Transcript 2 different alleles

What is DNA?
Variations in DNA can cause visible
changes in different individuals
Traits can be inherited!
Arlene Chambers
Traits are inherited through genes
Traits are inherited through genes
• Genes are on chromosomes
http://www.biotechnologyonline.gov.au
Traits are inherited through genes
• Genes are on chromosomes
• One chromosome inherited
from each parent
http://www.biotechnologyonline.gov.au
Traits are inherited through genes
• Genes are on chromosomes
• One chromosome inherited
from each parent
• We have two copies of each
chromosome, and thus, two
copies of each gene
http://www.biotechnologyonline.gov.au
Different versions of genes are alleles
Different versions of genes are alleles
For each gene, you might have…
2 different alleles
Different versions of genes are alleles
For each gene, you might have…
OR
2 different alleles
2 of the same allele
Different versions of genes are alleles
For each gene, you might have…
OR
2 different alleles
2 of the same allele
Combinations of alleles determine what traits you have
Can you roll your tongue?
Can you roll your tongue?
Yes! You carry a copy of
the dominant allele.
OR
Can you roll your tongue?
Yes! You carry a copy of
the dominant allele.
OR
No! You have two copies of
the recessive allele.
Can you roll your tongue?
Yes! You carry a copy of
the dominant allele.
No! You have two copies of
the recessive allele.
OR
If you inherit both alleles, the dominant one is expressed.
Can you roll your tongue?
Yes! You carry a copy of
the dominant allele.
No! You have two copies of
the recessive allele.
OR
If you inherit both alleles, the dominant one is expressed.
Dominant does NOT mean more common!
The Genetic Wheel
Single-gene Traits
L – dimples
(dominant)
ll – no dimples
(recessive)
If you have laugh dimples, your genetic
wheel will look like this…
L
ll
Single-gene Traits
T – can roll tongue
(dominant)
tt – cannot roll tongue
(recessive)
Single-gene Traits
C – left thumb on top
(dominant)
cc – right thumb on top
(recessive)
Single-gene Traits
P – pinkies bend away
(dominant)
pp – pinkies are straight
(recessive)
Single-gene Traits
E – ear lobe is free
(dominant)
ee – ear lobe is attached
(recessive)
Single-gene Traits
W – has widow’s peak
(dominant)
ww – no widow’s peak
(recessive)
Single-gene Traits
B – thumb is straight
(dominant)
bb – thumb bends back
(recessive)
ww
bb
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Genetic Wheel Results
There are 128 possible
combinations from the
7 traits illustrated on the
genetic wheel.
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Are you the same as
anyone else?
71
Genetic Wheel Results
There are 128 possible
combinations from the
7 traits illustrated on the
genetic wheel.
32
Are you the same as
anyone else?
71
If this much genetic variation exists in traits that are visible,
imagine how different we all are in ways that we can’t see!