# Ch. 9 Fundamental Genetics Gregor Mendel  “Father of Genetics” He is famous for his pea plant studies. He taught high school math and was a monk. Mendel.

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Ch. 9 Fundamental Genetics Gregor Mendel  “Father of Genetics” He is famous for his pea plant studies. He taught high school math and was a monk. Mendel studied pea plants with pure traits, in which the plant always produces offspring with that specific traits. A pure trait is called a strain. Ex. TT is a strain for a tall pea plant.

Mendel’s Experiments 1. He studied the self-pollination strains of pea plants. He discovered 14 strains. (Picture) A strain is called the P1 (parental) Generation 2. Mendel then used cross-pollination. What is cross- pollination? He crossed P1 Generation plants These produced an F1 (first filial) Generation Ex. TT X tt plants  Tall plants Homozygous Tall X Homozygous Short  100% Tall

3. He then cross-pollinated the pea plants from the F1 Generation and collected the seeds. The offspring produced from this generation was called the F2 (second filial) Generation. Ex. Heterozygous Tall X Heterozygous Tall  ¾ Tall & ¼ Short. There are two alleles per trait. Ex. TT (both Ts are alleles)

Punnett Square R=round peas(dominate) & r=wrinkled peas(recessive). P1 Generation = strains (pure traits) RR= round (dominate strain) rr= wrinkled (recessive strain) F1 Generation = Always heterozygous dominate. F2 Generation = Always a 3 to 1 ratio.

Punnett Square R R rr Rr F1 Generation All Heterozygous (Rr) R r Rr RRRr rr F2 Generation 3:1 Ratio 3 tall : 1 short

Heredity What is heredity? The transmission of traits from parents to offspring. The receiving of traits is called inheritance. What is a gene? A segment of DNA on a chromosome that controls a particular hereditary trait. Ex. Blue eyes Video - genetics

Traits have at least two alleles on them. Lower case alleles are recessive. Upper case alleles are dominate. What are alike alleles called? Homozygous : RR(dominate) & rr(recessive) What are unlike alleles called? Heterozygous Three or more alleles are called multiple alleles.

Genotype is the type of genes an individual has. It is the genetic make up of an organism Ex. TT, Tt, or tt Phenotype is the external appearance of an organism. Ex. Tall or short

Probability is the likelihood for an event to occur. # of a specific event / # of all events 787 Tall plants / 1064 total plants =.739 Codominace occurs when 3 or more alleles influence the phenotype. (Draw on the board). Ex. R = red, R’ = white (P1 Generation) Cross and get all RR’ (F1 Generation) Cross and get RR, RR’, RR’, & R’R’ (F2 Generation) RR = red, RR’ = pink, & R’R’ = white VideoVideo – probability Dihybrid Crosses

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