Non-Mendelian Genetics

Non-Mendelian Genetics

• Some dominant alleles are NOT stronger than recessive alleles...they coexist

• Dominance ranges from:

complete dominance🡪 incomplete dominance 🡪
codominance

INCOMPLETE DOMINANCE

•Offspring appearance is

somewhere in between the
phenotypes of the parents

•Examples Snapdragons Flower

Color:

•Parents Phenotypes:

Red CRCR x

white CWCW

•Offspring: 100% pink CWCR

CODOMINANCE

•Traits have two dominant
alleles

•Each one is expressed

individually in the offspring
•Example 1: Chicken Feather

• Black Feathers: BB
• White Feathers: WW
• Speckled Black and White: BW

•Example 2: Roan Cows (red and white hairs)

• Red Cow: RR
• White Cow: WW
• Roan Cow: RW

CHICKEN FEATHERS: CODOMINANCE

Multiple Choice

this image is an example of

• codominance
• dominance
• incomplete dominance

Multiple Choice

A breed of chicken shows codominance for feather color. One allele codes for black feathers, another codes for white feathers. The feathers of heterozygous chickens of this breed will be:

• all black
• all white
• all gray
• speckled black and white

Multiple Choice

In some carnations, flower color exhibits codominance. Identify the correct genotypes for red, white, and speckled carnations.

• Red = RR, white = rr, speckled = SS

• Red = RR, white = WW, speckled = SS

• Red = RR, white = RW, Speckled = WW

• Red = RR, white = WW, speckled = RW

Multiple Choice

If this image were real, it would represent what type of inheritance?

• incomplete dominance
• codominance
• polygenic inheritance
• compete dominance

Multiple Choice

A red flowered plant (RR) breeds with a White flowered plant (WW). The gene for petal color in these plants expresses incomplete dominance.  What percentage of the offspring will have pink (RW) flowers?

• 0%
• 25%
• 50%
• 100%

Multiple Choice

A roan cow shows codominance in fur color (brown and white). What is the phenotype ratio expected in offspring a female roan and a male roan mate together?

• All four would be brown and White

• Half would be orange, half would be white

• 2 Brown: 2 Brown and White: 0 White

• 1 Brown: 2 Brown and White: 1 White

Multiple Choice

Some flowers are controlled by codominance. Red flowers (RR), blue flowers (BB) and Speckled flowers (RB).

Cross a red flower with a speckled flower. What is the phenotypic ratio?

• 2 red, 2 speckled

• 2 red, 2 blue

• 2 blue, 2 speckled

Multiple Choice

In mice coat color is incompletely dominant. Black and white are homozygous. Brown mice are heterozygous.

What is the genotype for a brown mouse?

• BB

• Bb

• bb

Multiple Select

Based on the Punnett Square shown above, what is the percentage of getting a RW offspring?

• 50%

• 75%

• 25%

• 100%

Multiple Choice

What will these offspring look like?

• pure red

• pure white

• red and white spots

• pink