alleles

• What do homozygous and heterozygous refer to?

  Types of genotypes based on allele pairs
• What are genes?

  Sections of DNA on a chromosome
• How many copies of every gene do humans have?

  Two copies of every gene
• What is the gene that controls earwax?

  The earwax gene
• What are alleles?

  Versions of a gene
• What does homozygous mean?

  Having two identical alleles
• What does phenotype refer to?

  Characteristics caused by alleles
• What does heterozygous mean?

  Having two different alleles
• What is a dominant allele?

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

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

  • Most characteristics result from many genes acting together
  • Example: Height is influenced by multiple genes