Chapter 1 Summary

The topics covered in this chapter can be summarized as follows:

  • Mendel demonstrated that heredity involved discrete, heritable factors that affected specific traits.
  • A gene can be defined operationally as a unit of inheritance.
  • Homologous chromosomes contain the same series of genes along their length, but not necessarily the same alleles. Sister chromatids initially contain the same alleles.
  • Homologous chromosomes pair (synapse) with each other during meiosis, but not mitosis.
  • A diploid organism can have up to two different alleles at a single locus. The alleles segregate equally between gametes during meiosis.
  • Phenotype depends on the alleles that are present, their dominance relationships, and sometimes interactions with the environment and other factors.
  • Classical geneticists make use of true breeding lines, monohybrid crosses, Punnett squares, test crosses, and reciprocal crosses.


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Introduction to Genetics Copyright © 2023 by Natasha Ramroop Singh, Thompson Rivers University is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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