Alleles

• What should you be able to describe by the end of the video?

  Dominant and recessive alleles
• What do dominant alleles do in a phenotype?

  They show even with one copy present
• What is the definition of homozygous?

  Having two identical alleles for a trait
• What is the definition of heterozygous?

  Having two different alleles for a trait
• What is a genotype?

  The allele combination present in an organism
• What is a phenotype?

  The observable characteristics of an organism
• How many pairs of chromosomes do normal human cells contain?

  23 pairs
• Where does one chromosome in a pair come from?

  From the father
• What are alleles?

  Versions of a gene
• What does the allele for wet earwax symbolize?

  Capital E
• What does the allele for dry earwax symbolize?

  Lowercase e
• What is the genotype for a person with two copies of dry earwax?

  Lowercase e lowercase e
• What is the phenotype for a person with two alleles for dry earwax?

  Dry earwax
• What is the genotype for a person with two copies of wet earwax?

  Capital E capital E
• What is the phenotype for a person with two alleles for wet earwax?

  Wet earwax
• What is the genotype for a person with one allele for wet earwax and one for dry earwax?

  Capital E lowercase e
• What does it mean if a person is heterozygous for earwax alleles?

  They have two different alleles
• What phenotype does a heterozygous person for earwax have?

  Wet earwax
• What is a recessive allele?

  Shows only if two copies are present
• What is a dominant allele?

  Shows in the phenotype with one copy
• What is the relationship between genes and characteristics?

  Most characteristics are controlled by many genes
• What are the key definitions related to alleles and genotypes?

  • Dominant allele: Shows in phenotype with one copy
  • Recessive allele: Shows only with two copies
  • Homozygous: Two identical alleles
  • Heterozygous: Two different alleles
  • Genotype: Allele combination present
  • Phenotype: Observable characteristics
• What will the next video cover?

  Genetic crosses and allele inheritance
• Where can students find questions on this topic?

  In the vision workbook