3.7.1

• Dominant

  Only a single allele is required for the characteristic to be expressed, changing the phenotype.
• Recessive

  Characteristic is only expressed if there is no dominant allele present.
• Codominant

  Both alleles are expressed equally and contribute to the phenotype

  • Either a blend of the two or both seen together.
• Pure breeding

  Homozygous pair of alleles.
• Allele

  An alternative form of a gene
• Locus

  The specific position of the gene on the chromosome.

  • Alleles for a gene are both found at the same loci on homologous pairs of chromosomes.
• Monohybrid inheritance

  When a phenotype or trait is controlled by a single gene.
• Dihybrid inheritance

  Two characteristics are studied and is determined by two different genes that are present on two different chromosomes at the same time.
• Sex linkage

  The expression of an allele is dependent on the gender of the individual as the gene is located on a sex chromosome
• Autosome

  Any chromosome that isn’t a sex chromosome
• Autosomal linkage

  Two or more genes that are on the same autosomal chromosome.
• Epistasis

  The interaction of different loci on the gene;

  • One gene locus affects the other gene locus.
• One gene loci can either mask or suppress the expression of another gene locus.
• Genotype

  The genetic constitution of an organism
• Phenotype

  The expression of an organism‘s genetic constitution and its interaction with the environment
• Gene pool


  All the different alleles of all the different genes of all individuals of a population at a given time.