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1.3 process information from secondary data to outline the current understanding of gene expression

process information from secondary data to outline the current understanding of gene expression

Some useful information

A gene is a piece of a DNA molecule that codes for a specific polypeptide. (One gene-one polypeptide theory.) The sequence of bases on the portion of the DNA molecule (gene) ultimately determines the sequence of amino acids in the polypeptide produced. Polypeptides join to become proteins. Examples of proteins include enzymes, hormones and structural proteins in cell membranes. Proteins control all chemical reactions and hence all cell activities. In this way, genes determine the characteristics of an organism. Gene expression occurs through polypeptide synthesis, protein synthesis and the functioning of that protein.

Genes are regulated and controlled by various short DNA sequences. Protein products from these genes either activate (“turn on”) or inactivate (“turn off”) the expression of these genes. In multicellular organisms, differentiated cells only have a small number of their genes activated eg. muscle cells only have those genes turned on that control muscle factors.