Genetic Diagrams

• What is the purpose of genetic diagrams?

  To illustrate inheritance patterns of traits
• What controls the characteristics you develop?

  Your inherited genes
• How many genes control size as a characteristic?

  One gene
• How are most characteristics controlled?

  By several genes acting together
• What are different versions of genes called?

  Alleles
• How many alleles do you have for every gene?

  Two alleles
• What does it mean if an organism is heterozygous?

  It has two different alleles for a gene
• What is a dominant allele?

  The allele that determines the characteristic shown
• How is a recessive allele represented?

  With a lowercase letter
• What must be true for an organism to display a recessive characteristic?

  Both alleles must be recessive
• What is the genotype of an organism?

  The combination of alleles it has
• What is the phenotype of an organism?

  The observable characteristics it displays
• What is the genotype of a superpowered hamster?

  bb
• What is the phenotype of a normal hamster?

  Normal (boring) behavior
• What happens when you breed two homozygous hamsters?

  All offspring are normal
• What is the ratio of normal to superpowered offspring from the first generation?

  3:1
• What is the probability of superpowers in the offspring?

  25%
• What is the expected ratio when crossing a heterozygous and a homozygous recessive cat?

  1:1 ratio
• What does a family tree help interpret?

  Inheritance patterns of traits
• What does the allele for cystic fibrosis indicate?

  It is recessive
• What is the chance of a new baby having cystic fibrosis if both parents are carriers?

  25%
• What is the expected outcome of a cross between a heterozygous pea plant and a homozygous recessive pea plant?

  Ratio of round to wrinkly peas
• What does a Punnett square show?

  Possible allele combinations of offspring
• What is the expected ratio of plants with round peas to plants with wrinkly peas in the pea plant cross?

  1:1 ratio
• What are the steps to create a genetic diagram?

  1. Identify the traits and alleles involved
  2. Determine the genotypes of the parents
  3. Create a Punnett square
  4. Calculate the offspring's genotypes and phenotypes
  5. State the ratio of phenotypes
• What are the key features of a family tree in genetics?

  • Shows inheritance patterns
  • Indicates affected and unaffected individuals
  • Helps identify carriers of recessive alleles
• What are the characteristics of dominant and recessive alleles?

  • Dominant alleles:
  • Represented by uppercase letters
  • Override recessive alleles
  • Recessive alleles:
  • Represented by lowercase letters
  • Only expressed when both alleles are recessive