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Published byNigel Underwood Modified over 9 years ago
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Intro to Genetics
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Human Traits How do we get our traits? Why are we tall, short, blonde? What makes us us?
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Genetics Every living thing – plant or animal, microbe or human being – has a set of characteristics inherited from its parent or parents. Since the beginning of recorded history, people have wanted to understand how inheritance is passed from generation to generation
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What is Genetics? Genetics - the branch of biology that studies heredity Heredity - the passing on of traits from parents to offspring Traits - Characteristics that are inherited
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Mendelian Genetics Gregor Mendel, an Austrian monk, made important discoveries about inherited traits Mendel was born in 1822 in what is now the Czech republic He studied to be a priest and spent several years studying science and math
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Mendel Mendel spent the 14 years of his life working in the local monastery and teaching high school While there, Mendel was in charge of gardening and spent most of his time tending to and studying the plants around him
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Observations Mendel observed seven traits that are easily recognized and only occur in two forms Flower color: purple or white Flower position: axil or terminal Seed color: yellow or green Seed shape: round or wrinkled Pod shape: inflated or constricted Pod color: yellow or green Stem length: long or short
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Why these traits? Were these genetic or environmental factors?
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Experiments Mendel performed experiments with pea plants by forcing plants with different traits to pollinate each other The experiments are called genetic crosses
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Offspring Mendel noticed that many times the second generation plants showed different traits from the parents
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Pea Plants Pea plants reproduce sexually, meaning they have both male and female sex cells Gamete cell= sex cell. half of the chromosomes Somatic cell= the rest of the cells in your body. full set of chromosomes
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Offspring Phenotype = the physical characteristics of an organism. Ex. Blue eyes or brown eyes. Genotype = the gene combination of an organism that determines its phenotype.
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Alleles Alleles = the gene form for each variation of a trait. (Written as capital or lower case letter ex. B or b ) Dominant = the observable trait that masks a recessive form of a trait. (Written as a capital letter) Recessive = a hidden trait that is masked by a dominant trait but carried in the genes (Written as a lower case letter)
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Alleles Homozygous= when the two alleles for a trait are the same. Ex. BB or bb Heterozygous= when the two alleles for a trait are not the same. Ex. Bb
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Chromosome – gene – allele - trait
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