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Questions and Answers
Basic amino acids generate negatively charged ions.
Basic amino acids generate negatively charged ions.
False
A dipeptide consists of 3 amino acids linked together.
A dipeptide consists of 3 amino acids linked together.
False
Plants can synthesize all 20 standard amino acids.
Plants can synthesize all 20 standard amino acids.
True
Proteins require a stable, two-dimensional shape to be biologically active.
Proteins require a stable, two-dimensional shape to be biologically active.
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Non-essential amino acids must be obtained through the diet.
Non-essential amino acids must be obtained through the diet.
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The primary structure of a protein refers to the sequence of amino acids in a polypeptide chain.
The primary structure of a protein refers to the sequence of amino acids in a polypeptide chain.
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Essential amino acids in humans include Ala, Asn, and Ser.
Essential amino acids in humans include Ala, Asn, and Ser.
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Polypeptides are considered proteins when they contain more than 50 amino acids.
Polypeptides are considered proteins when they contain more than 50 amino acids.
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Fibrous proteins are typically soluble in water.
Fibrous proteins are typically soluble in water.
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Beta pleated structures are formed by hydrogen bonding between parallel polypeptide chains.
Beta pleated structures are formed by hydrogen bonding between parallel polypeptide chains.
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All proteins possess a quaternary structure.
All proteins possess a quaternary structure.
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Alpha helix structures are stabilized by ionic bonds.
Alpha helix structures are stabilized by ionic bonds.
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Storage proteins are specialized for the transport of nutrients.
Storage proteins are specialized for the transport of nutrients.
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Globular proteins can possess both tertiary and quaternary structures.
Globular proteins can possess both tertiary and quaternary structures.
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Essential amino acids cannot be synthesized by the body and must be obtained through diet.
Essential amino acids cannot be synthesized by the body and must be obtained through diet.
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Contractile proteins are primarily responsible for storing amino acids.
Contractile proteins are primarily responsible for storing amino acids.
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All amino acids have the same basic structure but differ in their side chains.
All amino acids have the same basic structure but differ in their side chains.
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Proteins consist only of polar amino acids.
Proteins consist only of polar amino acids.
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The central carbon atom of an amino acid is referred to as the beta carbon.
The central carbon atom of an amino acid is referred to as the beta carbon.
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Amino acids with non-polar side chains are generally soluble in water.
Amino acids with non-polar side chains are generally soluble in water.
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Each amino acid can be classified into one of four groups based on the properties of their side chains.
Each amino acid can be classified into one of four groups based on the properties of their side chains.
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Polar R group amino acids have the ability to donate electrons.
Polar R group amino acids have the ability to donate electrons.
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Collagen is an example of a structural protein formed primarily from non-polar amino acids.
Collagen is an example of a structural protein formed primarily from non-polar amino acids.
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There are 20 essential amino acids that occur naturally.
There are 20 essential amino acids that occur naturally.
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Study Notes
Amino Acids
- All amino acids share the same basic structure, but differ in their side chains.
- Amino acids are amphoteric, meaning they contain both an acidic carboxyl group (-COOH) and a basic amino group (-NH2).
- Classified into four groups based on the properties of their side chains:
- Polar: Create partial charges but do not receive or donate electrons.
- Non-Polar: Have hydrocarbons as side chains, making them insoluble and non-reactive.
- Positively Charged (Basic R Group):
- Negatively Charged (Acidic R Group):
- Examples of amino acids:
- Non-Polar: Glycine (Gly), Alanine (Ala), Valine (Val), Leucine (Leu), Isoleucine (Ile), Tryptophan (Trp), Proline (Pro), Methionine (Met), Phenylalanine (Phe)
- Polar: Serine (Ser), Asparagine (Asn), Glutamine (Gln), Tyrosine (Tyr), Cysteine (Cys), Threonine (Thr)
- Basic: Lysine (Lys), Arginine (Arg), Histidine (His)
- Acidic: Aspartic acid (Asp), Glutamic acid (Glu)
Protein Structure
- A polypeptide is not yet a protein; proteins require a stable, three-dimensional shape to be biologically active.
- Monomeric proteins: Consist of a single polypeptide chain that folds.
- Multimeric proteins: Consist of two or more polypeptide chains.
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Levels of protein structure:
- Primary Structure: The unique sequence of amino acids in a polypeptide chain, determined by the genetic code in DNA.
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Secondary Structure: The coiling patterns of the polypeptide chain, including:
- Alpha helix structure: Held in shape by hydrogen bonds, resembling a telephone wire.
- Beta pleated structure: Formed by hydrogen bonding between atoms on the polypeptide backbone, providing strength and flexibility.
- Tertiary Structure: The overall 3D shape of a polypeptide, stabilized by hydrogen bonds, ionic bonds, and disulfide bridges.
- Quaternary Structure: The arrangement of multiple polypeptide chains in proteins.
Protein Classification
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By structure:
- Fibrous Proteins: Involved in body structure formation, typically have secondary structures, insoluble in water. Examples: Collagen, myosin, fibrin, keratin.
- Globular Proteins: Have tertiary structures, some have quaternary structures, polypeptide chains are tightly coiled into a sphere. Examples: Globulin, enzymes, antibodies, hormones.
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By composition:
- Simple Proteins: Pure proteins with no other substances. Examples: Fibrous proteins, globular proteins.
- Conjugated Proteins: Composed of a protein portion and a non-protein component (prosthetic group). Further classified based on the properties of the prosthetic group.
Types of Proteins
- Structural Proteins: Found in the hair of mammals, tendons, and ligaments.
- Contractile Proteins: Provide muscular movement.
- Storage Proteins: Specialized for storing amino acids.
Essential and Non-Essential Amino Acids
- Plants and microorganisms can synthesize all 20 standard amino acids.
- Mammals cannot synthesize all 20 and must obtain some from their diet.
- Essential amino acids: Must be supplied in the diet.
- Non-essential amino acids: Can be synthesized by the organism.
- Human essential amino acids: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine.
- Human non-essential amino acids: Alanine, Arginine, Asparagine, Aspartic acid, Cysteine, Glutamine, Glutamic acid, Glycine, Proline, Serine, Tyrosine.
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Description
Dive into the fascinating world of amino acids with this quiz. Learn about their basic structure, classifications, and examples of both polar and non-polar types. Test your knowledge on their properties and functions in biology.
