Non- Mendelian Inheritance When Mendel studied pea plants, he happened to select traits that were
A general term that refers to any pattern of inheritance in which traits do not determined by two alleles where one allele was completely dominant over the other
segregate in accordance with Mendel's laws. allele. For instance, for flower color in peas, purple flowers are dominant and white
The trait is determined by more than one gene (polygenic inheritance) or flowers are recessive. But some patterns of inheritance are different than the ones
environment affects the trait. Mendel discovered.
When a red snapdragon is crossed with a white snapdragon, the next
Punnett Square
generation will have all pink flowers! Because red and white blend, this is an
A chart that helps us predict the probable genotype of offspring.
example of a pattern of inheritance called incomplete dominance. In incomplete
dominance, the phenotypes of the two alleles blend.
Cross between red and white snapdragon
100% -pink (phenotype)
100% - RW (genotype)
In incomplete dominance, two capital letters are mostly used to represent two
different alleles. R for red color and W for white color
The genotype for red colored snapdragon is RR while for white colored
snapdragon is WW. The resulting genotype which is pink is RW.
Genotype – are gene combinations for a trait
- genetic constitution of an individual (RR,rr,Rr)
R R
Phenotype – are the physical traits or characteristics resulting
from a genotype (white, pink, checkered, round, W RW RW
etc.)
W RW RW
The table below summarizes the genotypes and phenotypes of snapdragons under
incomplete dominance.
Genotype Phenotype
Red RR Red
White WW White
Pink RW Pink
Incomplete Dominance
Phenotype and Genotype Non – Mendelian Inheritance
ACTIVITY:
1. Refer to the table below.
PHENOTYPE GENOTYPE
RED RR
WHITE WW
PINK RW
2. Write the genotype and phenotype of the offspring when pink flower is
crossed to a
white flower.
3. Write the genotypic and the phenotypic ratio of the offspring.
Genotypic Ratio __________________________
Phenotypic Ratio __________________________
1.Read the given problem. 2. Which of the following refers to the physical characteristics of an individual?
MangMarcelino owns purebred red cows. In his farm he noticed that after a A. Genotypes B. phenotypes C. nitrogenous base D. alleles
typhoon several months ago, all of the fences that separate his cattle from his
neighbor’s cattle were destroyed. During the time that the fences were down, 3. Which of the following refers to gene combinations for a trait?
three bulls, one from each neighbor, mingled with his cows. For a while, he A. Phenotype B. genotype C. Prototype D. hepnotype
thought that none of the bulls found his cows, but over the months, he noticed
that all of his cows are pregnant. He suspected that one of the bulls is the 4. The red cows crossed with white cows will have an offspring that are Roan cows.
father. Which bull is it? Help MangMarcelino look for the father by solving the Roanrefers to a cow with red hair and white blotches. What is the genotype of a
given problem. Roan?
A. WW B. . RW C. Wr D. RR
5. Which of the following should be the genotypes and the phenotypes of the parent
2. Determine the possible traits of the calves if: cattle if you want Roan fur cattle?
a red (RR) bull is mated with a red (RR) cow 1
a red (RR) bull is mated with a white (WW) cow 2 A. White (WW) X White (WW) Cattle C. Red (RR) X Red (RR) Cattle
a roan (RW) is mated with a red (RR) cow 3 B. Red (RR) X White (WW) Cattle D. Roan (RW) X Roan (RW) Cattle
3. Illustrate your answers using a Punnett square. 6. The following are examples of codominance EXCEPT?
A. Birds can be blue, white, or white with blue-tipped feather.
B. Flowers can be white, pink, or red.
GUIDE QUESTIONS: C. A bleexo can be spotted, black or white.
D. Appaloosa is white horse with gray spots.
Q1. Will you be able to trace the father of the calves? What are the possible 7. Which of the following is an example of phenotype?
phenotypes of the calves for each cow? A. An allele for brown eye C. Anemia due to lack of iron
B. An egg cell with an allele for blue eyes D. Curly hair
8. Which of the following BEST explains a Non-Mendelian Law of Inheritance?
Q2. Do you think you will make Mang Marcelino happy about the result of your
A. Shows both recessive traits of the parents.
investigation?
B. Shows both dominant traits of the parents.
C. Shows recessive traits and hides dominant traits.
D. Shows dominant traits and hides recessive traits.
Q3. How will you explain it to him?
9. Which of these represents a homozygous dominant genotype?
SUMMATIVE TEST: A. MM B. Mm C. mm D. M
10. Which of the following is a type of inheritance in which two dominant alleles are
Multiple Choice: Directions: Read each item carefully and write your answers in ½ expressed at the same time without blending of traits?
crosswise.
1. Which of the following will be the phenotypic ratio of a cross between a A. Incomplete Dominance
homozygous red-flowered snapdragon (RR) and a homozygous white flowered B. Multiple Alleles
snapdragon (WW)? C. Codominance
A. 100 % pink C. 75 %pink; 25 % red D. Heterozygous
B. 50% red; 50% white D. 50% pink; 25%red;25%white
