Alleles

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

  Dominant and recessive alleles
• What are the terms you should learn in this video?

  Homozygous, heterozygous, genotype, phenotype
• Why is it important to learn definitions in this video?

  They are crucial for understanding genetics
• 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 genes?

  Sections of DNA on a chromosome
• What is a key fact about chromosomes?

  They come in pairs
• What are alleles?

  Versions of a gene
• What does the earwax gene control?

  The type of earwax produced
• How many alleles does the earwax gene have?

  Two alleles
• What does the capital letter 'E' represent?

  Wet earwax allele
• What does the lowercase letter 'e' represent?

  Dry earwax allele
• What is a person's genotype?

  The alleles present in an individual
• What is the genotype for a person with two copies of the dry earwax allele?

  Lowercase e lowercase e
• What does homozygous mean?

  Having two identical alleles
• What does phenotype refer to?

  The characteristics caused by alleles
• What is the phenotype for a person with two alleles for dry earwax?

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

  Capital E capital E
• What does it mean if a person is heterozygous?

  They have two different alleles
• What is the phenotype for a person with genotype capital E lowercase e?

  Wet earwax
• What is a dominant allele?

  Shows in phenotype with one copy
• What is a recessive allele?

  Shows in phenotype only with two copies
• How are most characteristics controlled?

  By many genes acting together
• What are the key definitions related to alleles and genotypes?

  • Dominant allele: Shows in phenotype with one copy
  • Recessive allele: Shows in phenotype with two copies
  • Homozygous: Two identical alleles
  • Heterozygous: Two different alleles
  • Genotype: The alleles present
  • Phenotype: The characteristics caused by alleles
• What is the relationship between genotype and phenotype in earwax production?

  • Genotype determines the alleles present
  • Phenotype is the observable characteristic
  • Dominant allele (E) leads to wet earwax
  • Recessive allele (e) leads to dry earwax
• How do dominant and recessive alleles interact in determining traits?

  • Dominant alleles mask the effect of recessive alleles
  • Recessive alleles only express when homozygous
  • Heterozygous individuals express the dominant trait
• What is the significance of alleles in genetics?

  • Alleles are variations of genes
  • They determine traits and characteristics
  • Understanding alleles is crucial for genetics