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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.
Go to
Section:
Go to
Section:
Flower Parts
Go to
Section:
Principles of Dominance
Section 11-1
P Generation
Tall
Go to
Section:
Short
F1 Generation
Tall
Tall
F2 Generation
Tall
Tall
Tall
Short
Principles of Dominance
Section 11-1
P Generation
Tall
Go to
Section:
Short
F1 Generation
Tall
Tall
F2 Generation
Tall
Tall
Tall
Short
Principles of Dominance
Section 11-1
P Generation
Tall
Go to
Section:
Short
F1 Generation
Tall
Tall
F2 Generation
Tall
Tall
Tall
Short
Figure 11-3 Mendel’s Seven F1 Crosses
on Pea Plants
Section 11-1
Seed Coat
Color
Pod
Shape
Pod
Color
Smooth
Green
Seed
Shape
Seed
Color
Round
Yellow
Gray
Wrinkled
Green
White
Constricted
Round
Yellow
Gray
Smooth
Go to
Section:
Flower
Position
Plant
Height
Axial
Tall
Yellow
Terminal
Short
Green
Axial
Tall
Section Outline
Section 11-2
11–2
Probability and Punnett Squares
A.
B.
C.
D.
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Section:
Genetics and Probability
Punnett Squares
Probability and Segregation
Probabilities Predict Averages
Tt X Tt Monohybrid Cross
Section 11-2
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Section:
Tt X Tt Cross
Section 11-2
Go to
Section:
Monohybrid
Cross
Phenotypes
Go to
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
concluded
that
experimented
with
Pea
plants
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Section:
“Factors”
determine
traits
Some alleles
dominant,
& some alleles
recessive
Alleles are
separated during
gamete formation
which is
called the
which is
called the
Law of
Dominance
Law of
Segregation
Figure 11-10 Independent Assortment in Peas
Section 11-3
Go to
Section:
Dihybrid Cross
Section 11-2
Go to
Section:
Figure 11-11 Incomplete Dominance in
Four O’Clock Flowers
Section 11-3
Go to
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
Go to
Section:
Homologous
Chromosome
Go to
Section:
Crossing-Over
Section 11-4
Go to
Section:
Crossing-Over
Section 11-4
Go to
Section:
Crossing-Over
Section 11-4
Go to
Section:
Go to
Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
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Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
Go to
Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
Go to
Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
Go to
Section:
Figure 11-15 Meiosis
Section 11-4
Meiosis I
Go to
Section:
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II
Metaphase II
Anaphase II
Meiosis I results in two
The chromosomes line up in a The sister chromatids
haploid (N) daughter cells,
similar way to the metaphase separate and move toward
each with half the number of stage of mitosis.
opposite ends of the cell.
chromosomes as the original.
Go to
Section:
Telophase II
Meiosis II results in four
haploid (N) daughter cells.
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II
Metaphase II
Anaphase II
Meiosis I results in two
The chromosomes line up in a The sister chromatids
haploid (N) daughter cells,
similar way to the metaphase separate and move toward
each with half the number of stage of mitosis.
opposite ends of the cell.
chromosomes as the original.
Go to
Section:
Telophase II
Meiosis II results in four
haploid (N) daughter cells.
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II
Metaphase II
Anaphase II
Meiosis I results in two
The chromosomes line up in a The sister chromatids
haploid (N) daughter cells,
similar way to the metaphase separate and move toward
each with half the number of stage of mitosis.
opposite ends of the cell.
chromosomes as the original.
Go to
Section:
Telophase II
Meiosis II results in four
haploid (N) daughter cells.
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II
Metaphase II
Anaphase II
Meiosis I results in two
The chromosomes line up in a The sister chromatids
haploid (N) daughter cells,
similar way to the metaphase separate and move toward
each with half the number of stage of mitosis.
opposite ends of the cell.
chromosomes as the original.
Go to
Section:
Telophase II
Meiosis II results in four
haploid (N) daughter cells.
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II
Metaphase II
Anaphase II
Meiosis I results in two
The chromosomes line up in a The sister chromatids
haploid (N) daughter cells,
similar way to the metaphase separate and move toward
each with half the number of stage of mitosis.
opposite ends of the cell.
chromosomes as the original.
Go to
Section:
Telophase II
Meiosis II results in four
haploid (N) daughter cells.
Genetic Recombination
Go to
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.
Go to
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?
Go to
Section:
Section Outline
Section 11-5
11–5
Linkage and Gene Maps
A. Gene Linkage
B. Gene Maps
Go to
Section:
Comparative Scale of a Gene Map
Section 11-5
Mapping of Earth’s
Features
Mapping of Cells,
Chromosomes, and Genes
Cell
Earth
Country
Chromosome
State
Chromosome
fragment
City
People
Go to
Section:
Gene
Nucleotide
base pairs
Figure 11-19 Gene Map of the Fruit Fly
Section 11-5
Exact location on chromosomes
Go to
Section:
Chromosome 2
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.