Codominance

Examples of Codominance. The best example, in this case, is the codominance blood type. ABO group is considered to be a codominant blood group where both father’s and mother’s blood group is expressed. It means that the properties of the blood groups exist in the ABO type.
Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked.

1. Rajendra Chavhan NON-MENDELIAN INHERITANCE PRESENTED BY Dr. RAJENDRA CHAVHAN Assistant Professor in Zoology, Mahatma Gandhi Arts, Science and Late N. P. Commerce College Armori , District Gadchiroli CODOMINANCE

2. CODOMINANCE =No blending CODOMINANCE: - “Co” means together. Co-dominance: It is a subtypes of Non- Mendelian heritance. Co-dominance is believed to be a violation of the Law of Dominance . In Heterozygous both alleles show their effects equally. Alleles do not show blended Phenotype . In CODOMINANCE, the “recessive” & “dominant” traits appear together in phenotype of hybrid organisms. When both allele of pair are fully expressed in a heterozygote, called co-dominant alleles. Such alleles exhibit a unique pattern of expression with heterozygous being phenotypically distinguishable from both of the homozygous and expressing both alleles equally.

3. CODOMINANCE (Popular Examples) CODOMINANCE:- The condition in which both alleles in a heterozygous organism are expressed. BOTH alleles contribute to the phenotype. The two alleles don’t blend, but are rather both present in the offspring. Examples:-1. Checkered Chickens 2. Roan Horses 3. Roan Cows 4. Variegated flower Some Other Example: Human Blood Groups Sickle Cell Anaemia

4. CODOMINANCE- in - Checkered chickens BB = Black chickens WW= White chickens BW= Checkered chickens

5. CODOMINANCE in -Roan Horse Chestnut Horse White Horse Roan Horse

6. CODOMINANCE -in-Roan Cattle White Cattle Brown Cattle

7. CODOMINANCE- in-Variegated Flower In some instances, certain traits are co-dominant. That means that one trait cannot win out over the other from of the trait. In offspring both traits show up equally. In Rhododendrons, Pink is dominant with White. This plant displays co-dominance. Cross a pink rhododendron P with a White rhododendron W

8. CODOMINANCE IN HUMANS (HUMAN BLOOD) ABO BLOOD TYPE Que : Complete a cross with a father & mother that both have type AB blood. What % of their offspring could receive each blood group? This results in four blood types: A, B, O and the  BLENDED  AB When two alleles are BOTH expressed together AB is co-dominant trait

9. CODOMINANCE- in- Sickle Cell Anaemia In co-dominance, heterozygotes have their own phenotype. This gives rise to different proportions amongst offspring of some genetic crosses Normal haemoglobin is (RR), Sickle Cell shaped blood cells (SS) People who are carries (Heterozygous) for the disease there is a mixture of both normal and sickle cells. Co-dominance caused by an abnormal Haemoglobin, the protein that RBCs use to carry Oxygen.

10. CODOMINANCE –in- Sickle Cell Anaemia Show the cross between an individual with sickle-cell anaemia and another who is a carrier but not sick. Genotypes: NS= 2 SS=2 Ratio= 1:1 Phenotypes: Carrier= 2 Sick=2 Ratio= 1:1

11. DIFFERENCES BETWEEN INCOMPLETE DOMINANCE & CODOMINANCE SN INCOMPLETE DOMINANCE CODOMINANCE 1. Effect of one of the two allele is more conspicuous. Effect of both the alleles are equally conspicuous 2. It produces a fine mixture of the expression of two alleles. There is no mixing of the expression of two alleles. 3. The effect in hybrid is intermediate of the two alleles. Both the alleles produce their effect independently. 4. The expressed phenomenon is new. It has no allele of its own. The expressed phenotype is combination of two phenotypes and their alleles. 5. The incomplete dominant alleles has quantitative equivalent effect. Ex.- Mirabilis Jalapa, Antirhinum majus . The quantitative effect is absent. Example:-A & B Blood group alleles of human, Roan character in cattle.

12. THINK ABOUT INCOMPLETE DOMINANCE & CODOMINANCE Let’s say there are two alleles for the hair colour trait- RED & BLUE Que. What would be the resulting phenotype of a heterozygous pair. If the alleles showed Incomplete Dominance? Que. What would be the resulting phenotype of a heterozygous pair. If the alleles showed Co- Dominance? A) RED A) RED B) BLUE B) BLUE C) PURPLE C) PURPLE D) RED and BLUE Patches D) RED and BLUE Patches The result of incomplete dominance leads to ternary phenotype ternary genotype intermediate phenotype intermediate genotype In case of co-dominance product is ____ a ) Produced from both the alleles b) Produced from one allele c) Incompletely produced from both alleles d) None are functional

13. CONCLUSION ON INCOMPLETE DOMINANCE & CODOMINANCE In incomplete dominance- It is clear that the dominant allele does not supress the recessive allele and thus BLENDING occurs and an intermediate is formed. It is a non Mendelian traits In co-dominance:- The case is not that like as incomplete dominance, here BLENDING does not occur rather an another product is formed which is neither recessive nor dominant and contains gametes of both dominant and recessive gametes and all the products come in proportion. Some MCQS are:- A pink flower is an example of __________ a) Multiple alleles, b) Co-dominance, c) Incomplete dominance 2. A Checkered Chicken is an example of ____________ a) Co-dominance, b) Multiple alleles, c) Incomplete dominance 3. Blood type is an example of _____________ a) Multiple alleles, b) Co-dominance, c) Incomplete dominance 4. True/False: Fathers can pass sex linked traits like colour blindness on to their sons. 5. True /False: A blood has the genotypes AA and AO.

14. 1. Both alleles are fully expressed  Complete dominance  Partial dominance   Codominance 2. Exhibits Mendelian pattern   Complete dominance  Partial dominance   Codominance 3. Which is not an example of codominance ?  Black and white coat  White-spotted red flower  Pink flower 4. A variant of a gene   Allele  Chromosome  Nucleotide 5. It means the alleles occupying the same locus are different  Genotype  Homozygous   Heterozygous 6. The gene by which the ABO blood group system is controlled is classified as gene 'I' gene A' gene 'B' gene 'O' 7. The kind of situation in which alleles of gene pair are expressed completely by themselves is called segregation dependent assortment co-dominance dominance 8. The examples of deviations from laws of inheritance proposed by Mendel includes evolutionary dominance only incomplete dominance only co-dominance evolutionary and incomplete dominance 9. The situation in which no allele is dominant over the other is called assorted dominance segregated dominance complete dominance incomplete dominance

15. RNC