Genetic Diagram

• What do genetic diagrams show?

  Combinations of alleles from 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?

  Muscular mass
• How are alleles represented in genetic diagrams?

  Uppercase for dominant, lowercase for recessive
• What is a typical question regarding genetic diagrams?

  Draw a genetic diagram for a cross
• 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 the results
• What is the genotype of a homozygous normal mouse?

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

  Muscular
• Why is the muscular allele expressed in a homozygous muscular mouse?

  Because it has two recessive alleles
• How do you find the gametes from a parent's genotype?

  Split the letters into separate circles
• What do you get when you combine a capital A gamete with 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
• How does a Punnett square work?

  • Create a 2x2 grid
  • Place one parent's gametes on top
  • Place the other parent's gametes on the left
  • Fill in the squares with combinations
• What is a downside of using Punnett squares?

  They don't show parents' or offspring's phenotypes
• What happens when two heterozygous normal mice mate?

  They produce one homozygous dominant and two heterozygous offspring
• What is the phenotypic ratio of offspring from two heterozygous normal mice?

  Three normal to one muscular
• What is the probability of having muscular offspring from two heterozygous normal mice?

  One in four or 25%
• What is the importance of multiple genes and environment in traits?

  • Multiple genes interact to determine traits
  • Environmental factors influence trait expression
  • Example: Nutrition affects height
• What should you do if you enjoyed the video?

  Like and subscribe
• 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?

  Two cystic fibrosis alleles are needed
• 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 person is a carrier of cystic fibrosis?

  Heterozygous genotype
• What genotype indicates a person is unaffected by cystic fibrosis?

  Homozygous dominant genotype
• What do circles represent in a family pedigree?

  Females
• What do squares represent in a family pedigree?

  Males
• What does a shaded shape indicate in a family pedigree?

  Person has the condition
• What does a half-shaded shape indicate in a family pedigree?

  Person is a carrier
• What should you be given with a family pedigree in an exam?

  A key explaining the symbols
• How do you determine the genotype of each person in a pedigree?

  Using the diagram and understanding inheritance
• 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 (capital F capital F)
• What genotype does Paul have in the family tree?

  Heterozygous (capital F lowercase f)
• What genotypes do Anna and Lucy have?

  Both are heterozygous (capital F lowercase f)
• What genotypes do Ron and Harry have?

  Both are homozygous dominant (capital F capital F)