Dihybrid crosses

1
Dihybrid crosses

• Crossing 2 different traits at the same time
  (like pea color and plant height)
• Example problem
• Cross a heterozygous yellow, short pea plant with
  a homozygous dominant yellow, homozygous dominant
  tall plant.

Yellow,tall Yellow,short Green,tall
Green,short
Phenotypic ratio ____________________
2
Figure 14.2 Mendel tracked heritable characters
for three generations
3
Figure 14.9x Incomplete dominance in carnations
4
Figure 14.9 Incomplete dominance in snapdragon
color
5
Codominance

• Both alleles are dominant causing the physical
  appearance to show both characteristics.

When crossing codominant traits, use different
capital letters.
RR red phenotype RW roan phenotype
WW white phenotype
Some people, like incomplete dominance, use
superscripts or subscripts w/ diff letters CRCR
red or CRCR red CRCW roan..etc.