Genetics Student Response

Original DNA Strand:

3'-T ACCCTTTAGCCACT-5'

Transcription (base sequence of RNA):

3'-A UGGGAAAUCGGUGA-5'

Translation (amino acid sequence):

Met -- Gly -- Asn -- His -- Arg -- STOP

Mutated gene sequence one:

3'-T ACGCTTTAGCCATT-5'

Transcription (base sequence of RNA):

3'-A UGCGAAAUCGGUAA-5'

Translation (amino acid sequence):

Met -- Arg -- Asn -- His -- Arg -- STOP

Mutated gene sequence two:

3'-T AACCTTTACTAGGCACT-5'

Transcription (base sequence of RNA):

3'-A UUGGAAAUGAUCCGUGA-5'

Translation (amino acid sequence):

Ile -- Gly -- Asn -- Asp -- Pro-STOP

What is the significance of the first and last codons of an mRNA transcript?

The first codon ("Met") indicates the beginning of the transcription sequence. The last codon indicates the end of a protein sequence, which stops transcription.

Explanation:

Each protein sequence is coded with a starting and ending point, to indicate the length and type of the protein according to the sequence transcribed from the DNA template to the mRNA.

What meaning do these mRNA codons have for protein synthesis?

Each codon consists of three bases, which stand for a particular amino acid. A string of mRNA with groups of amino acids become grouped together and the combination thereof leads to...

tRNA recognizes the codons and duly provides the appropriate amino acid (for example, GGA stands for amino acid "Gly." rRNA then creates the protein out of the combination of amino acids.
Did the two mutations result in a change in the final proteins? If so, describe the change.

Both mutations have altered the final proteins. The first mutation changed the protein itself, while the second mutation disabled the protein entirely.

Response / explanation:

One letter change can completely alter an amino acid sequence. The first mutation changed a codon, which altered the second amino acid, thereby changing the protein to be made. Because the second mutation does not have the starting codon (AUG for "Met"), then the tRNA does not start translating the respective sequence.

In general, why might a change in amino acid sequence affect protein function?

The synthesis of proteins is determined by the string of amino acids found in each sequence. By changing a specific amino acid in a protein, there is the chance that the protein itself is altered, perhaps in such a way that it no longer performs the functions that it is labeled to do.

Explanation:

The body relies on proteins to bind, cut, and maintain the activities that keep the body going. A breakdown in a particular protein might spell negative effects. For example, somebody who is…