Genes Come in Pairs

Mendel deduced that pure-bred parents have two copies of the same gene for each trait.

Rather than looking at the pea plant as a whole, Mendel focused on seven individual traits that he could readily distinguish. He found that each trait has two alternate forms. For example, seed color can be green or yellow. By analyzing the results of various crosses, Mendel concluded that each alternative form of a trait is specified by alternative forms of a gene.To follow the inheritance of genes from parent to child,Mendel first needed to be sure which genes each parent carried. Since pea plants are naturally self-fertilizing, "pure-bred" strains were readily available. Each strain contained only one form of the gene that determined a trait. Pure-bred plants with yellow seeds only produced offspring with yellow seeds. Pure-bred plants with green seeds only produced offspring with green seeds. From the results of further experiments, Mendel reasoned that pure-bred plants must have two copies of the same gene for each trait.

seed color, yellow seeds,green seeds, pea plants, alternate forms, genes, offspring, inheritance, strains, crosses, pairs, parents, pure-bred strains, self fertilizing

  • ID: 16153
  • Source: DNALC.DNAFTB

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16154. Genes Come in Pairs

DNAFTB Animation 2: Gregor Mendel explains how he discovered that genes come in pairs by studying pea plants.

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16182. Some genes are dominant.

DNAFTB Animation 4: Gregor Mendel explains the rules of inheritance.

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16169. Concept 3: Gene's don't blend.

Mendel discovered that pure-bred plants did not produce offspring with blended traits.

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16181. Some genes are dominant.

DNAFTB Concept 4: Mendel identifies dominant and recessive genes.

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16168. Problem 2: Genes come in pairs

Repeat Mendel's experiments with an eighth trait.

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16190. Some genes are dominant.

DNAFTB Problem 4: Cross pure-bred pea plants to identify dominant flower color.

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16207. Problem 5: Genetic inheritance follows rules.

Perform a dihybrid cross.

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16313. Problem 12: Evolution begins with the inheritance of gene variations.

DNAFTB Problem 12:Explore "hybrid vigor."

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16301. Evolution begins with the inheritance of gene variations.

Animation 12 George Shull used corn to study gene variation.

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16191. Concept 5: Genetic inheritance follows rules.

Different gene combinations result in different dominant/recessive ratios in offspring.

  • ID: 16153
  • Type: illustration
  • Source: DNAFTB