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Section 1: Meiosis
Section 2: Mendelian Genetics
Section 3: Gene Linkage and Polyploidy
Chapter 10 Sexual Reproduction
and Genetics
Human body cells have
46 chromosomes
10.1 Meiosis
Sexual Reproduction and Genetics
Each parent contributes
23 chromosomes
Chapter 10
Homologous
chromosomes—one of
two paired
chromosomes, one from
each parent
Chromosomes and Chromosome Number Chromosomes and Chromosome Number
10.1 Meiosis
Sexual Reproduction and Genetics
Same length
Same centromere position
Carry genes that control the same inherited traits
Chapter 10
Haploid and Diploid Cells
Human gametes contain
23 chromosomes.
Sexual Reproduction and Genetics
10.1 Meiosis
An organism produces
gametes to maintain
the same number of
chromosomes from
generation to
generation.
Chapter 10
Haploid and Diploid Cells
Sexual Reproduction and Genetics
A cell with n
chromosomes is called
a haploid cell.
A cell that contains 2n
chromosomes is called
a diploid cell.
10.1 Meiosis
Chapter 10
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Meiosis I
The sexual life cycle
in animals involves
meiosis.
Sexual Reproduction and Genetics
Meiosis produces
gametes.
10.1 Meiosis
When gametes
combine in fertilization, the number of
chromosomes is restored.
Chapter 10
Stages of Meiosis I
Reduces the chromosome
number by half through the
separation of homologous
chromosomes
Sexual Reproduction and Genetics
Involves two consecutive
cell divisions called meiosis
I and meiosis II
10.1 Meiosis
Chapter 10
Meiosis I
Sexual Reproduction and Genetics
10.1 Meiosis
Interphase
Chromosomes replicate.
Chromatin condenses.
Chapter 10
Interphase
Meiosis I
Sexual Reproduction and Genetics
10.1 Meiosis
Prophase I
Pairing of homologous chromosomes occurs.
Each chromosome consists of two chromatids.
The nuclear envelope breaks down.
Spindles form.
Chapter 10
Prophase I
Meiosis I
Sexual Reproduction and Genetics
10.1 Meiosis
Prophase I
Crossing over produces exchange of genetic
information.
Crossing over—chromosomal segments are
exchanged between a pair of homologous
chromosomes.
Chapter 10
Meiosis I
Sexual Reproduction and Genetics
10.1 Meiosis
Metaphase I
Chromosome centromeres attach
to spindle fibers.
Homologous chromosomes line up at the equator.
Chapter 10
Metaphase I
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Meiosis I
Sexual Reproduction and Genetics
10.1 Meiosis
Anaphase I
Chapter 10
Anaphase I
Homologous chromosomes
separate and move
to opposite poles of the cell.
Meiosis I
Sexual Reproduction and Genetics
10.1 Meiosis
Telophase I
The spindles break down.
Chromosomes uncoil and form two nuclei.
The cell divides.
Chapter 10
Telophase I
Meiosis II
Prophase II
Sexual Reproduction and Genetics
10.1 Meiosis
Chapter 10
A second set of phases begins
as the spindle apparatus forms and the chromosomes condense.
Prophase II
Meiosis II
Metaphase II
Sexual Reproduction and Genetics
10.1 Meiosis
Chapter 10
A haploid number of chromosomes
line up at the equator.
Metaphase II
Meiosis II
Sexual Reproduction and Genetics
10.1 Meiosis
Anaphase II
Chapter 10
Anaphase II
The sister chromatids are
pulled apart at the centromere by spindle fibers and move toward the opposite poles
of the cell.
Sexual Reproduction and Genetics
10.1 Meiosis
Meiosis II
Chapter 10
Telophase II
The chromosomes reach the poles, and
the nuclear membrane and nuclei reform.
Telophase II
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Meiosis II
Sexual Reproduction and Genetics
Cytokinesis results in four haploid cells,
each with n number of
chromosomes.
10.1 Meiosis
Visualizing
Meiosis I and Meiosis II
Chapter 10
Cytokinesis
The Importance of Meiosis
Meiosis consists of two sets
of divisions
Sexual Reproduction and Genetics
Produces four haploid
daughter cells that are not
identical
10.1 Meiosis
Results in genetic variation
Mitosis and
Meiosis
Chapter 10
Sexual Reproduction and Genetics
Meiosis Provides Variation
Depending on how the
chromosomes line up at the
equator, four gametes with
four different combinations
of chromosomes can result.
Genetic variation also is
produced during crossing
over and during fertilization,
when gametes randomly
combine.
10.1 Meiosis
Chapter 10 Sexual Reproduction and Genetics
Sexual Reproduction v. Asexual Reproduction
Asexual reproduction
The organism inherits all of its chromosomes from a single parent.
The new individual is genetically identical to its parent.
Sexual reproduction
Beneficial genes multiply faster over time.
10.1 Meiosis
Chapter 10
Gregor Mendel Father of Genetics
Austrian monk who
formulated the basis of modern genetics
1822-1884
1900 his paper
rediscovered
Genetics- The branch
of biology that studies heredity.
Why did Mendel choose pea plants?
1) Many varieties exist.
Easy to distinguish traits.
2) Small, easy to grow
plants that mature quickly
3) Self-pollination
4) Easy to cross
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Pollination
Self Pollination – fertilizing itself
Cross Pollination – breeding between two
flowers
Self Pollination Cross Pollination
Mendel’s Experimental Design Step 1
Ensure True Breeding – allow each variety to self-pollinate
These plants are the parental generation or
P - Generation
Mendel’s Experimental Design Step 2
Cross pollinate two varieties from the P generation
that had different traits.
The offspring are called the first filial generation or
F1 generation
P
F1
Mendel’s Experimental Design Step 3
Allow the F1 generation to self pollinate
Offspring are called F2 generation
Mendel counted these plants.
F1
F2
Mendel’s Observations
Classified the trait expressed in the F1 generation the dominant trait.
The trait not expressed in the F1 generation is the recessive trait.
When the F1 generation was allowed to self pollinate, the recessive trait reappeared in some of the F2 plants.
At this point Mendel counted the F2 generation and noticed a 3:1 ratio
F2 Self Pollination Results
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F2 Self Pollination Results
Plants showing recessive traits were true
breeding (all recessive)
Plants showing dominant traits only 1 was
true breeding
The actual ratio is 1:2:1 (1 true dominant: 2
not true dominant: 1 true recessive)
Mendel proposed a Theory of Heredity
1) Parents do not transmit traits directly to
their offspring.
* Genes are passed on to the offspring that
operates in the offspring to produce the
trait.
Mendel proposed a Theory of Heredity
2) For each trait, an individual has two
alleles,1 from mother and 1 from father.
Allele – copy of a factor, or gene
Homozygous - both genes have the same
information
Heterozygous – genes are different
Mendel proposed a Theory of Heredity
3) Phenotype: Physical appearance
Genotype: Set of genes that an individual has
4) An individual receives an allele from each parent
5) The presence of an allele does not mean the trait will be expressed in heterozygous individuals, only the dominant allele is expressed.
Mendel proposed a Theory of Heredity
We can represent an allele by a letter. In
the case of the pea plants let’s assign Y for
the yellow pea gene and y for the green
pea gene.
Y,y are the alleles, the offspring received 1
from each parent.
YY and yy are homozygous
Yy is heterozygous
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Mendel proposed a Theory of Heredity
Phenotype Genotype
YY Yellow Pea Homozygous Yellow Pea
YY
Yy Yellow Pea Heterozygous Yellow Pea
Yy
yy Green Pea Homozygous Green Pea
yy
Sexual Reproduction and Genetics Chapter 10
Mendel studied seven different traits.
Sexual Reproduction and Genetics
Seed or pea color
Flower color
Seed pod color
Seed shape or texture
Seed pod shape
Stem length
Flower position
10.2 Mendelian Genetics
Chapter 10
Mendel’s Law of Segregation
Sexual Reproduction and Genetics
Two alleles for each trait separate during meiosis.
During fertilization, two alleles for that trait unite.
Heterozygous organisms are called hybrids.
10.2 Mendelian Genetics
Chapter 10
Monohybrid Cross
Sexual Reproduction and Genetics
A cross that involves hybrids for a single
trait is called a
monohybrid cross.
10.2 Mendelian Genetics
Chapter 10 Sexual Reproduction and Genetics
Dihybrid Cross
The simultaneous inheritance of two or more traits in the same plant is a dihybrid cross.
Dihybrids are heterozygous for both traits.
10.2 Mendelian Genetics
Chapter 10
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Sexual Reproduction and Genetics
Law of Independent Assortment
Random distribution of alleles occurs during gamete formation
Genes on separate chromosomes sort independently during meiosis.
Each allele combination is equally likely to occur.
10.2 Mendelian Genetics
Chapter 10
Probability
Probability – The likelihood that a specific event will
occur.
# of one kind of possible outcome
Total # of all possible outcomes
Formula can be used to predict the outcome of a genetic cross.
Sexual Reproduction and Genetics
Punnett Squares
Predict the possible offspring of a cross
between two known
genotypes
10.2 Mendelian Genetics
Punnett
Squares
Chapter 10 Sexual Reproduction and Genetics
Punnett Square—
Dihybrid Cross
Four types of alleles from
the male gametes and
four types of alleles from
the female gametes can
be produced.
The resulting phenotypic
ratio is 9:3:3:1.
10.2 Mendelian Genetics
Chapter 10
How to build Punnett Square
Monohybrid Heterozygous Example
Rabbits black coat is dominant (B) over brown (b)
Step 1 Figure out the genotype of the parental generation.
Step 2 Draw a table with all possible allele combinations of 1 parent across the top and the other up and down to the left
B
b
Sperm
Egg
Parent’s Genotype
Bb (egg) X Bb (sperm)
B b
How to built Punnett Square
Monohybrid Heterozygous Example
Rabbits black coat is dominant (B) over brown (b)
Step 3 Fill in Punnet Square
Step 4 Figure out genotype and phenotype
BB Bb
Bb bb
B
b
Sperm
Egg
B b Genotype
1 BB, 2 Bb, 1 bb
Phenotype
3 black, 1 brown
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You Solve!
Rabbits black coat is dominant (B) over brown (b)
Cross a Homozygous black coat rabbit with a
Heterozygous black coat rabbit. (BB X Bb)
BB BB
Bb Bb
B
b
Sperm
Egg
B B
Genotype
2 BB, 2 Bb
Phenotype
All black
How to build Punnett Square
Dihybrid Heterozygous Example
Rabbits S=Short hair s=long hair
B=Black b=brown
Step 1 Figure out the genotype of the parental generation.
Step 2 Draw a table with all possible allele combinations of 1 parent across the top and the other up and down to the right
Parent’s Genotype
SsBb (egg) X SsBb
(sperm)
SB
Sb
sB
sb
SB Sb sB sb
How to built Punnett Square
Dihybrid Heterozygous Example
Guinea Pigs S=Short hair s=long hair
B=Black b=brown
Step 3 Fill in Punnet Square
Step 4 Figure out genotype and phenotype
SSBB SSBb SsBB SsBb
SSBb SSbb SsBb Ssbb
SsBB SsBb ssBB ssBb
SsBb Ssbb ssBb ssbb
SB
Sb
sB
sb
SB Sb sB sb
Genotype
Listed on black board
Phenotype
Listed on black board
You Solve!
Rabbits black coat is dominant (B) over brown (b) and Short hair (S) over long hair (s)
Cross a Heterozygous Short Black hair rabbit with a Homozygous Short Black hair rabbit (SsBb X SSBB)
SSBB SSBB SSBB SSBB
SSBb SSBb SSBb SSBb
SsBB SsBB SsBB SsBB
SsBb SsBb SsBb SsBb
SB
Sb
sB
sb
SB SB SB SB Genotype
4 SSBB, 4 SSBb
4 SsBB, 4 SsBb
Phenotype
All black short haired.
Genetic Recombination
The new combination of genes produced by crossing over and independent assortment
10.3 Gene Linkage and Polyploidy
Sexual Reproduction and Genetics
Combinations of genes due to independent assortment can be calculated using the
formula 2n, where n is the number of
chromosome pairs.
Chapter 10
Gene Linkage
The linkage of genes on a chromosome results
in an exception to Mendel’s law of independent
assortment because linked genes usually do not
segregate independently.
Sexual Reproduction and Genetics
10.3 Gene Linkage and Polyploidy
Chapter 10
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Polyploidy
Sexual Reproduction and Genetics
Polyploidy is the occurrence of one or more extra
sets of all
chromosomes
in an organism.
A triploid organism,
for instance, would
be designated 3n,
which means that
it has three complete sets of chromosomes.
10.3 Gene Linkage and Polyploidy
Chapter 10 Sexual Reproduction and Genetics
Chapter Resource Menu
Chapter Diagnostic Questions
Formative Test Questions
Chapter Assessment Questions
Standardized Test Practice
biologygmh.com
Glencoe Biology Transparencies
Image Bank
Vocabulary
Animation Click on a hyperlink to view the corresponding lesson.
Chapter 10
A. #
B. x
C. r
D. n
Which symbol is used to represent the number of chromosomes in a gamete?
Sexual Reproduction and Genetics Chapter 10
Chapter Diagnostic
Questions
A. Felix Mendelssohn
B. Gregor Mendel
C. Dr. Reginald Punnett
D. Albert Einstein
Name the person known as the father of genetics.
Sexual Reproduction and Genetics Chapter 10
Chapter Diagnostic
Questions
A. gamete
B. hybrid
C. phenotype
D. genotype
Which term refers to the outward expression of an allele pair?
Sexual Reproduction and Genetics Chapter 10
Chapter Diagnostic
Questions
Segments of DNA that control the production of proteins are called _______.
Sexual Reproduction and Genetics
A. chromatids
B. chromosomes
C. genes
D. traits
Chapter 10
10.1 Formative
Questions
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What is the term for a pair of chromosomes
that have the same length, same centromere
position, and carry genes that control the same
traits?
Sexual Reproduction and Genetics
A. diploid
B. heterozygous
C. homozygous
D. homologous
Chapter 10
10.1 Formative
Questions
How does the number of chromosomes in gametes compare with the number of
chromosomes in body cells?
Sexual Reproduction and Genetics Chapter 10
10.1 Formative
Questions
Sexual Reproduction and Genetics Chapter 10
10.1 Formative
Questions
A. Gametes have 1/4 the number of
chromosomes.
B. Gametes have 1/2 the number of
chromosomes.
C. Gametes have the same number of
chromosomes.
D. Gametes have twice as many
chromosomes.
What type of organisms only reproduce asexually?
Sexual Reproduction and Genetics
A. bacteria
B. protists
C. plants
D. simple animals
Chapter 10
10.1 Formative
Questions
What is the name for different forms of a single gene that are passed from generation
to generation?
Sexual Reproduction and Genetics
A. alleles
B. genotypes
C. phenotypes
D. traits
Chapter 10
10.2 Formative
Questions
Which pair of alleles is heterozygous?
Sexual Reproduction and Genetics
A. RR
B. Rr
C. rr
D. yR
Chapter 10
10.2 Formative
Questions
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In rabbits, gray fur (G) is dominant to black
fur (g). If a heterozygous male is crossed with
a heterozygous female, what is the phenotypic
ratio of the possible offspring?
Sexual Reproduction and Genetics
A. 1:1
B. 1:2:1
C. 2:1
D. 3:1
Chapter 10
10.2 Formative
Questions
Which explains how the shuffling of genes
during meiosis results in billions of possible
combinations?
Sexual Reproduction and Genetics
A. crossing over
B. gene linkage
C. genetic recombination
D. independent segregation
Chapter 10
10.3 Formative
Questions
True or False
Two genes on the same chromosome may
become separated during meiosis.
Sexual Reproduction and Genetics Chapter 10
10.3 Formative
Questions
What is the term for an organism that has one
or more sets of extra chromosomes in its cells?
Sexual Reproduction and Genetics
A. diploid
B. gamete
C. hybrid
D. polyploid
Chapter 10
10.3 Formative
Questions
A. 6
B. 12
C. 24
D. 36
How many chromosomes would a cell have
during metaphase I of meiosis if it has 12
chromosomes during interphase?
Sexual Reproduction and Genetics Chapter 10
Chapter Assessment
Questions
A. prophase I
B. interphase
C. anaphase I
D. anaphase II
Which stage of meiosis is illustrated?
Sexual Reproduction and Genetics Chapter 10
Chapter Assessment
Questions
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What is the next step for the chromosomes
illustrated?
Sexual Reproduction and Genetics Chapter 10
Chapter Assessment
Questions
A. Chromosomes replicate.
B. Chromosomes move to opposite poles.
C. Chromosomes uncoil and form two nuclei.
D. Chromosomes line up at the equator.
Sexual Reproduction and Genetics Chapter 10
Chapter Assessment
Questions
What is this process called?
Sexual Reproduction and Genetics
A. fertilization
B. gamete formation
C. inheritance
D. reproduction
Chapter 10
Standardized Test
Practice
Before meiosis I, the sister chromatids of
this chromosome were identical. What
process caused a change in a section of
one chromatid?
Sexual Reproduction and Genetics
A. DNA replication
B. crossing over
C. synapsis
D. telophase
Chapter 10
Standardized Test
Practice
At what stage is the chromosome number
reduced from 2n to n?
Sexual Reproduction and Genetics
A. prophase I
B. metaphase I
C. anaphase I
D. meiosis II
Chapter 10
Standardized Test
Practice
To which step in this process does the law of
segregation apply?
Sexual Reproduction and Genetics Chapter 10
Standardized Test
Practice
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Sexual Reproduction and Genetics
A. grows into plant
B. gamete formation
C. fertilization
D. seed development
Chapter 10
Standardized Test
Practice
For human eye color, brown is dominant and
blue is recessive. If a husband is heterozygous
and his wife has blue eyes, what is the
probability that their child will have blue eyes?
Sexual Reproduction and Genetics
A. 0
B. 1/4
C. 1/2
D. 1
Chapter 10
Standardized Test
Practice
Sexual Reproduction and Genetics Chapter 10
Glencoe Biology Transparencies
Sexual Reproduction and Genetics Chapter 10
Image Bank
Sexual Reproduction and Genetics Chapter 10
Image Bank
gene
homologous
chromosome
gamete
haploid
fertilization
diploid
meiosis
crossing over
Sexual Reproduction and Genetics Chapter 10
Vocabulary
Section 1
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genetics
allele
dominant
recessive
homozygous
heterozygous
genotype
phenotype
law of segregation
hybrid
law of independent
assortment
Sexual Reproduction and Genetics Chapter 10
Vocabulary
Section 2
genetic recombination
polyploidy
Sexual Reproduction and Genetics Chapter 10
Vocabulary
Section 3
Visualizing Meiosis I and Meiosis II
Generations
Sexual Reproduction and Genetics Chapter 10
Animation
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