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Ch.10 Proteins Workers of the Cell
Frost - General, Organic and Biological Chemistry 4th Edition
Frost4th EditionGeneral, Organic and Biological ChemistryISBN: 9780134988696Not the one you use?Change textbook
All textbooksFrost 4th EditionCh.10 Proteins Workers of the CellProblem 30b
Chapter 6, Problem 30b

Myoglobin is a protein containing 153 amino acids. Approximately half of the amino acids in myoglobin have polar side chains.
b. Where would you expect the nonpolar side chains to be?

Verified step by step guidance
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Understand the structure of proteins: Proteins like myoglobin have a complex three-dimensional structure that is crucial for their function. This structure is determined by the sequence of amino acids and their interactions.
Recognize the nature of side chains: Amino acids have side chains that can be polar or nonpolar. Polar side chains are hydrophilic (water-attracting), while nonpolar side chains are hydrophobic (water-repelling).
Consider the environment of myoglobin: Myoglobin is a globular protein that functions in an aqueous environment, such as the cytoplasm of cells.
Apply the principle of hydrophobic interactions: In aqueous environments, nonpolar side chains tend to cluster together away from water, often found in the interior of the protein structure.
Conclude the location of nonpolar side chains: Based on the above principles, you would expect the nonpolar side chains of myoglobin to be located in the interior of the protein, away from the aqueous environment.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Protein Structure

Proteins are composed of long chains of amino acids that fold into specific three-dimensional shapes. The structure of a protein is crucial for its function, and it is typically organized into four levels: primary, secondary, tertiary, and quaternary. Understanding how these structures relate to the properties of amino acids, such as polarity, is essential for predicting the behavior of proteins in different environments.
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Polarity of Amino Acids

Amino acids can be classified based on the properties of their side chains, particularly their polarity. Polar amino acids have side chains that can form hydrogen bonds with water, making them hydrophilic, while nonpolar amino acids have hydrophobic side chains that do not interact favorably with water. This distinction influences how proteins fold and where different types of amino acids are located within the protein structure.
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Hydrophobic Effect

The hydrophobic effect is a key driving force in protein folding, where nonpolar side chains tend to aggregate away from the aqueous environment to minimize their exposure to water. This phenomenon leads to the clustering of nonpolar amino acids in the interior of the protein, while polar amino acids are often found on the surface, interacting with the surrounding water. Understanding this effect is crucial for predicting the spatial arrangement of amino acids in proteins like myoglobin.
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Related Practice
Textbook Question

Myoglobin is a protein containing 153 amino acids. Approximately half of the amino acids in myoglobin have polar side chains.

a. Where would you expect these amino acid side chains to be located in the tertiary structure of the protein?

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Textbook Question

Determine whether each of the following statements describes the primary, secondary, tertiary, or quaternary structure of a protein.

d. Amino acids react in a condensation reaction to form a peptide bond.

Textbook Question

Determine whether each of the following statements describes the primary, secondary, tertiary, or quaternary structure of a protein.

b. Hydrogen bonds form between adjacent segments of the backbone of the same protein to form a “folded-fan” structure.

Textbook Question

Identify each of the following statements as characteristic of protein denaturation or protein hydrolysis. 

a. Milk curdles when lemon juice is added to it.

Textbook Question

List the type of attractive force disrupted and the level of protein structure changed by the following denaturing treatments:

a. adding salt to soy milk to make tofu

Textbook Question

Identify each of the following statements as characteristic of protein denaturation or protein hydrolysis. 

b. A protein breaks up into amino acid fragments.