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?

  It tells us the alleles present
• What is a phenotype?

  It tells us the characteristics caused by alleles
• How many pairs of chromosomes do normal human cells contain?

  23 pairs
• From whom does one chromosome in a pair come?

  From the father
• What are alleles?

  Versions of a gene
• What is a dominant allele?

  An allele that shows in the phenotype with one copy
• What is a recessive allele?

  An allele that shows only with two copies
• 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: alleles present
  • Phenotype: characteristics caused by alleles