When dna is copied, sometimes a new, incorrect base-pairing appears within the structure of a new dna molecule replacing original base pairs. this mistake is called a base-pair a) deletion. b) insertion. c) institution. d) substitution.

D (substitution)

Explanation:

Base pair substitution is a kind of mutation that may arise during replication or recombination. It involves the replacement of a single nucleotide base with another in a DNA or RNA molecule. Single base substitutions are called Point mutation.

Point mutations (single base pair substitution) that occur in DNA sequences encoding proteins are either:

1. Silent; where a synonymous codon with the original is generated i.e. the generated codon encodes the same protein as the original codon. Hence, the sequence is not changed and has no adverse effect on the organism.

2. Missense; When base substitution results in the generation of a codon that specifies a different amino acid and hence leads to a different polypeptide sequence

3. Nonsense; When a base substitution results in a stop codon ultimately truncating translation and most likely leading to a nonfunctional protein.