Question

missense mutations

1. cftr g551d mutations - this mutation occurs in about 5% of cf patients. compare the two amino acid sequences of a normal and mutant version of the gene.

normal dna: cct cca gtt gct
mutant: cct cta gtt gct
both have columns for mrna and amino acids

Explanation:

Step1: Transcribe Normal DNA to mRNA

Pair DNA bases to mRNA: A→U, T→A, C→G, G→C.
Normal DNA: CCT CCA GTT GCT
Normal mRNA: $GGU\ GGU\ CAA\ CGA$

Step2: Translate Normal mRNA to amino acids

Use codon table to match mRNA to amino acids.
Normal amino acids: Glycine (Gly) - Glycine (Gly) - Glutamine (Gln) - Arginine (Arg)

Step3: Transcribe Mutant DNA to mRNA

Pair DNA bases to mRNA: A→U, T→A, C→G, G→C.
Mutant DNA: CCT CTA GTT GCT
Mutant mRNA: $GGU\ GAU\ CAA\ CGA$

Step4: Translate Mutant mRNA to amino acids

Use codon table to match mRNA to amino acids.
Mutant amino acids: Glycine (Gly) - Aspartic Acid (Asp) - Glutamine (Gln) - Arginine (Arg)

Answer:

Normal DNA	CCT CCA GTT GCT
Amino Acids	Gly - Gly - Gln - Arg

Mutant	CCT CTA GTT GCT
Amino Acids	Gly - Asp - Gln - Arg

The mutation changes the second amino acid from glycine (Gly) to aspartic acid (Asp).