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Heredity and Genetics
Mrs. Bailey
Bellringer
• If a tall pea plant with alleles (TT) was
crossed with a short pea plant with alleles
(tt) and all of the offspring were tall (Tt),
what is the dominant allele? What is the
recessive allele?
• a. T
b. t
Heredity/Genetics
• Who do you look like? You may have the
same eye color, nose shape, and many
other physical features known as_______.
• Traits can also include unseen
characteristics such as blood type.
• When traits are passed from parents to
offspring we call it ____________.
Heredity/Genetics
• How are these traits
passed to the offspring?
• Traits are passed through
genes ( a section of DNA
) found on ___________.
• There are different forms
of a trait. We call them
_______. If they are the
same allele they are
called ________. If they
are different alleles they
are ___________
Heredity
• Chromosomes that
contain alleles for eye
color. One allele
codes for brown (B),
the other blue (b).
• What color eyes will
the offspring have?
That depends on
which allele is ____
• ________________
Heredity/Genetics
__________ alleles always cover up the
expression of the traits of recessive alleles.
– Represented by a capital letter.
• __________ alleles are always covered up
unless there are two recessive alleles present.
– Represented by a lower case letter.
• The way an organism physically appears is
called its phenotype.
• The combination of an organism’s genes/alleles
is called its genotype
Example
• T=tall; t=short
• 1. An organism has the genotype (TT).
– What is the dominant allele? Recessive?
– What is phenotype?
– Is the organism heterozygous or
homozygous?
Answers
• The dominant allele is _________). The
recessive allele is _________.
• The organism’s phenotype (physical
appearance) is _________.
• _____________ because ______ alleles
are __________.
Group example
• If T=tall; t=short
• 1. An organism has the genotype (Tt).
– What is the dominant allele? What is the recessive
allele?
– What is phenotype?
– Is the organism heterozygous or homozygous?
2. If an organism is short what is its genotype?
Are the alleles homozygous or heterozygous?