Genetics
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Transcript of Genetics
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Genetics
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Work of Gregor Mendel
• Genetics is the scientific study of heredity.• Gregor Mendel was an Austrian monk. His
work was important to the understanding of heredity.
• Mendel carried out his work with ordinary garden peas.
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Work of Gregor Mendel
• Mendel knew that – the male part of
each flower produces pollen, (containing sperm).
– the female part of the flower produces egg cells.
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Work of Gregor Mendel
• During sexual reproduction, sperm and egg cells join in a process called fertilization.
• Fertilization produces a new cell.
• Pea flowers are self-pollinating.
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Work of Gregor Mendel
• Mendel had true-breeding pea plants that, if allowed to self-pollinate, would produce offspring identical to themselves.
Cross-pollination
Mendel was able to produce seeds that had two different parents.
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Work of Gregor Mendel
• Genes and Dominance– A trait is a specific characteristic that varies from one
individual to another.
• Mendel studied seven pea plant traits, each with two contrasting characters.
• He crossed plants with each of the seven contrasting characters and studied their offspring.
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• Each original pair of plants is the P (parental) generation.
• The offspring are called the F1, or “first filial,” generation.
• The offspring of crosses between parents with different traits are called hybrids.
Mendel’s F1 Crosses on Pea Plants
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Work of Gregor Mendel
• Mendel's first conclusion – biological inheritance is determined by factors
that are passed from one generation to the next
• Today, scientists call the factors that determine traits genes.
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Work of Gregor Mendel
• Each of the traits Mendel studied was controlled by one gene that occurred in two contrasting forms that produced different characters for each trait.– The different forms of a gene are called alleles.
• Mendel’s second conclusion – principle of dominance– some alleles are dominant and others are recessive
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Work of Gregor Mendel
• Segregation– Mendel crossed the F1
generation with itself to produce the F2 (second filial) generation.
– The traits controlled by recessive alleles reappeared in one fourth of the F2 plants.
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Work of Gregor Mendel
• The reappearance of the trait controlled by the recessive allele indicated that at some point the allele for shortness had been separated, or segregated, from the allele for tallness.
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Work of Gregor Mendel
• Mendel suggested that the alleles for tallness and shortness in the F1 plants segregated from each other during the formation of the sex cells, or gametes.
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Knowledge Check
With which organism did Mendel work?
What is meant by self-pollinating?
What is cross pollination?
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Knowledge Check
What are genes?
What are alleles?
What is the principle of dominance?
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Knowledge Check
What is meant by segregation?
What are gametes?
When have we discussed gametes before?