Metals in Biology
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Questions and Answers

What role does Mg2+ play in biological systems?

  • It is a component of vitamin B12.
  • It is primarily involved in oxygen transport.
  • It functions as a signaling molecule in muscle contraction.
  • It aids in phosphoester cleavage in nucleotide-utilizing enzymes. (correct)
  • Which trace metal is critical for the synthesis of methionine?

  • Ni
  • Co (correct)
  • Fe
  • Cu
  • What is the primary function of Mn in biological systems?

  • Nucleotide utilization.
  • Oxygen transport.
  • Electrostatic signaling.
  • Water splitting enzyme. (correct)
  • Which trace metal is known to be involved in electron transfer and oxygen activation?

    <p>Fe</p> Signup and view all the answers

    What key function does Ca2+ serve in cellular processes?

    <p>Receptor signaling and muscle contraction.</p> Signup and view all the answers

    Which metal is crucial for hydrogenase activity?

    <p>Ni</p> Signup and view all the answers

    Which trace metal is associated with the function of electron transfer proteins and oxygenases?

    <p>Fe</p> Signup and view all the answers

    What is the function of Cu in biological processes?

    <p>Oxygen transport and catalytic roles.</p> Signup and view all the answers

    What characteristic must a molecule possess to act as a ligand?

    <p>It must have an atom with a lone pair.</p> Signup and view all the answers

    Which of the following amino acid side chains can act as ligands to metals?

    <p>Histidine</p> Signup and view all the answers

    What role do Na+ and K+ ions play in cellular functions?

    <p>They maintain chemical gradients across cell membranes.</p> Signup and view all the answers

    Which of the following metals is always in the 2+ oxidation state?

    <p>Zinc</p> Signup and view all the answers

    What is a consequence of the Na/K pump's activity?

    <p>Coupling Na+ migration with ATP hydrolysis.</p> Signup and view all the answers

    Which of the following represents a bulk metal commonly found in biological systems?

    <p>Sodium</p> Signup and view all the answers

    What charge do bulk metals typically have?

    <p>1+ or 2+</p> Signup and view all the answers

    How does Na+ re-entry into the cell occur?

    <p>Coupled to sugar transport.</p> Signup and view all the answers

    What characterizes the binding curve of haemoglobin?

    <p>Sigmoidal</p> Signup and view all the answers

    What is the role of histidine (His) in the haemoglobin structure?

    <p>It acts as a ligand to attach haem and iron.</p> Signup and view all the answers

    How does haemoglobin's binding of oxygen influence its conformation?

    <p>It promotes a change from T-state to R-state.</p> Signup and view all the answers

    What effect does cooperativity have on haemoglobin's function?

    <p>It enhances the uptake and release of oxygen.</p> Signup and view all the answers

    What happens to the haemoglobin tetramer when one subunit undergoes a conformational change?

    <p>All subunits are induced to change.</p> Signup and view all the answers

    What is the primary function of myoglobin compared to haemoglobin?

    <p>To store oxygen rather than transport it.</p> Signup and view all the answers

    What is the primary ion involved in the reversible binding of O2 in haemoglobin?

    <p>Fe(II)</p> Signup and view all the answers

    In which state does haemoglobin have a stronger affinity for oxygen?

    <p>R-state</p> Signup and view all the answers

    What role does carbonic anhydrase play in the red blood cells?

    <p>It catalyzes the conversion of CO2 to carbonic acid.</p> Signup and view all the answers

    How does carbonic acid affect the pH in red blood cells?

    <p>It decreases the pH, causing hemoglobin to release oxygen.</p> Signup and view all the answers

    What is the significance of the Zn2+ in carbonic anhydrase?

    <p>It serves as a co-factor that speeds up the deprotonation of water.</p> Signup and view all the answers

    What is the structure of hemoglobin?

    <p>A tetramer made up of four subunits.</p> Signup and view all the answers

    In what environment does carbonic anhydrase convert carbonic acid back to CO2?

    <p>In the lungs.</p> Signup and view all the answers

    What is the rate determining step for the reaction catalyzed by carbonic anhydrase?

    <p>Deprotonation of water to create a hydroxyl nucleophile.</p> Signup and view all the answers

    What is the effect of rising pH in the lungs on hemoglobin?

    <p>It strengthens hemoglobin's binding to oxygen.</p> Signup and view all the answers

    What is the rate at which the deprotonation step occurs in absence of the enzyme?

    <p>$0.01 s^{-1}$</p> Signup and view all the answers

    What drives ATP synthesis in mitochondria?

    <p>Proton translocation</p> Signup and view all the answers

    Which complex does NOT participate in the electron transport chain within mitochondria?

    <p>Complex V</p> Signup and view all the answers

    Which ion is crucial for the function of the heme group in cytochrome c?

    <p>Iron</p> Signup and view all the answers

    What change occurs in the iron (Fe) of heme when it binds to O2?

    <p>The Fe becomes smaller and is pulled into the heme plane.</p> Signup and view all the answers

    In which state does the hemoglobin tetramer exhibit low O2 affinity?

    <p>T-state</p> Signup and view all the answers

    In the electron transport chain, where do electrons originate?

    <p>NADH</p> Signup and view all the answers

    What initiates the cooperativity in O2 binding in hemoglobin?

    <p>The movement of His and the protein conformation change.</p> Signup and view all the answers

    What does the term 'respirasome' refer to?

    <p>Structure of respiration machinery</p> Signup and view all the answers

    What is the primary focus of bioenergetics?

    <p>The study of energy storage and release in biological systems.</p> Signup and view all the answers

    What is the role of ATP synthase?

    <p>ATP production</p> Signup and view all the answers

    Which two processes form a large energy cycle in biology?

    <p>Photosynthesis and respiration.</p> Signup and view all the answers

    Which proton gradient potential is cited in the respiration process?

    <p>-320 mV to +800 mV</p> Signup and view all the answers

    What role do His and Met residues play in cytochrome c?

    <p>Iron binding</p> Signup and view all the answers

    What role do metal ions play in bioenergetics?

    <p>They facilitate electron transfer and have different redox states.</p> Signup and view all the answers

    What happens when one molecule of O2 binds to hemoglobin?

    <p>It facilitates the binding of additional O2 molecules.</p> Signup and view all the answers

    Which of the following is NOT a product of respiration?

    <p>C6H12O6</p> Signup and view all the answers

    Study Notes

    Metals in Biology

    • Bulk Metals: Sodium (Na), Potassium (K), Magnesium (Mg), and Calcium (Ca) are essential for life, often as cations. Trace metals include Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), and Molybdenum (Mo).

    • Metal Ions in Biological Processes: Many biological processes rely on metal ions. For example, bulk metals Na+ and K+ are crucial for maintaining ionic strength within cells. They are pumped in/out of cells coupled to ATP.

    • Metal Roles in Enzymes and Proteins: Many enzymes use metal ions for catalysis and structural support. Examples include Mg2+ in enzymes where it assists with nucleotide use in phosphoester cleavage. Ca2+ plays a major role in cell signaling like in voltage-gated calcium channels during muscle action. Metal ions like Ni are part of hydrogenases. Co is part of vitamin B12 in methionine synthesis and Zn is common in various enzymes and zinc fingers.

    • Redox Reactions: Electron transfer reactions are often facilitated by metals with variable oxidation states, like Fe and Cu, in electron transfer proteins and oxidases. These elements are often abundant in biological systems, particularly iron in mammals.

    • Metal Centers and Their Function: Metal clusters (like iron-sulfur clusters) found in proteins are involved in electron transfer and other redox processes. For example, Mo is found within the cofactor of enzymes involved in nitrogen fixation. A manganese cluster catalyzes O2 evolution in plants' water splitting enzymes.

    • Oxygen Transport: Haemoglobin, a protein in red blood cells, uses an iron ion to bind and transport oxygen. This occurs cooperatively, as the binding of one oxygen molecule to hemoglobin leads to increased affinity for binding subsequent oxygen molecules.

    • Respiration: Protons are pumped across the inner membrane of mitochondria during electron transport chain events. This drives ATP synthesis.

    • Photosynthesis: Some metal ions, such as copper in plastocyanin, are important components in photosynthesis, where they facilitate electron transport between different protein complexes.

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    Description

    Explore the essential roles of bulk and trace metals in biological systems through this quiz. Learn how metal ions contribute to cellular functions, enzyme activity, and redox reactions. Test your knowledge on the importance of these metals in life processes.

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