Genetic diagrams

• What do genetic diagrams show?

  Combinations of alleles from two parents
• What does the dominant allele 'A' code for in mice?

  Normal amounts of average muscle
• What does the recessive allele 'a' code for in mice?

  Increased muscular mass
• How are alleles represented in genetic diagrams?

  As uppercase and lowercase letters
• What does a homozygous normal mouse's genotype look like?

  Capital A, capital A
• What is the phenotype of a homozygous muscular mouse?

  Muscular
• How do you find the gametes from a parent's genotype?

  Split the letters into separate circles
• What do you do to find the offspring's genotypes?

  Combine the gametes from both parents
• What is the result when combining a capital A gamete and a lowercase a gamete?

  Capital A, lowercase a genotype
• What does it mean for offspring to be heterozygous?

  They have one allele of each type
• What phenotype do all heterozygous offspring have?

  Normal phenotype
• What is a Punnett square used for?

  To show genetic combinations visually
• How does a Punnett square differ from a genetic diagram?

  Punnett squares are simpler to draw
• What is the outcome ratio of normal to muscular mice from two heterozygous parents?

  3 to 1 ratio
• What is the genotype of the offspring when two heterozygous mice mate?

  One homozygous dominant, two heterozygous, one homozygous recessive
• What is the probability of having muscular offspring from two heterozygous parents?

  One in four or 25%
• What is the phenotype outcome when two heterozygous mice mate?

  Three normal and one muscular
• What are the five main steps to draw a genetic diagram?

  1. Identify parents' phenotype and genotype
  2. Determine gametes' genotypes
  3. Combine gametes to find offspring's genotypes
  4. Determine offspring's phenotypes
  5. Present results in a diagram
• How do genes and environment interact to affect traits?

  • Multiple genes influence traits
  • Environmental factors can modify expression
  • Example: Nutrition affects height
• What is the importance of the dominant allele in phenotypes?

  It determines the expressed trait
• Why is it important to consider multiple genes in traits?

  They interact to influence the phenotype
• What is the role of the environment in determining traits?

  It can influence gene expression
• What are family trees sometimes called?

  Family pedigrees
• What type of disorder is cystic fibrosis?

  Recessive inherited disorder
• What does it mean for cystic fibrosis to be recessive?

  You need two cystic fibrosis alleles to have it
• How are cystic fibrosis alleles represented?

  Lowercase f
• How is the healthy version of the cystic fibrosis allele represented?

  Uppercase F
• What genotype indicates a person has cystic fibrosis?

  Homozygous recessive genotype
• What genotype indicates a carrier of cystic fibrosis?

  Heterozygous genotype
• What does a homozygous dominant genotype indicate?

  No cystic fibrosis disease
• What do circles and squares represent in a family pedigree?

  Circles are females, squares are males
• What does a shaded shape indicate in a family pedigree?

  Person has the condition
• What do half-shaded shapes indicate in a family pedigree?

  Person is a carrier
• What should you look for in a family pedigree key?

  Explanation of symbols used
• How do you determine the genotype of individuals in a pedigree?

  By analyzing the diagram
• What does each new row in a family tree represent?

  A new generation
• What does a horizontal line connecting two shapes indicate?

  They are a couple
• What genotype does Jenny have in the family tree?

  Homozygous dominant genotype
• What genotype does Paul have in the family tree?

  Heterozygous genotype
• What genotypes do Anna and Lucy have?

  Heterozygous genotype