Mendel’s Laws of Heredity Chapter 10.1 Mendel’s Laws of Heredity

Explain fertilization. Fertilization = male gamete (sperm) + female gamete (egg) Resulting cell is now called a zygote In plants, its called pollination Self-pollination = one plant Cross-pollination = two plants www.scienceclarified.com/.../uesc_05_img0247.jpg

Compare and contrast phenotype and genotype Phenotype = physical expression of genes Ex: Brown hair vs blonde hair Genotype = actual gene combination Ex: BB, Bb, bb Homozygous = BB (dominant), bb (recessive) Heterozygous = Bb

Phenotypes Genotypes

Punnett squares. Parent’s alleles go on side and top Carry alleles across or down Monohybrid Cross = one trait Dihybrid Cross = two traits

Why is Mendel the “Father of Genetics”? Mendel studied heredity of traits among pea plants Study of heredity = genetics He came up with the basic laws and understanding of genetics mendel.imp.ac.at/mendeljsp/images/mendel2.jpg

Explain the results of Mendel’s Monohybrid Cross. Some terms True breeding = many generations carrying the same trait P = parent F = filial (son or daughter)

Explain the results of Mendel’s Monohybrid Cross. Mendel’s cross pollination TALL plant x short plant (P1 generation) Result: Hybrids ALL offspring TALL (F1 generation) Self pollination of F1 F1 TALL X self (TALL) Result 3/4 TALL and 1/4 short (F2 generation) We refer to this as a ratio of 3:1

Mendel continued to test this with each of 7 traits Mendel continued to test this with each of 7 traits. Every time the same ratios appeared… Conclusion: Each organism has 2 factors (genes) that control each of its traits. Different versions of each factor (gene) is now called an allele Ex. Gene for height has a tall and short allele

Describe dominant and recessive alleles. Rule of dominance: in F1 generations the trait that is observed in 100% of the offspring is considered to be the dominant allele. Dominant alleles (TALL) mask the other form Recessive alleles (short) get masked by the dominant form ONLY ONE dominant allele is needed for the form to be expressed! Tt = TALL

Dom. alleles are always written first Dom. alleles are always given a capital letter, recessive get the lower case letter EX: for Height TALL = T or H or Z Short = t or h or z

Describe Mendel’s Law of Segregation. Every individual has 2 alleles for each gene Gametes are produced to carry only 1 from you parents When fertilization occurs you now have 2 alleles, 1 from mom, 1 from dad. 4 possible combinations ghs.gresham.k12.or.us/.../lawofsegregation.gif

Explain the results of Mendel’s Dihybrid Cross. P1: Round, Yellow x Wrinkled, Green RRYY x rryy F1: 100% Round, Yellow (dihybrids) F2: 9 Round, Yellow: 3 Round, Green : 3 Wrinkled, Yellow : 1 Wrinkled, Green

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Describe Mendel’s Law of Independent Assortment. Genes of different traits are inherited independently when found on different C. Ex: Not all Blondes have blue eyes

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