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Section:
The Father of Genetics –
Gregor Johann Mendel (1822-1884)
1863 - 1866
Mendel cultivated and tested
some 28 000 pea plants
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Section:
Allele – Different form of a gene
Dominant allele - In a heterozygote, the allele that is
fully expressed in the phenotype.
Recessive allele - In a heterozygote, the allele that
is completely masked in the phenotype.
Phenotype – The outward appearance of a trait
Genotype – The combination of alleles (Letters)
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Section:
Mendel’s Experiments
•Used 34 "true-breeding" strains of the common garden
pea plant
•These strains differed from each other in very
pronounced (visible) ways so that there could be no
doubt as the results of a given experiment.
•Pea plants were perfect for such experiments since
their flowers had both male (anthers) and female
(pistils) flower parts
•The flower petals never open therefore no foreign
pollen could enter and back crosses (self fertilization)
was easy.
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Section:
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Section:
Flower Parts
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Section:
Principles of Dominance
Section 11-1
P Generation F1 Generation F2 Generation
Tall Short Tall Tall Tall Tall Tall Short
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Section:
Principles of Dominance
Section 11-1
P Generation F1 Generation F2 Generation
Tall Short Tall Tall Tall Tall Tall Short
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Section:
Principles of Dominance
Section 11-1
P Generation F1 Generation F2 Generation
Tall Short Tall Tall Tall Tall Tall Short
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Section:
Figure 11-3 Mendel’s Seven F1 Crosses
on Pea Plants
Section 11-1
Seed Seed Seed Coat Pod Pod Flower Plant
Shape Color Color Shape Color Position Height
Round Yellow Gray Smooth Green Axial Tall
Wrinkled Green White Constricted Yellow Terminal Short
Round Yellow Gray Smooth Green Axial Tall
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Section:
Section Outline
Section 11-2
11–2 Probability and Punnett Squares
A. Genetics and Probability
B. Punnett Squares
C. Probability and Segregation
D. Probabilities Predict Averages
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Section:
Tt X Tt Monohybrid Cross
Section 11-2
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Section:
Tt X Tt Cross
Section 11-2
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Section:
Monohybrid
Cross
Phenotypes
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Section:
Law of
Segregation
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Section:
Section Outline
Section 11-3
11–3 Exploring Mendelian Genetics
A. Independent Assortment
1. The Two-Factor Cross: F1
2. The Two-Factor Cross: F2
B. A Summary of Mendel’s Principles
C. Beyond Dominant and Recessive Alleles
1. Incomplete Dominance
2. Codominance
3. Multiple Alleles
4. Polygenic Traits
D. Applying Mendel’s Principles
E. Genetics and the Environment
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Section:
Concept Map
Section 11-3
Gregor
Mendel
experimented concluded
with that
Pea “Factors” Some alleles Alleles are
plants determine dominant, separated during
traits & some alleles
recessive gamete formation
which is which is
called the called the
Law of Law of
Dominance Segregation
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Section:
Figure 11-10 Independent Assortment in Peas
Section 11-3
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Section:
Dihybrid Cross
Section 11-2
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Section:
Figure 11-11 Incomplete Dominance in
Four O’Clock Flowers
Section 11-3
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Section:
Figure 11-11 Incomplete Dominance in
Four O’Clock Flowers
Section 11-3
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Section:
Section Outline
Section 11-4
11–4 Meiosis
A. Chromosome Number
B. Phases of Meiosis
1. Meiosis I
2. Meiosis II
C. Gamete Formation
D. Comparing Mitosis and Meiosis
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Section:
Homologous
Chromosome
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Section:
Crossing-Over
Section 11-4
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Section:
Crossing-Over
Section 11-4
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Section:
Crossing-Over
Section 11-4
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Section:
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Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
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Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
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Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
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Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
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Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
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Section:
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two The chromosomes line up in a The sister chromatids Meiosis II results in four
haploid (N) daughter cells, similar way to the metaphase separate and move toward haploid (N) daughter cells.
each with half the number of stage of mitosis. opposite ends of the cell.
chromosomes as the original.
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Section:
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two The chromosomes line up in a The sister chromatids Meiosis II results in four
haploid (N) daughter cells, similar way to the metaphase separate and move toward haploid (N) daughter cells.
each with half the number of stage of mitosis. opposite ends of the cell.
chromosomes as the original.
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Section:
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two The chromosomes line up in a The sister chromatids Meiosis II results in four
haploid (N) daughter cells, similar way to the metaphase separate and move toward haploid (N) daughter cells.
each with half the number of stage of mitosis. opposite ends of the cell.
chromosomes as the original.
Go to
Section:
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two The chromosomes line up in a The sister chromatids Meiosis II results in four
haploid (N) daughter cells, similar way to the metaphase separate and move toward haploid (N) daughter cells.
each with half the number of stage of mitosis. opposite ends of the cell.
chromosomes as the original.
Go to
Section:
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two The chromosomes line up in a The sister chromatids Meiosis II results in four
haploid (N) daughter cells, similar way to the metaphase separate and move toward haploid (N) daughter cells.
each with half the number of stage of mitosis. opposite ends of the cell.
chromosomes as the original.
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Section:
Genetic Recombination
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Section:
Interest Grabber
Section 11-5
Forever Linked?
Some genes appear to be inherited together, or “linked.” If two genes
are found on the same chromosome, does it mean they are linked forever?
Study the diagram, which shows four genes labeled A–E and a–e, and
then answer the questions on the next slide.
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Section:
Interest Grabber continued
Section 11-5
1. In how many places can crossing over result in genes A and b being on
the same chromosome?
2. In how many places can crossing over result in genes A and c being on
the same chromosome? Genes A and e?
3. How does the distance between two genes on a chromosome affect the
chances that crossing over will recombine those genes?
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Section:
Section Outline
Section 11-5
11–5 Linkage and Gene Maps
A. Gene Linkage
B. Gene Maps
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Section:
Comparative Scale of a Gene Map
Section 11-5
Mapping of Earth’s Mapping of Cells,
Features Chromosomes, and Genes
Cell
Earth
Country Chromosome
State Chromosome
fragment
Gene
City
People Nucleotide
base pairs
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Section:
Figure 11-19 Gene Map of the Fruit Fly
Section 11-5
Exact location on chromosomes Chromosome 2
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Section:
Video 1
Meiosis Overview
Click the image to play the video segment.
Video 2
Animal Cell Meiosis, Part 1
Click the image to play the video segment.
Video 3
Animal Cell Meiosis, Part 2
Click the image to play the video segment.
Video 4
Segregation of Chromosomes
Click the image to play the video segment.
Video 5
Crossing Over
Click the image to play the video segment.
Interest Grabber Answers
1. In how many places can crossing over result in genes A and b being on the
same chromosome?
One (between A and B)
2. In how many places can crossing over result in genes A and c being on the
same chromosome? Genes A and e?
Two (between A and B and A and C); Four (between A and B, A and C, A
and D, and A and E)
3. How does the distance between two genes on a chromosome affect the
chances that crossing over will recombine those genes?
The farther apart the genes are, the more likely they are to be recombined
through crossing over.