RF
Figure 13.7-1
Pair of homologouschromosomes indiploid parent cell
Duplicated pairof homologouschromosomes
Chromosomesduplicate
Sisterchromatids
Diploid cell withduplicatedchromosomes
Interphase
Meiosis Overview
Figure 13.7-2
Pair of homologouschromosomes indiploid parent cell
Duplicated pairof homologouschromosomes
Chromosomesduplicate
Sisterchromatids
Diploid cell withduplicatedchromosomes
Homologouschromosomes separate
Haploid cells withduplicated chromosomes
Meiosis I
1
InterphaseMeiosis Overview
Reduction division
• Homologous chromosome
separated
Figure 13.7-3
Pair of homologouschromosomes indiploid parent cell
Duplicated pairof homologouschromosomes
Chromosomesduplicate
Sisterchromatids
Diploid cell withduplicatedchromosomes
Homologouschromosomes separate
Haploid cells withduplicated chromosomes
Sister chromatidsseparate
Haploid cells with unduplicated chromosomes
Interphase
Meiosis I
Meiosis II
2
1
Meiosis Overview
Reduction division
• Homologous chromosome
separated
Mitotic division
• Sister chromatids
separated
Figure 13.8 /11.6 and 11.7
MEIOSIS I: Separates homologous chromosomes
Prophase I Metaphase I Anaphase ITelophase I and
Cytokinesis
Centrosome(with centriole pair)
Sisterchromatids
Chiasmata
Spindle
Homologouschromosomes
Fragmentsof nuclearenvelope
Duplicated homologouschromosomes (red and blue)pair and exchange segments;2n 6 in this example.
Centromere(with kinetochore)
Metaphaseplate
Microtubuleattached tokinetochore
Chromosomes line upby homologous pairs.
Sister chromatidsremain attached
Homologouschromosomesseparate
Each pair of homologous chromosomes separates.
Cleavagefurrow
Two haploid cellsform; each chromosomestill consists of twosister chromatids.
MEIOSIS I: Separates sister chromatids
Prophase II Metaphase II Anaphase IITelophase II and
Cytokinesis
Sister chromatidsseparate
Haploid daughtercells forming
During another round of cell division, the sister chromatids finally separate;four haploid daughter cells result, containing unduplicated chromosomes.
Meiosis
Figure 13.8a
Prophase I Metaphase I Anaphase I Telophase I andCytokinesis
Centrosome(with centriole pair)
Sisterchromatids
Chiasmata
Spindle
Homologouschromosomes
Fragmentsof nuclearenvelope
Duplicated homologouschromosomes (red and blue)pair and exchange segments;2n 6 in this example.
Centromere(with kinetochore)
Metaphaseplate
Microtubuleattached tokinetochore
Chromosomes line upby homologous pairs.
Sister chromatidsremain attached
Homologouschromosomesseparate
Each pair of homologous chromosomes separates.
Cleavagefurrow
Two haploid cells form; each chromosomestill consists of two sister chromatids.
Interphase
Prophase I• Synapsis
• Tetrad formation
• Crossing over
Figure 13.11-5Prophase Iof meiosis
Nonsister chromatidsheld togetherduring synapsis
Pair of homologs
Chiasma
Centromere
TEM
Anaphase I
Anaphase II
Daughtercells
Recombinant chromosomes
Crossing over
Figure 11.3
Crossing Over – closer look (comparison)Figure 11.3
Metaphase I
• Metaphase plate
• Pairs line up
• Independent assortment
• 2n 223 => 8 million
Figure 13.10-3 / 11.4
Possibility 1 Possibility 2
Two equally probablearrangements ofchromosomes at
metaphase I
Metaphase II
Daughtercells
Combination 1 Combination 2 Combination 3 Combination 4
Genetic variation video
Independent Assortment
Figure 11.4
Anaphase I
• Homologous chromosomes
separate
• Sister chromatids attached
Telophase I & Cytokinesis
• Cleavage furrow
• Cell Plate
• 2 cells
• Haploid
• Sister chromatids
attached
Interkinesis = Half Time
• False interphase
• Reformation of nucleus, nucleolus, etc.
• NO MORE DNA Replication!!!
• Temporary, if it occurs at all
Meiosis II - Prophase II
• Same as prophase of
mitosis
Meiosis II - Metaphase II
• Metaphase plate
• Line up single file
Meiosis II - Anaphase II
• Sister chromatids separate
Meiosis IITelophase II & Cytokinesis
• 4 cells
• haploid
• variation
Figure 11.5Prometaphase & Anaphase Comparison
Figure 13.8b
Prophase II Metaphase II Anaphase IITelophase II and
Cytokinesis
Sister chromatidsseparate
Haploid daughtercells forming
During another round of cell division, the sister chromatids finally separate;four haploid daughter cells result, containing unduplicated chromosomes.
Figure 11.6
Figure 13.9 / 11.7
Prophase
Duplicatedchromosome
MITOSIS
Chromosomeduplication
Parent cell
2n 6
Metaphase
AnaphaseTelophase
2n 2n
Daughter cellsof mitosis
MEIOSIS
MEIOSIS I
MEIOSIS II
Prophase I
Metaphase I
Anaphase ITelophase I
Haploidn 3
Chiasma
Chromosomeduplication Homologous
chromosome pair
Daughter cells of
meiosis I
Daughter cells of meiosis II
n n n n
SUMMARY
Property Mitosis Meiosis
DNAreplication
Number ofdivisions
Synapsis ofhomologouschromosomes
Number of daughter cellsand geneticcomposition
Role in the animal body
Occurs during interphase beforemitosis begins
One, including prophase, metaphase,anaphase, and telophase
Does not occur
Two, each diploid (2n) and geneticallyidentical to the parent cell
Enables multicellular adult to arise fromzygote; produces cells for growth, repair,and, in some species, asexual reproduction
Occurs during interphase before meiosis I begins
Two, each including prophase, metaphase, anaphase,and telophase
Occurs during prophase I along with crossing overbetween nonsister chromatids; resulting chiasmatahold pairs together due to sister chromatid cohesion
Four, each haploid (n), containing half as manychromosomes as the parent cell; genetically differentfrom the parent cell and from each other
Produces gametes; reduces number of chromosomesby half and introduces genetic variability among the gametes
Figure 11.7 – Meiosis & Mitosis Comparison
Spermatogenesis
• Spermatogenesis
• Puberty
• 4 potential sperm
• Acrosome cap
Oogenesis
• Oogenesis
• Prior to birth (7 month)
– Arrested: Prophase I
• Puberty
– Arrested: Metaphase II
• Fertilization
– Completion of meiosis
• Polar bodies
Ovum development
Meiosis Generates Variability
Section 9.5
• Identical twins: embryo splits in two• Each embryo then develops independently
Figure 9.10Identical twins: © Barbara Penoyar/Getty Images RF
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Meiosis I
Meiosis II
nondisjunction
pair of
homologous
chromosomes
Fertilization
Zygote
normal
pair of
homologous
chromosomes
normal
2n + 1 2n + 1 2n – 1 2n – 1
b.a.
2n 2n 2n + 1 2n – 1
nondisjunction
Nondisjunction
Anaphase I
Anaphase II
Nondisjuction & Fertilization
Downs syndrome trisomy 21
a: © Scott Wintrow/Getty Images; b: © CNRI/SPL/Science Source
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
21
extra chromosome 21
Gart
gene
b.a.
Downs Syndrome & Maternal Age
Klinefelter’s Syndrome
Klinefelter’s Syndrome
XYY – Super Male
Figure 8.23A
Deletion
Duplication
Inversion
Reciprocal translocation
Homologous
chromosomes Nonhomologouschromosomes
Chromosomal Alterations
Figure 8.23B
Chromosome 9
Chromosome 22 Reciprocaltranslocation
“Philadelphia chromosome”
Activated cancer-causing gene
Chromosomal Alterations
Reciprocal translocation
Errors Also Occur Within Chromosomes
Section 9.7 Figure 9.14
Mutations in chromosome structure can have major effects on an organism.
Chromosomes: © Addenbrookes Hospital/Science Source