23 Summary • What is the hereditary material? The molecule DNA. • What is the chemical and physical structure of DNA? It is a double helix of two chains of nucleotides, inter-twined in opposite orientation. At the center of the helix, nucleotides with G pair with C, and those with A pair with T. • How is DNA copied in the formation of new cells and in the gametes that will give rise to the offspring of an individual? The strands separate, and each is used as a template for building a new strand. • What are the functional units of DNA that carry information about development and physiology? The functional units are genes, regional units bearing the appropriate signal sequences for being transcribed into RNA. • What molecules are the main determinants of the basic structural and physiological properties of an organism? Many thousands of different types of proteins. KEY QUESTIONS REVISITED • What are the steps in translating the information in DNA into protein? For most genes, ±rst, transcription of the DNA sequence into mRNA, then translation of the RNA sequence into the amino acid sequence of protein. • What determines the differences between species in
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.