Textbook Question
A base substitution for an enzyme replaces leucine (a nonpolar amino acid) with alanine. Why does this change in amino acids have little effect on the biological activity of the enzyme?
Ch.11 Nucleic Acids Big Molecules with a Big Role
Frost4th EditionGeneral, Organic and Biological ChemistryISBN: 9780134988696
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Table of contents
- Ch.4 Introduction to Organic Compounds75
- Ch.5 Chemical Reactions19
- Ch.6 Carbohydrates Life's Sweet Molecules62
- Ch.7 States of Matter and Their Attractive Forces8
- Ch.8 Solution Chemistry Sugar and Water Do Mix4
- Ch.10 Proteins Workers of the Cell89
- Ch.11 Nucleic Acids Big Molecules with a Big Role69
- Ch.12 Food as Fuel An Overview of Metabolism65
Frost4th EditionGeneral, Organic and Biological ChemistryISBN: 9780134988696Not the one you use?Change textbook
Chapter 7, Problem 84a
Oxytocin is a small peptide hormone involved in the process of birthing and lactation. It contains the nine amino acids shown.
CYIQNCPLG
a. How many nucleotides would be found in the mRNA for this protein?
Verified step by step guidance1
Step 1: Understand the relationship between amino acids and codons. Each amino acid in a protein is encoded by a sequence of three nucleotides in the mRNA, known as a codon.
Step 2: Count the number of amino acids in the given peptide sequence. The sequence provided is 'CYIQNCPLG', which contains 9 amino acids.
Step 3: Multiply the number of amino acids by the number of nucleotides per codon. Since each amino acid corresponds to a codon of 3 nucleotides, multiply 9 (amino acids) by 3 (nucleotides per codon).
Step 4: Consider the start codon. In mRNA, the translation process begins with a start codon (AUG), which adds 3 additional nucleotides to the total count.
Step 5: Add the total nucleotides from the amino acids to the nucleotides from the start codon to determine the total number of nucleotides in the mRNA for this protein.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Amino Acids and Codons
Amino acids are the building blocks of proteins, and each amino acid is encoded by a sequence of three nucleotides known as a codon. In the case of oxytocin, which consists of nine amino acids, the corresponding mRNA will have a sequence of codons that directly translate to these amino acids.
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Amino Acid Catabolism: Amino Group Example 2
mRNA Synthesis
mRNA, or messenger RNA, is synthesized during the process of transcription, where a DNA template is used to create a complementary RNA strand. The length of the mRNA is determined by the number of codons needed to encode the entire protein, which is directly related to the number of amino acids in the protein.
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Nucleotide Count in mRNA
Since each codon consists of three nucleotides, the total number of nucleotides in the mRNA can be calculated by multiplying the number of amino acids by three. For oxytocin, with nine amino acids, the mRNA would contain 27 nucleotides, as each amino acid corresponds to one codon of three nucleotides.
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Related Practice
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Textbook Question
Alpha-melanocyte stimulating hormone (α-MSH) is a 13-amino-acid peptide hormone responsible for pigmentations in hair and skin. Its peptide sequence is shown.
SYSMQHFRWGKPV
a. How many nucleotides would be found in the mRNA for this protein?
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Textbook Question
Alpha-melanocyte stimulating hormone (α-MSH) is a 13-amino-acid peptide hormone responsible for pigmentations in hair and skin. Its peptide sequence is shown.
SYSMQHFRWGKPV
b. Suggest an mRNA sequence for the peptide. Show the 5' and 3' ends.
574
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Textbook Question
Alpha-melanocyte stimulating hormone (α-MSH) is a 13-amino-acid peptide hormone responsible for pigmentations in hair and skin. Its peptide sequence is shown.
SYSMQHFRWGKPV
c. Suggest a complementary template DNA sequence based on the mRNA sequence suggested in part b.
551
views