Once you are done with this lesson you should be able to: 1  Identify the Abbasids. 2  Describe the roles of the caliphs and the viziers. 3  Explain how the caliphs' focus on trade led to the Golden Age of Islam. 4  Summarize the fall of the Abbasids.
Alleles are forms of the same gene with small differences in their sequence of DNA bases. These small differences contribute to each personâs unique physical features. Genes are made up of DNA.Each chromosome contains many genes. A gene is the basic physical and functional unit of heredity. Genes, which are made up of DNA, act as instructions to make molecules called proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases.lleles are forms of the same gene with small differences in their sequence of DNA bases. These small differences contribute to each personâs unique physical features. Genes are made up of DNA.
Genes are sections of the DNA. Each gene has the code for creating a specific protein. The sequence of bases in the gene controls which amino acids are created and joined to make a specific new protein (or enzyme) molecule. Amino acids are made in the number and order dictated by the number and order of base triplets. 2  Finally, the amino acid molecules join together in a long chain to make a protein molecule. 3  The number and sequence of amino acids determines which protein results.