This document provides an introduction and review of genetics concepts. It discusses Gregor Mendel's work with pea plants and the inheritance of traits. Key terms like genotype, phenotype, dominant, recessive, and Punnett squares are defined. Students are given practice problems involving Punnett squares and homework assignments involving genetics worksheets.
5. Definitions: trait: a characteristic that can be passed from parent to offspring heredity: the passing of traits from parents to offspring genetics: the study of heredity
6. Allele: a form of a gene Dominant: allele that is expressed (regardless of its counterpart allele); represented by a capital letter (e.g. T) Recessive: allele that is expressed only when its counterpart allele is also recessive ; represented by a small letter (e.g. t) Examples of traits in pea plants
7. GENOTYPE AND PHENOTYPE Genotype: the combination of alleles for a trait e.g. TT, Tt, tt Phenotype: the physical feature resulting from a genotype e.g. tall, short
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9. Practice time! Fill in the chart on the next page with the correct genotype and phenotype for the pea plant traits. TRAIT DOMINANT RECESSIVE P A Y R p a y r
14. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). R r r r
15. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). What percentage of the offspring will be round? 50% R r r r Rr rr Rr rr
16. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). R r R r
17. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). What percentage of the offspring will be round? 75% R r R r RR Rr Rr rr
18. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). R R R r
19. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). What percentage of the offspring will be round? 100% R R R r RR RR Rr Rr
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21. INCOMPLETE DOMINANCE Neither the red gene (R) nor the white gene (W) is dominant. When the 2 genes are present in the same plant, a pink flower results. Both R and W are used (capital letters) because neither the red gene nor the white gene is dominant over the other. White Red
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