Mendel’s Laws of Heredity Chapter 10.1 (This might take 2 days)

Who was Gregor Mendel? Austrian monk Carried out studies on heredity using pea plants Studied the traits of pea plants that were passed on “Father of Genetics”

Gregor Mendel Sketch

II. Mendel Chose His Subject Carefully Plants reproduce asexually –Have both male and female reproductive organs –Both produce gametes Male/female sex cells Like sperm and egg –Fertilization –Zygote: the cell created by fertilization

II. Mendel Chose His Subject Carefully Pollination: transfer of pollen (plant sex cell) between plants Cross pollination: transfer of pollen between two different plants

Learn Gregor Mendel

Gregor Mendel: My Favorite Scientist

III. Mendel’s Monohybrid Cross Mono: one trait studied –Height (tall or short) Hybrid: contains different traits from parents who are purebred took tall pea plant, crossed with short pea plant –All offspring were tall (1 st generation) –Tall is dominant

III. Mendel’s Monohybrid Cross Took offspring and allowed it to “self- pollinate” –Took seeds from that plant –Planted them ¾ grew to be tall (dominant) ¼ grew to be short (recessive)

III. Mendel’s Monohybrid Cross

Mendel’s Laws of Heredity

A. The first generation The generation created by the parents (“P 1 ”) –Hybrids (Tt) Are called the “F 1 ” generation All were tall 4 out of 4 showed dominant trait

B. The second generation Created when 1 hybrid (1 F1 offspring) is allowed to self-pollinate Collect and plant seeds ¾ would be tall (75%) ¼ would be short (25%)

1 st and 2 nd Generations

Related to Real Life Your parents are the P 1 You are the F 1 Your children will be the F 2

IV. What you Learn from Mendel’s Work The “Rule of unit factors” The “Rule of dominance” The “Law of Segregation”

IV. What you Learn from Mendel’s Work A. The Rule of Unit Factors 2 factors control traits alleles: genetic letters –T, t –Every “trait” represented by 2 alleles

The Rule of Unit Factors

IV. What you Learn from Mendel’s Work B. The Rule of Dominance In the hybrid’s case (Tt) –Dominance: Tall trait (T) –Recessive: hidden trait (t) Dominant trait is the one you always see in most organisms (people)

Mendel’s Rule of Dominance

IV. What you Learn from Mendel’s Work C. The Law of Segregation Parents alleles must separate when donating an allele to an offspring Only donate “half” their genetic material Segregate: to split, to separate

Law of Segregation

V. Phenotypes and Genotypes Phenotype: the physical appearance –TT would be TALL –Tt would be TALL –tt would be SHORT

V. Phenotypes and Genotypes Genotype: the combination of alleles that represent a gene or trait –TT, Tt, or tt Homozygous = “same” –Homozygous dominant = TT –Homozygous recessive = tt Heterozygous = “different” –Heterozygous = Tt

Genotype vs. Phenotype

VI. Punnett Squares Used to predict probability that an offspring will show a certain trait Uses organisms genotypes Usually gives a percentage –0% –25% –50% –75% –100%

Punnett Square

How to Draw A Punnett Square

What are Punnett Squares