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Punnett Squares

T. T. Tt. t. t. Punnett Squares. SINGLE TRAIT PUNNETT SQUARE. ¼. Genetics. Genetics is the study of genes and inheritance Inheritance is how traits are passed on from generation to generation. Chromosomes are made up of genes, which are made up of DNA. Gregor Mendel.

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Punnett Squares

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  1. T T Tt t t Punnett Squares SINGLE TRAIT PUNNETT SQUARE ¼

  2. Genetics • Genetics is the study of genes and inheritance • Inheritance is how traits are passed on from generation to generation. • Chromosomes are made up of genes, which are made up of DNA.

  3. Gregor Mendel • Austrian monk • Experimented with pea plants • He discovered that traits were carried from one generation to the next.

  4. TERMS TO KNOW

  5. TERMS TO KNOW

  6. TERMS TO KNOW

  7. Mendel’s Experiment He chose to work with pea plants because • Readily available • Reproduced quickly • Traits were distinct

  8. Mendel’s Experiment Mendel crossed true breeding plants that had two distinct and contrasting traits, like purple and white flowers. After the first cross, the plants self-fertilized.

  9. Mendel’s Experiment P generation is parental generation. F1 generation is the first generation. F2 generation is the second generation.

  10. Mendel’s Experiment He studied these seven traits

  11. Mendel’s Phenotypic Conclusions In the F1 generation, all plants had the same trait. In the F2 generation, there was always a 3:1 ratio of a single trait.

  12. Mendel’s Genotypic Conclusions In the F2 generation, The genotypic ratiois different. Remember P is dominant so the plants will be purple even with Pp.

  13. TOOLS TO KNOW PARENT’SGENES A PUNNET SQUARE IS A TOOL USED TO PREDICT THE POSSIBLE GENOTYPES FOR THE OFFSPRING OF TWO KNOWN PARENTS. PARENT’S GENES

  14. HOW TO USE A MONOHYBRID (ONE TRAIT) PUNNETT SQUARE THE PARENTS’ ALLELES GO ON THE OUTSIDE OF THE SQUARE B B BB X bb b b

  15. HOW TO USE A MONOHYBRID (ONE TRAIT) PUNNETT SQUARE THE PARENTS’ ALLELES GO ON THE OUTSIDE OF THE SQUARE B B b B b B b b UPPERCASELETTERS SHOULDGO FIRST B b B b

  16. HOW TO USE A MONOHYBRID (ONE TRAIT) PUNNETT SQUARE WHAT DO THE RESULTS SHOW? B B B IS THE DOMINANT ALLELE FOR BLACK b Bb Bb RESULTS: b IS THE RECESSIVE ALLELE FOR BROWN Bb Bb Bb Bb b PHENOTYPIC:100% BLACK 4:0 RATIO, BLACK TO BROWN Bb Bb GENOTYPIC: 100% Bb 4:0 ALL Bb

  17. HOW TO USE A PUNNETT SQUARE LET’S LOOK AT ANOTHER PUNNETT SQUARE AND PREDICT THE OUTCOME T t T RESULTS: TT, Tt, Tt, tt T T T t T IS THE DOMINANT ALLELE FOR TALLNESS PHENOTYPIC: 75% TALL 25% SHORT 3 TO 1 RATIO: TALL TO SHORT t T t t t t IS THE RECESSIVE ALLELE FOR SHORTNESS GENOTYPIC: 1TT: 2Tt: 1tt 1:2:1 RATIO 25 %TT, 50% Tt, 25% tt

  18. Probability and Punnett Squares

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