Podcast
Questions and Answers
What are the two main types of amino acids?
What are the two main types of amino acids?
- Essential and Non-Essential
- Aromatic and Non-Aromatic
- Charged and Uncharged
- Non-polar and Polar (correct)
All amino acids are chiral.
All amino acids are chiral.
False (B)
What is the name of the bond that links amino acids together?
What is the name of the bond that links amino acids together?
- Peptide bond (correct)
- Ionic bond
- Disulfide bond
- Hydrogen bond
What does the 'R' group refer to in the general structure of an amino acid?
What does the 'R' group refer to in the general structure of an amino acid?
Which of the following amino acids is commonly found in B-sheets?
Which of the following amino acids is commonly found in B-sheets?
What is the primary structure of a protein?
What is the primary structure of a protein?
Which of the following is NOT a force that stabilizes protein structure?
Which of the following is NOT a force that stabilizes protein structure?
What is the name of the structure formed when two or more polypeptides assemble together?
What is the name of the structure formed when two or more polypeptides assemble together?
What is the main difference between fibrous proteins and globular proteins?
What is the main difference between fibrous proteins and globular proteins?
Collagen is a globular protein.
Collagen is a globular protein.
What is the function of myoglobin?
What is the function of myoglobin?
What is the name of the protein that transports oxygen in red blood cells?
What is the name of the protein that transports oxygen in red blood cells?
What is the difference between the T-state and the R-state of hemoglobin?
What is the difference between the T-state and the R-state of hemoglobin?
What type of amino acid residues are commonly found in the interior of fibrous proteins?
What type of amino acid residues are commonly found in the interior of fibrous proteins?
Flashcards
Amino Acid Configuration
Amino Acid Configuration
The spatial arrangement of atoms in an amino acid, creating a chiral molecule.
R-group effect on amino acid
R-group effect on amino acid
The 'R' group determines the properties of an amino acid (charge, size, polarity).
Non-polar aliphatic amino acids
Non-polar aliphatic amino acids
Amino acids with nonpolar, hydrocarbon-based R groups.
Aromatic amino acids
Aromatic amino acids
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Polar uncharged amino acids
Polar uncharged amino acids
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Positively charged amino acids
Positively charged amino acids
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Negatively charged amino acids
Negatively charged amino acids
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Uncommon amino acids
Uncommon amino acids
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Amino acid zwitterion
Amino acid zwitterion
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Amphoteric nature of amino acid
Amphoteric nature of amino acid
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Titration curve of amino acid
Titration curve of amino acid
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pKa values of amino acids
pKa values of amino acids
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Peptide bond formation
Peptide bond formation
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N-terminus and C-terminus
N-terminus and C-terminus
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Disulfide linkages
Disulfide linkages
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Hydrogen bonding (in proteins)
Hydrogen bonding (in proteins)
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Van der Waals interactions
Van der Waals interactions
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Ionic interactions/Salt bridges
Ionic interactions/Salt bridges
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Hydrophobic interactions
Hydrophobic interactions
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Protein primary structure
Protein primary structure
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Protein secondary structure
Protein secondary structure
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Alpha-helix
Alpha-helix
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Study Notes
Amino Acids and Proteins
- Amino acids are the building blocks of proteins.
- The "R" group of an amino acid determines its properties (charge, size, polarity).
- Chiral molecules cannot be superimposed on their mirror images. Achiral molecules can.
- Amino acids exist in L or D forms. L-amino acids are commonly found in proteins.
- Amino acids are classified based on their R-groups into:
- Nonpolar aliphatic (e.g., Glycine, Alanine, Valine, Leucine)
- Aromatic (e.g., Phenylalanine, Tyrosine, Tryptophan)
- Polar uncharged (e.g., Serine, Threonine, Cysteine, Asparagine, Glutamine)
- Positively charged (e.g., Lysine, Arginine, Histidine)
- Negatively charged (e.g., Aspartate, Glutamate)
- Uncommon amino acids include 4-hydroxyproline, 5-hydroxylysine, 6-N-methyllysine, γ-Carboxyglutamate, Selenocysteine, and Pyrolysine. Ornithine and Citrulline are intermediates in amino acid biosynthesis.
- Amino acids are amphoteric, existing as dipolar ions (zwitterions) in water.
- The zwitterion form of an amino acid can act as either an acid or a base.
- Titration curves of amino acids help determine pKa values and the isoelectric point (pI).
- pKa values for different amino acids are provided on page 14.
- Amino acids join through peptide bonds to form peptides and proteins.
- Peptides and proteins have N-terminal and C-terminal ends.
- Forces that stabilize protein structure include disulfide linkages, hydrogen bonds, ionic interactions (salt bridges), van der Waals interactions, and hydrophobic interactions.
- Disulfide bonds are formed between cysteine residues.
- Hydrogen bonds are directional and stronger when acceptor atoms are at a 180° angle to H-bonded atoms.
- Van der Waals forces are transient, weak interactions between uncharged atoms.
- Ionic interactions occur between oppositely charged groups (e.g., carboxyl and amino groups).
- Hydrophobic interactions occur between nonpolar amino acid residues, typically in the protein core.
- Hydropathy index values are provided on page 25.
- Proteins have four levels of structure: primary, secondary, tertiary, and quaternary.
- Primary structure refers to the linear sequence of amino acids.
- Secondary structure includes alpha helices and beta sheets.
- Tertiary structure describes the overall three-dimensional folding of a polypeptide chain.
- Quaternary structure describes the arrangement of multiple polypeptide chains to form a functional protein.
- Fibrous proteins (e.g., keratin, collagen) have long strands or sheets. These structures are generally insoluble in water and often contain repetitive secondary structures.
- Globular proteins (e.g., myoglobin, hemoglobin) have folded structures, are usually soluble in water and often carry out specific functions.
- Myoglobin is a single polypeptide chain with a heme group that binds oxygen in muscle cells.
- Hemoglobin is a tetrameric protein found in red blood cells, responsible for oxygen transport, with two alpha and two beta polypeptide chains. It exhibits cooperative binding and has T and R states which allows it to bind oxygen efficiently.
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Description
Explore the basics of amino acids and their significance in protein structure. This quiz covers the classification of amino acids, their properties, and the concept of chirality. Additionally, learn about uncommon amino acids and their roles in biosynthesis.
