Genotypes & Phenotypes

• What does a genotype represent?

  A genotype represents the allele combinations at a specific gene locus.
• How are dominant alleles represented in genotypes?

  Dominant alleles are represented with a capital letter.
• How are recessive alleles represented in genotypes?

  Recessive alleles are represented with a lowercase letter.
• What is a phenotype?


  A phenotype refers to the physical or biochemical characteristics of an organism that arise from gene expression and the environment.
• What are the different types of dominance patterns in phenotypes?

  • Complete dominance: dominant alleles completely mask recessive alleles.
  • Codominance: both alleles are expressed.
  • Incomplete dominance: neither allele is wholly expressed, resulting in an intermediate phenotype.
• What occurs in complete dominance?

  In complete dominance, dominant alleles completely mask the expression of recessive alleles.
• What is codominance?


  Codominance occurs when both alleles from the genotype are fully expressed in the phenotype of a heterozygote.
• What is incomplete dominance?


  Incomplete dominance occurs when neither allele from the genotype is fully expressed, resulting in a blending of both alleles.
• What does it mean to be homozygous for a gene?

  An individual is homozygous for a gene if they inherit two identical alleles from both parents.
• What does it mean to be heterozygous for a gene?

  An individual is heterozygous for a gene if they have two different alleles for the same gene.
• How is a dominant allele characterized?

  A dominant allele is the stronger form of a pair of alleles and is expressed even if only one copy is present.
• How is a recessive allele characterized?

  A recessive allele is the weaker form of a pair of alleles and is only expressed if two copies are present.
• What does it mean for a person to be a carrier of a recessive allele?

  A person who is heterozygous at a specific gene locus is a carrier and can pass on the recessive allele to their offspring.
• What is the significance of sex-linked genes?


  Sex-linked genes are present on the X or Y chromosomes and can affect the expression of traits differently in males and females.
• Why are X-linked traits more likely to be expressed in males?

  1. linked traits are more likely to be expressed in males because they receive only one copy of the X chromosome from their mother.
• Can males with X-linked traits pass the trait on to their sons?

  No, males with X-linked traits cannot pass the trait on to their sons because sons inherit the Y chromosome from their father.
• How can affected males pass on X-linked traits?

  Affected males can only pass on the abnormal X-linked gene to their daughters.