Transcript Chapter 5 Heredity & Genetics

IV. Source of Gene Variations: When cells divide each
DNA molecule in the cell makes exact copies of
itself. But sometimes the cell makes a mistake;
bases may pair up incorrectly. The codon are
changed the altered gene is passed on to the new
cell.
A- Mutation is any permanent change in the
DNA of a cell.
1. Mutation increases with the exposure of DNA
to some chemicals ands radiation that damage
the DNA molecule.
B. Chromosome Mutation: When a piece of
chromosome breaks and are rearranged or lost.
During meiosis chromosomes mutation may occur
when chromosomes do not separate evenly.
1. Muscular Dystrophy= Weak muscles.
2. Down Syndrome or Trisomy 21= is caused as a result
of a sex cell having too many 21st chromosomes. The
fertilized egg, contains three 21st chromosomes instead
of two.
3. Importance of Mutations= are a source of new traits
or new forms of traits.