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Chapter 11 Notes

Chapter 11 Notes. Introduction to Genetics. Genetics – Study of heredity Heredity – How things or characteristics (traits) are passed on from parent to offspring. Gregor Mendel ( 1822-1884 ). 1. “Father of Genetics” 2. Austrian Monk in the 1800’s – worked with pea plants

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Chapter 11 Notes

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  1. Chapter 11 Notes Introduction to Genetics

  2. Genetics – Study of heredity • Heredity – How things or characteristics (traits) are passed on from parent to offspring

  3. Gregor Mendel ( 1822-1884 ) 1. “Father of Genetics” 2. Austrian Monk in the 1800’s – worked with pea plants 3. Why garden peas? - Reproduced by self-pollination - Have seven different traits (ex. Tall vs. short, round vs. wrinkled) 4. His experiments led to 4 Laws

  4. Fundamental Laws of Heredity • Law of Unit Characters • Traits are controlled by factors called genes • For every trait you have 2 genes • 1 from each parent • Law of Dominance • One of the gene pair can mask the other • The gene which appears or does the masking is called the dominant gene • The gene being masked is called recessive

  5. Law of Segregation - During the formation of gametes (meiosis) each gamete only receives one gene from the pair. (The chromatids separate and go to separate cells) • Law of Independent Assortment - Chance is involved in determining which gene a gamete will receive

  6. Genetic Terms and Abbreviations: Dominant Gene – (the masker) - Symbolized by a capital letter Recessive Gene – (the masked) - Symbolized by a small letter Homozygous – Alleles/genes are the same - Purebred  (TT, tt) Heterozygous – Alleles/genes are different - Hybrid  (Tt)

  7. Genotype – The genetic make-up of an individual -Letters (TT, Tt, tt) • Phenotype– The individuals physical appearance - Words (tall, short, straight hair, green eyes, etc.) • Punnett Square – Resembles a checker board and shows the possiblegene combinations of offspring

  8. Abbreviations and Generations P1 – Pure breeding parent generation F1 – (1st Fillial) Offspring generation; cross between members of the P generation F2 – (2nd Fillial) Offspring of crosses between members of F1 generation

  9. Ratios for MONOHYBRID CROSSES Phenotypic Ratio –Shows the ratio of physical traits How many dominant : How many recessive Ex. 3 Tall : 1 Short Genotypic Ratio– Shows the ratio of different genotypes Homozygous dominant: Heterozygous dominant: Homozygous recessive Ex. 1TT : 2Tt : 1tt

  10. Example Monohybrid Cross • In humans, being a tongue roller (R) is dominant over non-roller (r). A man who is a non-roller marries a woman who is heterozygous for tongue rolling. Father’s phenotype _____ Mother’s phenotype _____ Father’s genotype _____ Mother’s genotype _____ What is the probability of this couple having a child who is a tongue roller? ________

  11. Example Monohybrid Cross • In humans, being a tongue roller (R) is dominant over non-roller (r). A man who is a non-roller marries a woman who is heterozygous for tongue rolling. Father’s phenotype :non-roller Mother’s phenotype: roller Father’s genotype : rr Mother’s genotype : Rr R r r r What is the probability of this couple having a child who is a tongue roller? 2/4 = 50%

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