Genes with purely or predominantly matrilineal inheritance without recombination are present in:

Ans. c (Mitochondrial chromosome). (Ref. Harper's Biochemistry 26th ed. 323; Ganong 22nd ed. 11, 27)Inherited mitochondrial disorders are transmitted in a matrilineal fashion; all children from an affected mother will inherit the disease, but it will not be transmitted from an affected father to his children. Heterogeneity in the proportion of mitochondria with and without a mutation is referred to as heteroplasmia and underlies the phenotypic variability that is characteristic of mitochondrial diseases.MITOCHONDRIAL DNA (mtDNA)# It is small circular, double-stranded, and composed of heavy and light chains.# One percent of cellular DNA is in mitochondria.# High mutation rate (5-10 times more than nuclear DNA).# Genetic codes differ slightly from the standard code:- UGA (standard stop codon) is read as Trp.- AG A and AGG (standard codon for Arg) are read as stop codons.Diseases transmitted by mitochondrial inheritance:# Leber's hereditary optic atrophy,# Leigh disease,# Familial progressive external ophthalmoplegia,# MERRF syndrome,# MEALS syndrome,# Succinic dehydrogenase complex-II deficiency and Cytochrome C oxidase complex-IV dt.