Inheritance

• What is a gene?


  A sequence of bases on a DNA molecule that codes for a protein.
• What does a gene code for?


  A protein (polypeptide) that results in a characteristic.
• What is an allele?


  A different version of a gene.
• How many alleles do most plants and animals have for each gene?


  Two alleles, one from each parent.
• How do the bases in different alleles compare?


  The order of bases in each allele is slightly different.
• How are alleles represented?


  Using letters, e.g., B for brown eyes and b for blue eyes.
• What is a genotype?


  The alleles an organism has, e.g., BB, Bb, or bb.
• What does the phenotype represent?


  The characteristics produced by the alleles.
• What is an example of a phenotype?


  Brown eyes.
• What is a dominant allele?


  An allele whose characteristic appears in the phenotype even with one copy.
• How is a dominant allele represented?


  By a capital letter.
• What is an example of a dominant allele?


  The allele for brown eyes (B).
• What is a recessive allele?


  An allele whose characteristic appears only if two copies are present.
• How is a recessive allele represented?


  By a lowercase letter.
• What is an example of a recessive allele?


  The allele for blue eyes (b).
• What are codominant alleles?


  Alleles that are both expressed in the phenotype.
• What is a locus?


  The fixed position of a gene on a chromosome.
• Where are alleles of a gene found?


  At the same locus on each chromosome in a pair.
• What is a homozygote?


  An organism that carries two copies of the same allele.
• What is an example of a homozygote?


  BB or bb.
• What is a heterozygote?


  An organism that carries two different alleles.
• What is an example of a heterozygote?


  Bb.
• What is a carrier?


  A person carrying an allele not expressed in the phenotype but can be passed to offspring.
• What are the key terms related to genetics covered in the study material?

  • Gene: Sequence of bases coding for a protein.
  • Allele: Different version of a gene.
  • Genotype: The alleles an organism has.
  • Phenotype: Characteristics produced by alleles.
  • Dominant: Allele expressed with one copy.
  • Recessive: Allele expressed with two copies.
  • Codominant: Both alleles expressed.
  • Locus: Fixed position of a gene on a chromosome.
  • Homozygote: Two copies of the same allele.
  • Heterozygote: Two different alleles.
  • Carrier: Person carrying an unexpressed allele.