Genes are the means by which information is passed from parent
to offspring. Each adult human, for example, has 23 pairs of
chromosomes, each containing many genes that encode everything
from eye color to the way cells in our body use energy. During
reproduction, each parent contributes one chromosome from each
of the 23 pairs, so that the offspring is a unique recombination
of genes from the two parents.
Some diseases, like
Huntington’s disease, are genetically determined,
meaning that if one parent has the associated gene, and passes
it to an offspring, then the offspring will eventually develop
Huntington’s disease. Other diseases, like
Alzheimer’s disease and
Parkinson’s disease appear to depend partly on
several genes. An individual who inherits one or more of
these genes may be more likely to develop these diseases than
someone without the disease – but other factors like
environment and medical history appear to also play a role in
determining whether a particular individual will (or will not)
develop the diseases.
by Catherine E. Myers. Copyright © 2006 Memory Loss and the Brain |
