In recent years, DNA sequences (nucleotide sequence) of mt-DNA and Y chromosomes were considered for the study of human evolution, because : -
A
They are small, and therefore, easy to study
B
They are uniparental in origin and do not take part in recombination
C
Their structure is known in greater detail
D
They can be studied from the samples of fossil remains
The answer is B.
Solution
Mitochondrial DNA is inherited only from the mother (maternal inheritance), and most of the Y chromosome is inherited only from the father to sons. So both are uniparental in origin. They do not undergo recombination (mtDNA has no partner, and most of the Y chromosome does not cross over with the X). So the sequences pass unchanged from generation to generation except for mutations, which accumulate at a roughly steady rate. Comparing them among populations lets scientists trace maternal and paternal lineages back in time (e.g. the 'Mitochondrial Eve' and 'Y-chromosome Adam' studies). So they are used because they are uniparental in origin and do not take part in recombination.
ConceptUniparental markers in human evolution
Evolution in past papers
143 questions from this chapter have appeared across 27 exam years.
