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Assignment # Mendel Loved His Peas!. Mrs. McCarthy Biology August 28, 2014. I. Gregor Mendel Father of Genetics Austrian Monk Published his work in 1866 Bred different varieties of garden pea , Pisum Sativum. 1. Garden Peas are good subjects because:
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Assignment #Mendel Loved His Peas! Mrs. McCarthy BiologyAugust 28, 2014
I. Gregor Mendel • Father of Genetics • Austrian Monk • Published his work in 1866 • Bred different varieties of garden pea, Pisum Sativum
1. Garden Peas are good subjects because: • They have many traits with two clearly different forms that are easy to tell apart • Mating can be easily controlled. (Self-pollinating or cross-pollinating) • They are small, grow easily, mature quickly and produce many offspring=QUICK RESULTS! • Don’t talk back to scientists.
E. First to develop rules that accurately predict patterns of heredity 1. Heredity- passing of traits fromparents to offspring 2. Genetics- branch of biology that focuses on heredity
II. Mendel’s Experiment • Step 1: He let the flowers self pollinate for several generations to get a true breeding variety • Step 2: He then cross pollinated two P generation (first individuals crossed) plants that had contrasting forms of the trait • F1 Generation- first filial generation (first babies…aww! How cute!) • Step 3: he then allowed the F1 generation to self pollinate • F2- second filial generation • RESULTS: He found a 3:1 ratio of plants expressing the contrasting traits in the F2 generation
III. Crossing • Monohybrid Cross- a cross that involves one pairof contrasting traits • Ex. Flower color, wrinkled peas vs. round peas, height • Dihybrid Cross- a cross that involves two pairsof contrasting traits • Ex. Flower color AND height • True Breeding- all the offspring would display only one form of a particular trait
D. Allele- different copies or forms of a gene controlling a certain trait Ex. T or t (Letters are used to represent alleles) E. Law of Segregation- two alleles for a trait separate when gametes are formed (in meiosis) F. Law of independent assortment- alleles of different genes separate independently of one another during gamete formation (also in meiosis)
IV. Dominant vs. Recessive A. Dominant- the trait that is expressed 1. Shown by a CAPITAL letter Ex. T B. Recessive- the trait that is not expressed (hidden) 1. Shown by lowercase letter Ex. t C. Genotype- genetic make up Ex. Tt or TT D. Phenotype- physical trait Ex. Short or Tall
E. Homozygous- two of the same alleles for that trait 1. Purebred Ex. TT or tt F. Heterozygous- two different alleles for that trait 1. Hybrid Ex. Tt
r R Y y G g t T
Tall Gg Heterozygous Yellow Seeds Homozygous RR Yellow pod Homozygous Round Seed
Homozygous tt Heterozygous Yy Tall rr Homozygous Green seed Green Pod Homozygous