Allelic Interactions Flashcards
It is observed only in heterozygotes with dissimilar genes
Allelic Interactions
It is a laboratory method used to separate mixtures of DNA, RNA, or proteins according to molecular size, net charge
Gel Electrophoresis
Types of Allelic Interactions
- Complete Dominance (complete recessiveness)
- Incomplete Dominance
- Codominance
- Allelic Complementation
- Overdominance
- Multiple Alleles
- Complex Dominance
In complete dominance, heterozygotes exhibit _____ trait with ____ genotypic ratio and ____ phenotypic ratio
- dominant
- 1:2:1
- 3:1
Complete Dominance
What allele dictates a protein which actively participates in the development of the trait?
Dominant Alleles
Complete Dominance
What kind of protein that is dictated by the dominant alleles?
A protein that actively participates in the development of the trait
Complete Dominance
What allele dictates a protein with no apparent activity or no protein at all?
Recessive Alleles
Complete Dominance
What kind of protein that is dictated by the recessive alleles?
A kind of protein with no apparent activity or no protein at all
Examples of Complete Dominance
- Brachydactyly (or short fingers)
- Polydactyly
What is a Complete Dominance (complete recessiveness)?
- One allele is completely dominant to another
- Phenotype of the heterozygote is the same as homozygous dominant
- Recessive phenotype is expressed only when the organism is homozygous recessive
- it occurs because neither of the two alleles is completely dominant over the other
- a Gene interaction in which both alleles of a gene at a locus are partially expressed
Incomplete Dominance
Example of Incomplete Dominance
- Incomplete dominance in Carnations (1:2:1 F2)
- Incomplete dominance in Snapdragons
- Petal color in flowers (1:2:1/2:2 F2)
- Roan color in cows
- Sickle cell trait
A phenomenon in which two alleles (different versions of the same gene) are expressed to an equal degree within an organism
Codominance
Example of Codominance
Human ABO Blood group
4 blood phenotypes
- O
- A
- B
- AB
4 blood genotypes
- IA IA or IA i
- IB IB or IB i
- IA IB
- ii
Antibodies present in blood serum
Blood type: A
Anti-B
Antibodies present in blood serum
Blood type: B
Anti-A
Antibodies present in blood serum
Blood type: AB
None
Antibodies present in blood serum
Blood type: O
- Anti-A
- Anti-B
Human ABO Blood group
3 Alleles
- IA
- IB
- I
IA and IB are ____ to i
Dominant
IA and IB are ____ to each other
Codominant
Similar to codominance but the different interaction between two alleles result in the production of a hybrid protein
Allelic Complementation
- also known as heterosis or hybrid vigor
- hybrid is superior to both parents; also 1:2:1 genotypic ratio
- very useful in plant/animal breeding
Overdominance
Overdominance is also knwon as
Heterosis or hybrid vigor
In overdominance, ______ is superior to both parents
Hybrid
Genotypic ratio in Overdominance
1:2:1
Overdominance is very useful in __________
plant/animal breeding
Molecuar explanations for dominance relationships:
COMPLETE DOMINANCE
- Half the amount of gene production produced by homozygote is sufficient (haplosufficient)
- Expression of dominant allele in heterozygote is up-regulated to match the homozygote.
Molecuar explanations for dominance relationships:
INCOMPLETE DOMINANCE
Recessive allele is not expressed in heterozygote
1. Homozygote: 2 doses of a gene product
2. Heterozygote: 1 dose of a gene product
Molecuar explanations for dominance relationships:
CODOMINANCE
Both alleles are expressed resulting in a combined phenotype
Two alleles of the same gene
Multiple Alleles
_____ individuals have only ____ alleles, one on each ______
- Diploid
- two
- chromosome
Example of Multiple Alleles
- ABO blood group
- Drosophila eye color
It is a complex relationship/interaction between two version of a gene
Complex Dominance
