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!