4. Factors that affect individuality Theory of blending inheritance Traits manifested on ofsspring are a combination of the traits of the parents Heredity (nature) Environment (nurture)
5. Nature-Nurture Controversy “Which is a more important factor in how your personality develops – nature or nurture?” What are the different factors that affect individuality? How does heredity bring about traits in every individual? How does environment affect an individual’s traits?
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8. Objectives cite specific examples of each of the four types if hereditary characters explain inheritance based on Mendelian laws
9. Hereditary Characters Characters that are controlled by genes Genes factors of heredity transmitted from one generation to the next Which do you inherit from your parents?, the genes or the characters?
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11. Hereditary Characters Morphological Characters that refer to structure or form such as shape, length or color of body parts E.g. fur color in cats hitchhiker’s thumb bent little finger
13. Hereditary Characters Behavioral externally directed activities in response to stimuli examples are instincts such as crying and thumb sucking in babies
15. Classifying Hereditary Characters Classify the following and present your answer in tabulated form: Hitchhiker’s thumb 8.Internal and external genitalia Cleft chin 9. Spinning of spider’s web Bent little finger 10. Pubic hair Lactose intolerance 11. Diabetes mellitus Fur color in cats 12. Bird migration Widow’s peak 13. widening of hips in females Polydactyly 14. appearance of Adam’s apples
20. Mendel’s Experiments Gregor Johann Mendel – Father of Classical Genetics Austrian monk and a botanist Joined the Augustinian Monastery of St.Thomas at Brunn, Austria Spent 10 years in experimenting garden peas (Pisumsativum) Another 2 years in analyzing the results
21. Why garden peas? The plant has several characters that exhibit two contrasting expressions or traits. The plant reproduces at a fast rate. Garden peas can produce enough offspring for study purposes Garden pea flowers are structurally adapted for self-pollination Pollination can be controlled in this group of plants with minimum work
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24. Mendel’s Experimental Design Mendel studied one character with two contrasting expressions at a time, e.g. seed color, yellow and green. yellow-seeded plants self-pollination pure-breeding yellow-seeded plants green-seeded plants self-pollination pure-breeding green-seeded plants 2. Mendel cross-pollinated the two pure-breeding plants with contrasting expressions for the same character (seed shape used in the example.)
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26. Mendel’s Experimental Design 2. The parents were referred to as the first parental (P1) generation. The offspring produced from the cross is referred to as the first filial (F1) generation. Law of Dominance – some traits are transmitted to and manifested in offspring more often than others Dominant traits – traits that are expressed Recessive traits – traits that are hidden or not expressed
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28. Mendel’s Experimental Design 3. Mendel allowed the F1 plants to self-pollinate. He noted that some of the offspring expressed the recessive trait.
29. Two important observations: When the F1 plants that expressed only the domonant trait were self-pollinated, some of their offspring (f2) expressed the recessive trait. The ratio of the plants with dominant traits to the plants with recessive traits is almost 3:1
30. F1 plants have “unit determiners/characters” F1 plants with yellow seed color – two unit determiners: one for the yellow, one for the green seed color Mendel unit determiners Walter Sutton (1902) GENES
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34. Mendelian Principles of Inheritance Seed color G – yellow g – green :: G and g alleles (alternative/different forms of the gene for the seed color) :: genes appear in pairs :: yellow-seeded plants – GG :: green –seeded plants - gg
35. Phenotype – physical expression of the character Genotype – set of genes that an organism has Homozygous – gene pairs that are made up of identical genes Heterozygous – gene pairs that are made up of dissimilar genes
36. Seatwork: Identify if the following gene pairs are homozygous or heterozygous AA 6. SSrr Rr 7. GG aaBB 8. LLll MmNN 9. CCrr PpQq 10. Jj
