how could one change in a dna molecule alter the formation of a translated protein?

Question

an ex: would be the difference between normal and sick-cell hemoglobin)

Answer 1

if dna is rightly copied into rna, then a different amino acid will be produced then what should be in the protein

Answer 2

Changing one base could change the entire protein or not even change one amino acid.

A substitution mutation changes one nucleotide into another. But since there are several codons for a single amino acid, sometimes the protein that is translated is 100% the same.

Sometimes it codes for a different amino acid. This could have serious effects or not make much of an effect at all. It all depends on how much the new amino acid alters the shape of the protein. If a hydrophobic amino acid is replaced by a neutral or hydrophilic it would make the error more serious.

Sometimes a substitution mutation creates new stop codon. This is serious because the ribosome would stop translating at this point. The protein would only be partially made.

If the DNA molecule lost three bases or added three new bases (and these happened between existing codons) then a new amino acid is added or one is lost. This again could definitely change the shape of the protein and therefore its function.

Lastly, if one or two bases are added or lost it would cause a frameshift mutation. This is very serious. It would cause the entire sequence of amino acids to change. It ofsets the entire sequence of codons, creating a recipe for a totally different protein.

Answer 3

If the one change is a substitution, putting in the wrong base instead of the right one, then the codon with that base may call for a different amino acid. If you change an amino acid, you change the protein.

Think of it like changing one letter in a word. You could make a new word, or you could make something that makes no sense at all.

Original sentence:
The bad man ran off.

Problems:
The bad mar ran off.
The bac man ran off.
Hhe bad man ran off.

All of these have "fatal" problems as far as sentences go! They don't make sense any more.