alleles

• what is the difference between a gene and an allele?

  Gene: unit of heredity that is passed from parent to offspring. Allele: different forms of a gene that can occupy the same locus on a chromosome.
• why will a recessive allele not effect the phenotype of an organism that is heterozygous for that gene?

  Recessive alleles only express their phenotype if an organism carries two identical copies of the recessive allele
• why are genetic diagrams useful?

  they show the inheritance of traits, can predict the ratios of the phenotypes.
• list these terms in order of size, largest first: base, chromosome, gene, genome

  genome, chromosome, gene, base
• define the term allele. A version of a gene.
• how does the idea of alleles help to explain why we all look different
• when will a recessive allele effect the phenotype?

  if an organism carries two identical copies of the recessive allele