Question

a point mutation can be completely harmless   or it can result in the death if a cell or organism. Explain why these types of mutation can have such varying effects please condense answer as much as possible

Answer 1

Since you need a condensed answer, so I'll try to be short and precise as much as possible while providing accurate explanation.

The extent of damage caused by point mutation majorly depends upon its location. If point mutation occurs in non-coding region (introns), then the effect of this point mutation is entirely harmless, except for promoter region and splice sites. If the point mutation takes place there, then the expression of gene is changed. Otherwise, point mutations in non-coding regions are usually harmless.

On the other hand, if the point mutation takes place in coding sequences (exons), then just by altering one nucleotide base, its coded amino acid will be changed, due to change in codon. If this coded amino acid gets changed, then the resultant protein will be ultimately changed. The protein will be entirely different, which will severely affect the functionality of the organism, due to different structure and functionality. Hence point mutations in coding regions are generally lethal.

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