Have you ever heard a news reporter
talk about DNA? Reporters talk about DNA found at the scene of a crime. They
talk about police finding DNA “fingerprints.” Police sometimes use DNA as a clue
to find out who committed the crime.
WHAT IS DNA?
DNA is a substance that makes up
genes. Everything alive has genes. Plants have genes. Animals have genes. You
have genes.
Genes are the basic units of
heredity. Heredity means all the characteristics you inherit from your parents.
You get your genes from your parents. You inherit half of your genes from your
mother. You inherit half of your genes from your father.
Genes are a kind of code. A tree’s
genes tell what shape its leaves will be. A cat’s genes tell what color its fur
will be. Your genes tell what color your eyes will be. Your genes tell what
color your hair will be. Everything about you comes from the code in your
genes.
WHERE ARE GENES?
Genes line up on strands called
chromosomes in cells. Everything alive is made up of cells. Chromosomes are in
the center, or nucleus, of cells.
Different parts of you are made of
different kinds of cells. Your muscles are made of muscle cells. Your skin is
made of skin cells. The code in your genes tells your body to make different
kinds of cells. The genes in each cell tell the cell how to work. They tell the
cell when to make new copies of itself.
WHO DISCOVERED GENES?
An Austrian monk named Gregor
Mendel first saw inherited patterns in pea plants. He experimented with pea
plants in the 1860s. One of the things, or traits, Mendel studied was what makes
some pea plants tall and some short. He said that the traits must come from
units of heredity passed from the parent plants. These units were later called
genes.
In the mid-1900s, scientists
discovered that genes are made of DNA. In the 1970s, scientists learned how to
change DNA with genetic engineering. Scientists also learned that problems with
certain genes cause diseases. Muscular dystrophy, cystic fibrosis, and
hemophilia are some genetic diseases—diseases caused by problems in genes.
Today, scientists are looking for ways to cure genetic diseases by altering
genes through a process called gene therapy.Microsoft ® Encarta ® 2006.