7.1 Inheritance

• What is meant by the term genotype?

  Genetic constitution of an organism
• What is meant by the term phenotype?


  The expression of this genetic constitution (genotype) and its interaction with the environment
• What are alleles and how do they arise?

  Variations of a particular gene (same locus) → arise by mutation (changes in DNA base sequence)
• How many alleles of a gene can be found in diploid organisms?

  ● 2 as diploid organisms have 2 sets of chromosomes (chromosomes are found in homologous pairs) ○ But there may be many (more than 2) alleles of a single gene in a population
• Describe the different types of alleles

  1. Dominant allele Always expressed (shown in the phenotype
  2. Recessive allele

  Only expressed 2 copies present (homozygous recessive) / not expressed when dominant allele present (heterozygous)

  1. Codominant alleles

  Both alleles expressed / contribute to phenotype (if inherited together)