From Trait to Gene

1
From Trait to Gene

• Why does DNA contain so much information?!

2
Mendel found

• Different traits do not blend together to produce
  an in-between form.
• But..there are a few EXCEPTIONS!

3
Incomplete DominancePlace this Punnett Square on
the back of your notes!

• One trait is not completely dominate over another
• Each allele has its own degree of influence
• Ex Snap dragon flowers red, white, and pink
  petals
• Page 134

• One trait is not completely dominate over another
• Each allele has its own degree of influence
• Ex Snap dragon flowers red, white, and pink
  petals

R 1 R1


R2 R2
Genotype and Phenotypes?
4
Incomplete DominancePlace this Punnett Square on
the back of your notes!

• One trait is not completely dominate over another
• Each allele has its own degree of influence
• Ex Snap dragon flowers red, white, and pink
  petals
• Page 134

• One trait is not completely dominate over another
• Each allele has its own degree of influence
• Ex Snap dragon flowers red, white, and pink
  petals
• Page 134

R1 R1
R1R2 R1R2
R1R2 R1R2
R2 R2
Genotype and Phenotype R1R1 red R2R2
white R1R2 pink
5
Codominance Place this Punnett Square on the
back of your paper!

• When each trait is equally dominate
• Phenotype shows both parents alleles
• Ex Seed size big, little, and both

B B


L L
Genotype and Phenotypes?
6
Codominance Place this Punnett Square on the
back of your paper!

• When each trait is equally dominate
• Phenotype shows both parents alleles
• Ex Seed size big, little, and both

B B
BL BL
BL BL
L L
Genotype and Phenotypes BB Big seed LL Little
Seed BL Big and Little seeds
7
Web Genetic Lab Directory
http//www2.edc.org/weblabs/IncompleteDom/Incomple
teDominanceMenu.html
8
One Gene can Influence Many Traits

• Sometimes one gene can influence more than 1
  trait
• Example ? 1 gene

White Fur Blue Eyes
9
Many genes can influence a single trait

• When several genes act together on 1 trait
• What do you think some examples are?
• 1-
• 2
• 3
• Page 135

10
The Importance of Environment

• What could be some other factors influencing how
  we grow and develop?
• 1-
• 2-
• 3-
• 4-
• Page 135