Genes play a complex and not yet fully understood role in human life. Their part in Alzheimer’s disease (AD) is no exception. The more researchers learn about AD, the more they become aware of multiple factors, including genetics and certain biological processes, that work together in the development of AD. Recent excitement has centered around the discovery of the relationship between apolipoprotein E (apoE) and AD.
Like recipes, genes provide instructions about how to make something: what ingredients go in and in what order. But, the environment (things outside the body like food, the air we breathe, or chemicals we are exposed to) and biological processes (inside the body) determine which ingredients are available and in what quantities and forms.
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Along with environmental influences, genes and other processes inside the body combine to do more than just determine eye and hair color and other traits inherited from parents. Genes also see to it that people have two arms and two legs and can walk. In almost every case, nature (genes) and nurture (including the physical and chemical environment) work together to shape all living things.
Genes are not all-powerful. Most genes can do little unless spurred on by other substances. Although they are necessary in their own right, genes basically wait inside the cell’s nucleus (or control center) for other molecules to come along and read their messages. Within the nucleus of every human cell, two long, thread-like DNA strands encode the instructions for making all proteins needed for life. Each cell holds more than 50,000 different genes found on 46 chromosomes of tightly coiled DNA. Each DNA strand bears four types of coding molecules or bases. The sequence of bases in a gene is the code for protein manufacture.
Sometimes genes are triggered to build a certain protein. They may build a protein correctly or, in some cases, incorrectly, depending on the substances that interact with them. A gene also can produce a faulty protein if it has one or more mutations (defects) in its DNA (deoxyribonucleic acid). Faulty proteins can lead to cell malfunction, disease, and death.
Source: Connection Magazine [Volume 5(1), Winter/Spring 1996]