Complete Dominance Complete dominance: the allele that is regarded as dominant completely masks the effect of the allele that is recessive. Dominant alleles are written with capital letters and recessive alleles are written with lower case letters. For example, purple flowers are dominant to white flowers. A homozygous white flower is crossbred with a homozygous purple flower. What are the phenotypes of the offspring?

Here’s one where red and white make pink Incomplete Dominance Incomplete Dominance: Both alleles are capitals because the alleles are not dominant or recessive **neither one takes over or hides ….not dominant or recessive…they MIX TOGETHER! Like mixing paint! The outcome is in-between!! R=Red Flowers B=Blue Flowers RR=Red Flowers BB=Blue Flowers RB=Purple Flowers Here’s one where red and white make pink

Try These Punnett Squares…please Cross a Blue flower with a red flower. Cross a red flower with a purple flower. Cross two purple flowers.

Codominance Same deal with the alleles…all letters will be capital. This time they are both being dominant. It’s like splattering one color on another-they both show up equally dominant. For example, you have a homozygous black feathered chicken who mates with a homozygous white feathered chicken. Their offspring will have BOTH white and black feathers. Results in a third phenotype: speckled.

So…Codominant Alleles R=Red Fish B= Blue Fish RR=Red Fish BB=Blue Fish RB=Red and Blue Fish (like spots or stripes)

Now Try These Punnett Squares…please Cross a Blue fish with a red fish. Cross a red fish with a red and blue fish. Cross two red and blue fish.

Blood Type is also Codominant Blood types A and B are codominant. When present, they are both expressed. However, Blood type O is recessive. When present with dominant alleles, it is masked.

Blood Type Examples A man with AB blood is married to a woman with AB blood. What blood types will their children be and in what proportion? A woman with type A blood (genotype: AO) is married to a type B person (genotype: BO). What blood types will their children have?

Can You Pick Out the Co-dominant and Incompletely dominant Example Can You Pick Out the Co-dominant and Incompletely dominant Example? Silly Question…of course you can

See…You Did it

Sex-linked Sex-linked traits are carried on the sex chromosomes. The sex chromosomes are 23 pair. XX = female XY = male Because, males only have one X chromosome, they have a much greater chance of having sex-linked traits.

Examples of Sex-Linked Traits Hemophilia Blood lacks clotting factor, most of which are produced in the liver. Colorblindness a problem with the color-sensing cones in the retina of the eye. You can’t see certain colors Red/Green-most common Blue Yellow Achromatopsia-see greys only

Colorblindness Example Colorblindness is a recessive disorder carried on the X-chromosome. A female carrier of colorblindness and a normal male want to have children. What is the probability they will have a child who is colorblind?