Textbook Question
Identify some differences between the following pairs:
b. complete and incomplete proteins
Ch.10 Proteins Workers of the Cell
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 6, Problem 65b
Consider the amino acids glycine, proline, and lysine.
b. Using three-letter abbreviations for the amino acids, give the sequence for each of the possible tripeptides.
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Identify the three amino acids given in the problem: glycine (Gly), proline (Pro), and lysine (Lys). These are the building blocks for the tripeptides.
Understand that a tripeptide is a sequence of three amino acids linked together by peptide bonds. The order of the amino acids in the sequence matters, so each unique arrangement represents a different tripeptide.
Determine the total number of possible sequences. Since there are three amino acids and each position in the tripeptide can be occupied by any of the three amino acids, the number of permutations is calculated as 3! (3 factorial), which equals 6.
List all possible sequences using the three-letter abbreviations for the amino acids. The sequences are: Gly-Pro-Lys, Gly-Lys-Pro, Pro-Gly-Lys, Pro-Lys-Gly, Lys-Gly-Pro, and Lys-Pro-Gly.
Verify that all six sequences are unique and that no sequence is repeated. This ensures that all possible tripeptides have been accounted for.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Amino Acids
Amino acids are organic compounds that serve as the building blocks of proteins. Each amino acid has a specific structure, consisting of a central carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a variable side chain (R group) that determines its properties. Glycine (Gly), proline (Pro), and lysine (Lys) are three distinct amino acids, each with unique characteristics that influence protein structure and function.
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Tripeptides
Tripeptides are molecules formed by the linkage of three amino acids through peptide bonds. The sequence in which the amino acids are arranged is crucial, as it determines the tripeptide's properties and biological function. The order of amino acids can vary, leading to different tripeptides even if the same amino acids are used, highlighting the importance of sequence in protein chemistry.
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Three-Letter Abbreviations
Three-letter abbreviations are standardized codes used to represent amino acids in a concise manner. For example, glycine is abbreviated as 'Gly', proline as 'Pro', and lysine as 'Lys'. These abbreviations facilitate easier communication and notation in biochemistry, especially when discussing sequences of amino acids in proteins or peptides.
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Related Practice
Textbook Question
Give the name and three-letter abbreviation for the amino acid described by each of the following:
c. the polar amino acid with a sulfur atom in its side chain
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Textbook Question
Would you expect to find this segment at the center or on the surface of a globular protein? Why?
Textbook Question
Name the covalent bond that helps to stabilize the tertiary structure of a protein.
Textbook Question
Draw the structure of the possible dipeptides formed from one alanine combining with one cysteine.
Textbook Question
Aspartame, which is commonly known as NutraSweet™, contains the following dipeptide:
d. Draw the structure of the isomer of this dipeptide where the C-terminal and N-terminal amino acids are switched.