Suggested problems: Chapter 3: 1, 2, 6, 7, 8, 12, 18, 20, 22, 26, 28, 30, 34
Chapter 4: 1, 2, 4, 6, 10, 12, 16, 20, 24, 30, 32, 34
The beginning of modern genetics and the basis for our
understanding of genetics starts with Mendel’s discoveries of the
Mendel established the inheritance of traits via physical units
(which we now call “genes
”), although the physical/chemical basis
for these traits was unknown.
In a way this is analogous to seeing an animal track in the snow
and knowing that a physical entity (ie, an animal) must have
made the track, even though you don’t know what the animal
He worked with single inherited traits in garden peas (
), and worked on (or reported) only the simplest cases:
traits determined by only one gene
What Mendel figured out was essentially as follows; for cells of
” life forms (everything above bacteria):
Genes come in pairs (with some exceptions).
There are two copies of each
of 1000’s of genes.
The copies can be identical.
The two copies may be slightly different forms of each
”); one gene may have many
alleles if the entire population is considered. (
For example, for gene x, one individual may be
, a second may be x
, a third may be x
While not exactly
the same, gene and allele are often