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GENETICS

Learn how to use Punnett squares to make predictions about the possible genetic combinations and outcomes of inherited characteristics. Understand the rules of Punnett squares and how to interpret the results.

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GENETICS

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  1. T T Tt GENETICS t t PUNNETT SQUARE

  2. EXPECTATION Make predictions about possible outcomes of various genetic combinations of inherited characteristics.

  3. PUNNETT SQUARE RULES PARENT’SGENES A Punnett square is a tool used to predict the possible genotypes for the offspring of two known parents. PARENT’S GENES

  4. VOCABULARY

  5. PUNNETT SQUARE • The parent’s alleles go on the OUTSIDE of the square. R R RR X rr r r

  6. HOW TO USE A PUNNETT SQUARE 1. The parent’s alleles go on the OUTSIDE of the square. 2. DROP the letters on the top into each square. R R r Rr Rr NOTE: The ORDER DOES NOT matter in the boxes, but uppercase first is a good rule. r 3. MOVE each letter on the side into each square. Rr Rr

  7. HOW TO USE A PUNNETT SQUARE WHAT DO THE RESULTS SHOW? RESULTS: B B If B is the DOMINANTallele for BLACK PHENOTYPIC: 100% BLACK 4:0 RATIO, BLACK TO BROWN b Bb Bb And b is the RECESSIVE allele for BROWN GENOTYPIC: 100% Bb 4:0 ALL Bb b Bb Bb Then, we can make predictions about the outcomes.

  8. HOW TO USE A PUNNETT SQUARE LET’S LOOK AT ANOTHER PUNNETT SQUARE AND PREDICT THE OUTCOME. WHAT ARE THE RESULTS? T t PHENOTYPIC: 75% TALL 25% SHORT 3 : 1 RATIO: TALL TO SHORT Tt T is the DOMINANTallele for tallness. TT T t is the RECESSIVE allele for shortness. GENOTYPIC: 1TT: 2Tt: 1tt 1:2:1 RATIO 25 %TT, 50% Tt, 25% tt t tt Tt

  9. PUNNETT SQUARE PRACTICE Complete Punnett Square: • Yellow is dominant (Y). • Green is recessive (y). • Father - yy • Mother - Yy • Identify the phenotype and genotype. SeedColor

  10. PUNNETT SQUARES Set up the square. Complete PunnettSquare: SeedColor • Yellow is dominant (Y). • Green is recessive (y). • Father - yy • Mother - Yy • Phenotype – • Genotype –

  11. PUNNETT SQUARES KEY Complete Punnett Square: SeedColor • Yellow is dominant (Y) • Green is recessive (y) • Father - yy • Mother - Yy • Phenotype - 50% Yellow and 50% green f. Genotype - 50% Yy and 50% yy y Y y yy Yy y yy Yy

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