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.
Our bodies are made up of millions of cells (100,000,000,000,000), each with their own complete set of instructions for making us, like a recipe book for the body. This set of instructions is known as our genome and is made up of DNA. Each cell in the body, for example, a skin cell or a liver cell, contains this same set of instructions: The instructions in our genome are made up of DNA. Within DNA is a unique chemical code that guides our growth, development and health. This code is determined by the order of the four nucleotide bases that make up DNA, adenine, cytosine, guanine and thymine, A, C, G and T for short. DNA has a twisted structure in the shape of a double helix. Single strands of DNA are coiled up into structures called chromosomes. Your chromosomes are located in the nucleus within each cell.