genetic diagrams

• What do genetic diagrams show us?


  They show the different combinations of alleles from two parents.
• What does the dominant allele 'A' code for in the example of the mouse?


  It codes for normal amounts of average muscle.
• How is the recessive allele represented in the genetic diagram?


  It is represented as a lowercase letter.
• What is a typical question regarding genetic diagrams?


  Draw a genetic diagram for the cross between a homozygous normal mouse and a homozygous muscular mouse.
• What are the five main steps to draw a genetic diagram?


  1. Identify the parents' phenotype and genotype.
  2. Determine the gametes' genotypes.
  3. Combine the gametes to find offspring's genotypes.
  4. Determine the offspring's phenotypes.
  5. Present the results in a genetic diagram.
• What is the genotype of a homozygous normal mouse?


  Capital A, capital A.
• Why does the homozygous recessive allele express its phenotype?


  Because it is homozygous, meaning both alleles are recessive.
• How do you find the gametes from the parents' genotypes?


  You split the two letters in each parent's genotype into separate circles.
• What is the result of combining a capital A gamete with a lowercase a gamete?


  The genotype will be capital A, lowercase a.
• What does it mean for offspring to be heterozygous?


  It means they have one allele of each type.
• What phenotype do all heterozygous offspring have in this example?


  They all have the normal phenotype.
• How does a Punnett square work?


  • It is a grid used to predict the genotypes of offspring.
  • Place one parent's gametes at the top and the other on the left.
  • Fill in the squares based on the combinations of gametes.
• What is the outcome when two heterozygous normal mice mate?


  They produce one homozygous dominant, two heterozygous, and one homozygous recessive offspring.
• What is the phenotypic ratio of normal to muscular mice from the cross of two heterozygous normal mice?


  The ratio is 3:1 for normal to muscular mice.
• What is the probability of having muscular offspring from the cross of two heterozygous normal mice?


  There is a 25% probability of having muscular offspring.