Question

Explain cytoplasmic inheritance with the example of limnea.​

Answer 1

Answer:

The colour of the offspring (Pale, green, pale-green and variegated) is determined by the egg and what the egg produces, depends upon the characters of its plastids. Since plastids are found in the cytoplasm, we can cite this as an example of cytoplasmic inheritance.

Answer 2

Cytoplasmic inheritance means inheritance of  extra-chromosomal genes present in cytoplasm. Maternal inheritance is one type of cytoplasmic inheritance

Explanation:

• offspring inherit most of the cytoplasm from her mother, so they inherit cytoplasmic organelles present in cytoplasm from mother.
• father does not contribute any cytoplasm, thus no cytoplasmic organelles(mitochondria, chloroplast)
• hence such inheritance is called maternal inheritance in which offsprings inherit mitochondrial gene from their mother.
• Shell coiling in Limnaea is an example of maternal inheritance.
• Two type of shell coiling is found: Dextral and Sinistral
• Dextral gene is controlled by D allele and sinistral gene is controlled by d allele.
• If the mother is Dd(dextral) then all the offspring will have dextral coiling regardless of their genotype i.e. if offspring has dd genotype and mother has Dd genotype then dd offspring will have dextral phenotype instead of sinistral phenotype because mother has dextral phenotype and this coiling pattern is determined by maternal extrachromosomal gene.