Genetic diagrams

• What are alleles?

  • Different versions of the same gene
  • Can be homozygous or heterozygous
• How many copies of each gene do most organisms have?

  Two copies, one from each parent
• What does it mean to be heterozygous for a gene?

  Having two different alleles for that particular gene
• What does it mean to be homozygous for a gene?

  Having two identical alleles for that particular gene
• What is the characteristic that appears when you are heterozygous for a trait?

  The characteristic caused by the dominant allele
• What is the difference between a dominant allele and a recessive allele?

  A dominant allele expresses its characteristic even when paired with a different allele, while a recessive allele only expresses its characteristic when both alleles are recessive
• How are alleles represented in genetic diagrams?

  Capital letters represent dominant alleles, and small letters represent recessive alleles
• What is an organism's genotype?

  The genes and alleles it has
• What is an organism's phenotype?


  The characteristics that it displays
• What is single gene inheritance?

  • Characteristics controlled by a single gene
  • Example: Blood groups
• How do genetic diagrams help in predicting offspring characteristics?

  They help predict the phenotypes of the offspring when the genotypes of the parents are known
• What happens when you breed two homozygous hamsters, one BB and one bb?

  All offspring will have a Bb genotype and a boring phenotype
• What is the difference between single gene inheritance and multiple gene inheritance?

  • Single gene inheritance: controlled by one gene (e.g., blood groups)
  • Multiple gene inheritance: controlled by multiple genes (e.g., height)
• What is the significance of the term "meanotype" in the context of sibling relationships?

  It determines how nice you are to your sibling
• What condition do people with albinism have?

  They lack pigment in their skin and eyes