12c. Explain why the sister chromatids in each chromosome always have the same alleles for each gene. All of a person’s body cells have the same combination of alleles; this combination of alleles is the person’s genotype. The person’s observable characteristics are called the phenotype. This table shows how different genotypes provide the instructions to make different versions of a protein, and these different versions of the protein result in different phenotypes. (characteristics) Protein Phenotype Genotype Enough normal enzyme to AA or Aa Normal skin and hair color make melanin in skin and hair Defective enzyme that cannot aa Very pale skin and hair color; albino make melanin Enough normal hemoglobin to SS or Ss Normal blood; no sickle cell anemia prevent sickle cell anemia Sickle cell hemoglobin, which Sickle shaped red blood cells can block blood ss can cause red blood cells to flow in small blood vessels, causing pain, become sickle shaped organ damage, anemia; sickle cell anemia 13. Explain why a person with the aa genotype has very pale skin and hair color. Include the words enzyme and melanin in your explanation. 14. Suppose that Amanda’s cells have the pair of homologous chromosomes shown in the drawing at the top of the page. What is Amanda’s genotype? aass ___ AaSS ___ AASS ___ Is Amanda an albino? yes ___ no ___ Which does Amanda have? sickle cell anemia ___ normal blood ___ Modeling Mitosis with One Pair of Homologous Chromosomes Complete each step in this modeling procedure and check the box. Get a pair of model homologous chromosomes, one with the a and s alleles and the other with the A
12c. Explain why the sister chromatids in each chromosome always have the same alleles for each gene. All of a person’s body cells have the same combination of alleles; this combination of alleles is the person’s genotype. The person’s observable characteristics are called the phenotype. This table shows how different genotypes provide the instructions to make different versions of a protein, and these different versions of the protein result in different phenotypes. Genotype Protein Phenotype (characteristics) AA or Aa Enough normal enzyme to make melanin in skin and hair Normal skin and hair color aa Defective enzyme that cannot make melanin Very pale skin and hair color; albino SS or Ss Enough normal hemoglobin to prevent sickle cell anemia Normal blood; no sickle cell anemia ss Sickle cell hemoglobin, which can cause red blood cells to become sickle shaped Sickle shaped red blood cells can block blood flow in small blood vessels, causing pain, organ damage, anemia; sickle cell anemia 13. Explain why a person with the aa genotype has very pale skin and hair color. Include the words enzyme and melanin in your explanation. 14. Suppose that Amanda’s cells have the pair of homologous chromosomes shown in the drawing at the top of the page. What is Amanda’s genotype? aass ___ AaSS ___ AASS ___ Is Amanda an albino? yes ___ no ___ Which does Amanda have? sickle cell anemia ___ normal blood ___ Modeling Mitosis with One Pair of Homologous Chromosomes Complete each step in this modeling procedure and check the box. Get a pair of model homologous chromosomes, one with the a and s alleles and the other with the A