Alleles, phenotypes and genotypes, dominant

• What is an allele?

  A different version of the same gene
• What is the difference between dominant and recessive alleles?

  Dominant alleles are expressed over recessive ones
• What does homozygous mean?

  Having two identical alleles for a gene
• What does heterozygous mean?

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

  The entire collection of alleles an organism has
• What is a phenotype?

  The characteristics derived from an organism's genotype
• If a mouse is heterozygous for fur color with one allele for purple and one for green, what color will it be if purple is dominant?

  It will be purple
• What must be true for a mouse to be green?

  It must be homozygous recessive for green fur
• How does the expression of the purple allele differ from the green allele?

  The purple allele is always expressed when present
• How do the genotypes of the three mice differ?

  They have different alleles and genetic codes
• Why do the heterozygous and homozygous dominant mice have the same phenotype?

  Both express the dominant purple color
• What is the phenotype of the homozygous recessive mouse?

  It is green
• What are the key terms related to genes discussed in the video?

  • Allele
  • Dominant
  • Recessive
  • Homozygous
  • Heterozygous
  • Genotype
  • Phenotype
• How do genes influence characteristics in organisms?

  • Genes are segments of DNA coding for proteins
  • Traits can be determined by single or multiple genes
  • Interaction of genes leads to diverse characteristics
• What is the relationship between alleles and genes?

  • Alleles are different versions of a gene
  • Each gene has two alleles from parents
  • Alleles can be homozygous or heterozygous
• What is the significance of dominant and recessive alleles in phenotype expression?

  • Dominant alleles are expressed in phenotype
  • Recessive alleles are only expressed when homozygous
  • Phenotype can be the same for different genotypes