Post on 14-Dec-2015
What is DNA?
Variations in DNA can cause visible changes in different individuals
Traits can be inherited!
Arlene Chambers
Traits are inherited through genes
http://www.biotechnologyonline.gov.au
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
Different versions of genes are alleles
2 different alleles
Different versions of genes are alleles
For each gene, you might have…
2 different alleles 2 of the same allele
OR
Different versions of genes are alleles
For each gene, you might have…
2 different alleles 2 of the same allele
OR
Different versions of genes are alleles
For each gene, you might have…
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.
OR
No! You have two copies of the recessive allele.
If you inherit both alleles, the dominant one is expressed.
Can you roll your tongue?
Yes! You carry a copy of the dominant allele.
OR
No! You have two copies of the recessive allele.
Dominant does NOT mean more common!
If you inherit both alleles, the dominant one is expressed.
The Genetic Wheel
Single-gene Traits
L – dimples (dominant)
ll – no dimples (recessive)
Laugh DimplesLaugh Dimples
L
l l
If you have laugh dimples, your genetic wheel will look like this…
Single-gene Traits
Tongue Rolling
Tongue Rolling
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)
Hand ClaspingHand Clasping
Single-gene Traits
P – pinkies bend away (dominant)
pp – pinkies are straight (recessive)
PinkiesPinkies
Single-gene Traits
E – ear lobe is free (dominant)
ee – ear lobe is attached (recessive)
Ear LobesEar Lobes
Single-gene Traits
W – has widow’s peak (dominant)
ww – no widow’s peak (recessive)
Widow’s PeakWidow’s Peak
Single-gene Traits
B – thumb is straight (dominant)
bb – thumb bends back (recessive)
Thumb BendThumb Bend
3232ww bb 32
32
There are 128 possible combinations from the
7 traits illustrated on the genetic wheel.
Are you the same as anyone else?
Genetic Wheel Results
71
32
There are 128 possible combinations from the
7 traits illustrated on the genetic wheel.
Are you the same as anyone else?
Genetic Wheel Results
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!