Download Introduction to Genetics

Important words to know

Study of heredity

Studies the way in which genetic/hereditary
information is passed on from parents to
offspring
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
During sexual reproduction, when a sperm
and egg meet
Produces a new cell, with some DNA from
the mom and some from the dad

Sex cells


Sperm
Egg

Means self-pollinate

Ex: some plants have “male” and “female” sex
organs, so can produce offspring identical to
themselves

Ex: pea plant, apricot, avocado, grapes

A specific characteristic


Varies from one individual to another
Ex: eye color, human height, seed color, plant
height

Contain hereditary information (DNA)

Specific unit of hereditary
material located on a
chromosomes

Genes code for specific traits

Different forms of a gene

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Ex: The gene controlling hair color exists as an
allele for blond hair or an allele for brown hair.
Ex: in plants, the gene controlling height either
exists as an allele for tallness or an allele for
shortness.

Some alleles are dominant and some alleles
are recessive.
Dominant Alleles
An organism with a
dominant allele for trait
will always exhibit that
trait.
Dominant expressed by
capital letter
Recessive Alleles

 An organism with a
recessive allele for a trait
will show that trait if the
dominant allele is not
present.

 Recessive expressed by
lower case letter
•In pea plants, the alleles for height is either T or t. Which is
the recessive allele?
•If we were looking at human eye color, pick a letter to
represent eye color. Now show the difference between brown
(dominant) and blue (recessive) alleles?

Offspring from parents with different traits

Ex: yellow corn and white corn offspring with
both colors

Offspring has the DNA from both parents