Dominance in plants .types of dominance with examples

Dominance in plants
Types of dominance
Complete dominance
Incomplete dominance
With examples

1. DOMINANCE PRESENTED BY : SYEDA FATIMA PRESENTED TO : DR. SARWAT RAHIM

2. DEFINITION In  genetics,  dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome.

3. TYPES OF VARIANTS ( ALLELES ) DOMINANT ALLELE The allele that is fully expressed is called the dominant allele RECESSIVE ALLELE The masked allele is called the recessive allele.

4. Key concept of Mendalian i nheritence Dominance is a key concept in Mendelian inheritance and classical genetics . Letters and Punnett squares are used to demonstrate the principles of dominance in teaching. the upper-case letters are used to denote dominant alleles and lower-case letters are used for recessive alleles.

5. example An often quoted example of dominance is the inheritance of seed shape in peas . Peas may be: round “associated with allele R” wrinkled “associated with allele”

6. Background history Mendel, "The Father of Genetics", promulgated the idea of dominance in the 1860s. However, it was not widely known until the early twentieth century.

7. Continue…… Mendel did not use the terms gene, allele, phenotype, genotype, homozygote, and heterozygote, all of which were introduced later . He did introduce the notation of capital and lowercase letters for dominant and recessive alleles, respectively, still in use today.

8. TYPES OF DOMINANCE .

9. Complete dominance

10. incomplete dominance

11. Co-dominance

12. Complete dominance Complete dominance is a condition where the dominant allele completely masks the effect of the recessive allele. In this type , two types of alleles are present: Dominant allele Recessive allele

13. Complete dominance: example For instance, for an individual carrying two alleles that are both dominant (e.g. AA), the trait that they represent will be expressed . But if the individual carries two alleles in a manner that one is dominant and the other one is recessive, (e.g. Aa), the dominant allele will be expressed while the recessive allele will be suppressed. Hence , the heterozygote (Aa) will have the same phenotype as that of the dominant homozygote (AA). This condition is called complete dominance.

14. Key point for recessive allele recessive allele's trait is hidden by the dominant allele and only shows its effect in the absence of a dominant allele (paired with another recessive allele). Represented by a lowercase letter (e.g., a).

15. incomplete dominance Incomplete dominance pertains to the genetic phenomenon in which the distinct gene products from the two codominant alleles in a heterozygote blend to form a phenotype intermediate between those of the two homozygotes . Also known as partial dominance.

16. incomplete dominance : example Let’s understand the incomplete dominance with the example of Snapdragon flower ( Antirrhinum sp ). true-breeding red (RR) and white ( rr ) coloured flowers of snapdragon were crossed. The F1­ generation produced a pink coloured flower with Rr pair of alleles.

17. incomplete dominance : example In Humans The child of parents each with curly hair and straight hair will always have wavy hair. In Other Animals When the rabbits with long and short furs are bred, the offsprings produced will have medium fur length.

18. Human wavy hair

19. Co- dominance Codominance, as it relates to genetics, refers to a type of inheritance in which two versions (alleles) of the same gene are expressed separately to yield different traits in an individual . It is due to the blending of alleles.

20. Co- dominance : examples

21. Thank you .