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Development of genetics: Mendel and later

Inheritance, variation and evolution • The development of understanding of genetics and evolution

Key concepts

What you'll likely be quizzed about

  • Mendel studied seven discrete characteristics of Pisum sativum (pea) plants using true-breeding lines and controlled crosses.
  • His experiments showed that crosses between contrasting traits produced uniform F1 offspring and predictable ratios in the F2 generation, revealing consistent patterns of inheritance.
  • Mendel formulated the rules now known as Mendelian inheritance: dominant and recessive phenotypes, segregation of alleles during gamete formation, and independent assortment of different gene pairs when located on different chromosomes.
  • Although Mendel published these findings in 1866, contemporary acceptance was limited because blended inheritance remained the prevailing view.

Flashcards

Test your knowledge with interactive flashcards

What is an example of a recessive inherited disorder?

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Cystic fibrosis is a recessive genetic disorder caused by two copies of a recessive allele.

Key notes

Important points to keep in mind

Mendel uses true-breeding pea plants and records discrete trait ratios.

Dominant alleles mask recessive alleles in heterozygotes.

Segregation explains how alleles separate into gametes.

Independent assortment applies to genes on different chromosomes.

Genes are sections of DNA on chromosomes that code for proteins.

DNA consists of four bases with specific base-pairing rules (A–T, C–G).

Mendel publishes in 1866 and his work is rediscovered around 1900.

Chromosome observations provide a physical basis for Mendel’s factors.

The Human Genome Project produces reference sequences and aids gene discovery.

Antibiotic resistance exemplifies modern selection on genetic variation.

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