Let\'s use the letters \"R\" and \"r\" to represent a recessive mutation. R repr

Question

Let's use the letters "R" and "r" to represent a recessive mutation. R represents t represents the mutant allele. Fill in the missing phenotypes as either "a 3. ffected" or "unaffected for each case. Autosomal recessive traits X-linked recessive traits Females Males genotype phenotype genotype phenotype genotype phenotype RY rY Rr Let's use the letters "D" and "d" to represent a dominant mutation. D represents the mutant allele and d represents the nonmutant allele. Fill in the missing phenotypes as either "affected" or "unaffected" for each case. 4. X-linked dominant traits Autosomal dominant traits Females Renotype phenotype genotype phenotype genotype phenotype Males DY dY Dd Dd Is the relationship between genotype and phenotype always the same for different kinds of traits? Why or why not?

Explanation / Answer

Recessive mutations are those mutations where the mutation in both copies of gene result in mutant phenotype.Mutation in one copy of gene(one allele)will not effect the phenotype because of presence of one normal,nonmutant allele.

Dominant mutations are those where mutation in just onw copy of gene will change the phenotype from normal to mutant one because mutation in one copy of gene is enough to bring the changes in phenotype.

Now if we carefully observe the cases we can conclude the outcomes-

1.autosomal recessive(mutation in both copies of gene will result in affected phenotype)

So RR-unaffected(both normal copies)

Rr-unaffected(one normal copy is enough to maintain normal phenotype)

rr-affected(both copies got mutated,will result in mutant phenotype)

2.X linked recessive(both copies of genes on X chromosomes should be mutated to change the normal phenotype,but in males single X chromosome is there so mutation in gene on chromosome will change the phenotype)

So for females:RR-unaffected

Rr-unaffected(females have 2 X chromosomes)

rr-affected

For males:

RY-unaffected

rY-affected(no normal copy of gene)

3.autosomal dominant(mutation in single copy of gene is enough to change the phenotype)D-mutant,d-normal allele

DD-affected

Dd-affected

dd-unaffected

4.X linked dominant(change in single copy is enough to alter the phenotype)

Females-

DD-affected

Dd-affected

dd-unaffected(both alleles are nonmutant)

For males-

DY-affected

dY-unaffected

Genotype and phenotypes are not same for different kind of traits.

Genotype refer to the genetic makeup while phenotype refer to the morphological appearance.

Phenotype depends on the inheritance of alleles,their expression characteristics as in case of dominant and recessive mutations.

For example in case of autosomal recessive inheritance RR is unaffected so the Rr but their genotypes are different.

If we talk about autosomal dominant condition then DD is affected so the Dd but their genotypes are different.

I hope this answer will clear your doubt.

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