Transcript Introduction to Genetics

Introduction to
Genetics
 Heredity
is the passing of traits
from parents to offspring.
 Genetics is the study of heredity.
 Gregor Mendel is known as the
father of genetics.
Who was Mendel?
 Mendel
was a monk who lived in a
monastery in Austria
 He spent a lot of time gardening and
became interested in why plants
looked the way that they did.
 Mendel studied the characteristics of
pea plants to see how traits were
passed from parents to offspring.
Mendel’s Discovery
 Mendel
noticed that some traits
showed up more often than
others. He called these traits
dominant – they will cover up
another trait that is present.
 Recessive traits are the traits that
get covered up. You only see
recessive traits if you get one
from each of your parents.
 Genes
are the sections of DNA
that carry information about a
certain trait.
 The different forms of a trait
(whether it is dominant or
recessive) are called alleles.
 Dominant
alleles are always shown
with a capital letter.
 Recessive alleles are always shown
with a lower case letter.
 Alleles
are represented with a
genotype – a letter combination.
 If
the two letters in a genotype are
the same, it is said to be
homozygous
 If the two letters are different (one
capital, one lower case), it is said to
be heterozygous.
 The
phenotype is the physical
appearance of a trait.
Mendel’s Laws of Genetics
Mendel’s Law of Segregation states that
because of meiosis, each gamete that is
made only only receives 1 copy of each
gene.
 Mendel’s Law of Independent Assortment
states that the alleles of different genes
sort independently of each other during
meiosis. In other words, inheriting one
trait cannot influence another trait.
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Mendel’s Law of Dominance states that if
you have a heterozygous organism, you
will only see the dominant trait and the
recessive will be hidden.