Genetics

• What is an allele?

  Alternate forms of a gene
• What is a dominant allele?

  The allele that will mask the effect of a recessive allele
• What is a recessive allele?

  The allele that is masked by the effect of a dominant allele
• What does genotype refer to?

  Genetic information carried by an individual
• What does phenotype refer to?

  Observable characteristics of the individual
• What is a Punnett square used for?

  The method used to determine % genotypes and phenotypes of a particular cross
• What is a gene?

  A section of DNA that codes for a protein
• How do proteins formed by genes affect individuals?

  They result in different traits being expressed in individuals
• What are some traits controlled by genes?

  Height, eye colour, and tongue rolling ability
• What happens if one parent has brown eyes and the other has blue eyes?

  The child may inherit either brown or blue eyes depending on the alleles
• What does it mean for an allele to be dominant?

  It masks the effect of a recessive allele
• How are dominant alleles represented in writing?

  With capital letters
• How are recessive alleles represented in writing?

  With lowercase letters
• What is the genotype if an individual has two dominant alleles?

  BB
• What is the genotype if an individual has two recessive alleles?

  bb
• What is the genotype if an individual has one dominant and one recessive allele?

  Bb
• What are the genotypes that can result from inheriting alleles from parents?

  BB, Bb, and bb
• What is the relationship between genotypes and phenotypes?

  Genotypes determine the phenotypes expressed
• What does it mean for an individual to be homozygous?

  They have two identical alleles
• What does it mean for an individual to be heterozygous?

  They have two different alleles
• What is the genotype for homozygous dominant?

  BB
• What is a pedigree?


  A pedigree is like a family tree.
• What is the genotype for homozygous recessive?

  bb
• What does a pedigree show?

  It shows which members of the family have the trait in question.
• What is the genotype for heterozygous?

  Bb
• What is a purebred organism?

  An organism that is homozygous
• How can you determine the pattern of inheritance using a pedigree?

  By analyzing the pedigree, you can determine if the trait is dominant, recessive, or sex-linked.
• What is a hybrid organism?

  An organism that is heterozygous
• How can you calculate the percentage genotypes and phenotypes using a Punnett square?

  • Create a grid for the alleles of each parent
  • Fill in the grid to show possible combinations
  • Calculate the percentage of each genotype and phenotype
• What do circles and squares represent in a pedigree?

  Circles represent females and squares represent males.
• If a man who is heterozygous for brown eyes marries a woman who is also heterozygous for brown eyes, what are the potential genotypes of their children?

  1 in 4 will be BB, 2 in 4 will be Bb, and 1 in 4 will be bb
• What are the potential phenotypes of the children from a heterozygous brown-eyed couple?

  3 in 4 will have brown eyes and 1 in 4 will have blue eyes
• What does a colored symbol in a pedigree indicate?

  A colored symbol indicates that the individual is affected with the trait.
• How are children represented in a pedigree?

  Children of a marriage are drawn in birth order below their parents.
• What are the key steps to using a Punnett square for genetic crosses?

  1. Identify the alleles of each parent
  2. Set up the Punnett square grid
  3. Fill in the grid with possible allele combinations
  4. Determine the genotypic and phenotypic ratios
• How are generations labeled in a pedigree?

  Generations are written in Roman numerals.
• How are individuals labeled in a pedigree?

  Individuals are labeled with Arabic numbers.
• How would you label an individual in the second generation who is the third child?

  II3
• What does it mean if all colored circles and squares in a pedigree represent an autosomal recessive trait?

  All colored circles and squares would be 'aa', while all white would be either 'AA' or 'Aa'.
• What can you conclude if individuals 8 and 9 produced a child with the trait that has "skipped a generation"?

  This can only happen if the trait is recessive, meaning both 8 and 9 must be heterozygous.