BackShown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.
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Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr
Mutant 1: Met-Trp
Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr
Mutant 3: Met-Cys-Ile-Val-Val-Val-Gln-His _
Use this information to answer the following questions:
The wild-type RNA consists of nine triplets. What is the role of the ninth triplet?
Shown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.
___________________________________________________
Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr
Mutant 1: Met-Trp
Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr
Mutant 3: Met-Cys-Ile-Val-Val-Val-Gln-His _
Use this information to answer the following questions:
For each mutant protein, determine the specific ribonucleotide change that led to its synthesis.
Shown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.
___________________________________________________
Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr
Mutant 1: Met-Trp
Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr
Mutant 3: Met-Cys-Ile-Val-Val-Val-Gln-His _
Use this information to answer the following questions:
Another mutation (mutant 4) is isolated. Its amino acid sequence is unchanged from wild type, but the mutant cells produce abnormally low amounts of the wild-type proteins. As specifically as you can, predict where this mutation exists in the gene.
Shown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.
___________________________________________________
Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr
Mutant 1: Met-Trp
Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr
Mutant 3: Met-Cys-Ile-Val-Val-Val-Gln-His _
Use this information to answer the following questions:
Of the first eight wild-type triplets, which, if any, can you determine specifically from an analysis of the mutant proteins? In each case, explain why or why not.
A DNA sequence encoding a five-amino acid polypeptide is given below.
...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...
...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...
What is the function of the Shine–Dalgarno sequence?
A DNA sequence encoding a five-amino acid polypeptide is given below.
...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...
...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...
Assuming the sequence above is a bacterial gene, identify the region encoding the Shine–Dalgarno sequence.
A DNA sequence encoding a five-amino acid polypeptide is given below.
...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...
...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...
Give the polypeptide sequence, and identify the N terminus and C terminus.
A DNA sequence encoding a five-amino acid polypeptide is given below.
...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...
...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...
Give the sequence and polarity of the mRNA encoding the polypeptide.
A DNA sequence encoding a five-amino acid polypeptide is given below.
...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...
...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...
Locate the sequence encoding the five amino acids of the polypeptide, and identify the template and coding strands of DNA.
The genetic code is degenerate. Amino acids are encoded by either 1, 2, 3, 4, or 6 triplet codons (see Figure 13.7). An interesting question is whether the number of triplet codes for a given amino acid is in any way correlated with the frequency with which that amino acid appears in proteins. That is, is the genetic code optimized for its intended use? Some approximations of the frequency of appearance of nine amino acids in proteins in E. coli are given in the following:
Amino Acid Percentage
Met 2
Cys 2
Gln 5
Pro 5
Arg 5
Ile 6
Glu 7
Ala 8
Leu 10
How would you proceed with your analysis if you wanted to pursue this problem further?
The genetic code is degenerate. Amino acids are encoded by either 1, 2, 3, 4, or 6 triplet codons (see Figure 13.7). An interesting question is whether the number of triplet codes for a given amino acid is in any way correlated with the frequency with which that amino acid appears in proteins. That is, is the genetic code optimized for its intended use? Some approximations of the frequency of appearance of nine amino acids in proteins in E. coli are given in the following:
Amino Acid Percentage
Met 2
Cys 2
Gln 5
Pro 5
Arg 5
Ile 6
Glu 7
Ala 8
Leu 10
Analyze your data to determine what, if any, correlations can be drawn between the relative frequency of amino acids making up proteins and the number of codons for each. Write a paragraph that states your specific and general conclusions.
The genetic code is degenerate. Amino acids are encoded by either 1, 2, 3, 4, or 6 triplet codons (see Figure 13.7). An interesting question is whether the number of triplet codes for a given amino acid is in any way correlated with the frequency with which that amino acid appears in proteins. That is, is the genetic code optimized for its intended use? Some approximations of the frequency of appearance of nine amino acids in proteins in E. coli are given in the following:
Amino Acid Percentage
Met 2
Cys 2
Gln 5
Pro 5
Arg 5
Ile 6
Glu 7
Ala 8
Leu 10
Devise a way to graphically compare the two sets of information (data).
The genetic code is degenerate. Amino acids are encoded by either 1, 2, 3, 4, or 6 triplet codons (see Figure 13.7). An interesting question is whether the number of triplet codes for a given amino acid is in any way correlated with the frequency with which that amino acid appears in proteins. That is, is the genetic code optimized for its intended use? Some approximations of the frequency of appearance of nine amino acids in proteins in E. coli are given in the following:
Amino Acid Percentage
Met 2
Cys 2
Gln 5
Pro 5
Arg 5
Ile 6
Glu 7
Ala 8
Leu 10
Determine how many triplets encode each amino acid.
A portion of the coding strand of DNA for a gene has the sequence
5′-...GGAGAGAATGAATCT...-3′
Write out the template DNA strand sequence and polarity as well as the mRNA sequence and polarity for this gene segment.
A portion of the coding strand of DNA for a gene has the sequence
5′-...GGAGAGAATGAATCT...-3′
Assuming the mRNA is in the correct reading frame, write the amino acid sequence of the polypeptide using three-letter abbreviations and, separately, the amino acid sequence using one-letter abbreviations.