Tetrad Analysis You should be able to explain and you should know examples of these: 1) Incomplete dominance 2) dominant negative 3) co-dominance, 4) pleotropic effect 5) epistasis 6) suppressors 7) developmental noise 8) norm of reaction (phenotypic plasticity). 9) You should be able to explain the biochemistry of ABO blood type and epistasis between h and I genes. Solution 1) incompletes dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely exprssed over its paired allele. It leads to the formation of a third phenotype in which the expressed physical trait is a combination of phenotypes of noth alleles.Example is a flower that is pink in colour due to cross pollination between a red and a white flower,when neither the white or red alleles are dominant. 2. dominant negative is used to describe a gene that has a dominant effect similar to that described genetically,one copy of the gene gives a mutant phenotype effect and a negative copy and the negative effect in that it prevents.For example a protein that functional as a dimer.A mutation that removes the functional domain but reatins the dimerization domain would cause a dominant negatice phenotype because some part of the dimer would be missing functional domains. 3. Co dominance is a type of dominance in which both the alleles in a gene pair in a heterozygote are fully expressed. The human ABO blood groups provide an example of co dominance. 4. Pleiotropric effect is to have multiple effects from the same gene.Example , marfan gene is pleiotropic .it had many effects such as long fingers and toes,disslocation of the lens of the eye. 5.epistasis is a phenomena in which the effect of one gene is dependant on the prsesnce of one or more modifier genes.In case of dominant epistasis there is complete dominance at both gene pairs however when one gene is dominant it hides the phenotype of the other gene. in recessive epistasis recessive genes at one locus mask the phenotypic expression of other gene locus. example, the gene for male pattern baldness is epistatic to the gene for red hair..

1. Tetrad Analysis
You should be able to explain and you should know examples of these:
1) Incomplete dominance
2) dominant negative
3) co-dominance,
4) pleotropic effect
5) epistasis
6) suppressors
7) developmental noise
8) norm of reaction (phenotypic plasticity).
9) You should be able to explain the biochemistry of ABO blood type and epistasis between h
and I genes.
Solution
1) incompletes dominance is a form of intermediate inheritance in which one allele for a specific
trait is not completely exprssed over its paired allele. It leads to the formation of a third
phenotype in which the expressed physical trait is a combination of phenotypes of noth
alleles.Example is a flower that is pink in colour due to cross pollination between a red and a
white flower,when neither the white or red alleles are dominant.
2. dominant negative is used to describe a gene that has a dominant effect similar to that
described genetically,one copy of the gene gives a mutant phenotype effect and a negative copy
and the negative effect in that it prevents.For example a protein that functional as a dimer.A
mutation that removes the functional domain but reatins the dimerization domain would cause a
dominant negatice phenotype because some part of the dimer would be missing functional
domains.
3. Co dominance is a type of dominance in which both the alleles in a gene pair in a heterozygote
are fully expressed. The human ABO blood groups provide an example of co dominance.
4. Pleiotropric effect is to have multiple effects from the same gene.Example , marfan gene is
pleiotropic .it had many effects such as long fingers and toes,disslocation of the lens of the eye.
5.epistasis is a phenomena in which the effect of one gene is dependant on the prsesnce of one or
more modifier genes.In case of dominant epistasis there is complete dominance at both gene
pairs however when one gene is dominant it hides the phenotype of the other gene.
in recessive epistasis recessive genes at one locus mask the phenotypic expression of other gene
locus.

2. example, the gene for male pattern baldness is epistatic to the gene for red hair.