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Questions and Answers
What type of bond is formed between the amino group of one amino acid and the carboxyl group of an adjacent amino acid?
What type of bond is formed between the amino group of one amino acid and the carboxyl group of an adjacent amino acid?
Which of the following types of proteins are formed only of amino acids?
Which of the following types of proteins are formed only of amino acids?
Which of the following statements about hydrogen bonds is true?
Which of the following statements about hydrogen bonds is true?
What are glycoproteins?
What are glycoproteins?
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Which of the following statements about ionic bonds is correct?
Which of the following statements about ionic bonds is correct?
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What is the primary component that proteins are made of?
What is the primary component that proteins are made of?
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Which of the following elements is NOT commonly found in proteins?
Which of the following elements is NOT commonly found in proteins?
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What term is used to describe molecules containing fewer than 50 amino acids?
What term is used to describe molecules containing fewer than 50 amino acids?
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Which functional group is present in all amino acids?
Which functional group is present in all amino acids?
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What type of bond forms between amino acids during protein synthesis?
What type of bond forms between amino acids during protein synthesis?
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Which of the following proteins is responsible for transporting oxygen in blood?
Which of the following proteins is responsible for transporting oxygen in blood?
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What distinguishes amino acids from each other?
What distinguishes amino acids from each other?
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Which type of bond is considered weak and physical in proteins?
Which type of bond is considered weak and physical in proteins?
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How many amino acids must a molecule have to be classified as a protein?
How many amino acids must a molecule have to be classified as a protein?
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Which element is specifically mentioned as essential in certain specialized proteins?
Which element is specifically mentioned as essential in certain specialized proteins?
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Study Notes
Protein Structure and Function
- Proteins are organic nitrogenous compounds composed of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). Nitrogen makes up 16% of a protein's mass. Other elements like sulfur, phosphorus, and iron can also be found in certain specialized proteins. Examples include casein (milk protein) containing phosphorus and hemoglobin (an oxygen-transporting blood protein) requiring iron.
Amino Acids: The Building Blocks
- Proteins are long chains of amino acids.
- Amino acids are the monomers that form protein polymers.
Amino Acid Structure
- Central carbon atom (alpha-carbon)
- Amino group (-NH2)
- Carboxyl group (-COOH)
- Hydrogen atom (-H)
- Variable R-group (side chain): This group varies among different amino acids, determining their unique chemical properties.
Peptide Bonds
- Amino acids link together through peptide bonds.
- A peptide bond is formed between the carboxyl group of one amino acid and the amino group of another, releasing a water molecule (condensation reaction).
Polypeptides and Proteins
- Chains of amino acids connected by peptide bonds are called polypeptides.
- Proteins are polypeptides with more than 50 amino acids.
Levels of Protein Structure
- Primary: The linear sequence of amino acids.
- Secondary: Local folding patterns (alpha-helix, beta-sheet) stabilized by hydrogen bonds.
- Tertiary: The overall three-dimensional shape of a protein stabilized by various interactions (hydrogen bonds, ionic bonds, disulfide bridges, hydrophobic interactions).
- Quaternary: The arrangement of multiple polypeptide chains in a protein (e.g. hemoglobin).
Types of Bonds
- Covalent: Strong chemical bonds like peptide bonds that hold the amino acid sequence together. Not affected by denaturation.
- Non-covalent: Weak physical bonds like hydrogen bonds, ionic bonds that maintain the 3D structure and can be disrupted by changes in environment (denaturation).
Protein Classification
- Simple proteins: Hydrolyze to yield only amino acids (Ex: Albumin, Myosin, Collagen, Keratin, Elastin, Glutelins)
- Conjugated proteins: Composed of a protein part and a non-protein part (Ex: Glycoproteins [hormones, blood groups], Phosphoproteins [milk protein, egg yolk], Metalloproteins [insulin, ferritin/iron], Lipoproteins [LDL, HDL], Nucleoproteins [chromatin], Chromoproteins [chlorophyll])
- Derived proteins: Denatured or modified forms of simple or conjugated proteins (Ex: resulting from changes in pH, heat or certain chemicals).
Protein Denaturation
- Denaturation is the loss of a protein's three-dimensional structure.
- Denaturation causes loss of function.
- Causes include high temperature, high pressure radiation (X-rays, UV rays), strong acids/bases, organic solvents, and changes in pH.
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Description
Test your knowledge on the structure and function of proteins, including the role of amino acids and peptide bonds. This quiz covers the composition of proteins and the significance of various amino acids. Prepare to explore the molecular building blocks that are essential for life!
