Introduction to Biochemistry
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Questions and Answers

What type of interaction occurs between (+) and (-) molecules?

  • Covalent bonds
  • Electrostatic interactions (correct)
  • Hydrogen bonds
  • Hydrophobic interactions
  • What is the primary reason that water is considered the universal solvent?

  • It has a low heat capacity.
  • It interacts with ionic and polar compounds. (correct)
  • It has strong covalent bonds.
  • It can dissolve only non-polar substances.
  • How many hydrogen bonds are typically formed by a water molecule?

  • 4
  • 1.5
  • 2.3 (correct)
  • 3
  • Which of the following best describes a buffer system?

    <p>A solution of weak acid and its conjugate base.</p> Signup and view all the answers

    What characteristic of water contributes to its high boiling and melting points?

    <p>Hydrogen bonding</p> Signup and view all the answers

    What is the purpose of the Henderson-Hasselbalch equation?

    <p>To determine aspects of a given buffer system.</p> Signup and view all the answers

    Which phenomenon is associated with the tendency of hydrophobic molecules to coalesce in water?

    <p>Hydrophobic interactions</p> Signup and view all the answers

    Which factor does NOT influence buffer capacity?

    <p>Temperature of the solution</p> Signup and view all the answers

    Which biomolecule serves as the central atom in most biomolecules due to its bonding abilities?

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

    What is the primary characteristic of hydrocarbons?

    <p>They are relatively inert and non-polar.</p> Signup and view all the answers

    Which functional group is involved when one hydrogen in methane is replaced with a hydroxyl group?

    <p>Hydroxyl group</p> Signup and view all the answers

    What type of reaction requires energy to synthesize larger molecules from smaller ones?

    <p>Anabolic pathways</p> Signup and view all the answers

    Which of the following is considered a major property of water molecules?

    <p>Water forms hydrogen bonds.</p> Signup and view all the answers

    What type of biochemical reaction involves the substitution of a nucleophile?

    <p>Nucleophilic substitution</p> Signup and view all the answers

    Which molecules are fundamental pathways found in many organisms?

    <p>Carbohydrates, lipids, proteins, and nucleic acids</p> Signup and view all the answers

    Which reaction type involves breaking down larger molecules into smaller ones and releases energy?

    <p>Catabolic pathways</p> Signup and view all the answers

    What is the primary function of bicarbonate in blood pH regulation?

    <p>It acts as a buffer to maintain blood pH.</p> Signup and view all the answers

    What pH level defines acidosis?

    <p>pH &lt; 7.35</p> Signup and view all the answers

    Which mechanism do kidneys primarily use to control blood pH?

    <p>Excreting protons via ammonia or phosphate.</p> Signup and view all the answers

    What occurs during respiratory acidosis?

    <p>Increased CO2 and decreased pH.</p> Signup and view all the answers

    Which of the following pH levels indicates alkalosis?

    <p>pH &gt; 7.45</p> Signup and view all the answers

    What impact does hyperventilation have on blood CO2 levels?

    <p>Decreases CO2 levels.</p> Signup and view all the answers

    Which pKa value corresponds to the phosphate buffer system in intracellular fluid?

    <p>pKa = 7.2</p> Signup and view all the answers

    What happens to bicarbonate retention when CO2 levels increase in the blood?

    <p>Bicarbonate retention increases.</p> Signup and view all the answers

    Study Notes

    Introduction to Biochemistry

    • Biochemistry studies the molecular basis of life, focusing on the interactions between biomolecules.

    Principles of Living Organisms

    • Living organisms consist of highly organized cells, requiring a constant energy source for maintaining life.
    • Regulated chemical reactions are essential, and certain fundamental pathways are common across many species.
    • Key biomolecules include carbohydrates, lipids, proteins, and nucleic acids, which encode the necessary instructions for life.
    • Reproduction is a fundamental characteristic inherent to all organisms.

    Biomolecules

    • Water is the most critical molecule for life, serving as a solvent and participating in biochemical reactions.
    • Important elements in biomolecules include carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), and sulfur (S), with carbon being central due to its tetravalent nature.

    Hydrocarbons

    • Composed solely of carbon and hydrogen, hydrocarbons are non-polar and hydrophobic, serving as precursors for major biomolecules.
    • Examples include natural gas, fossil fuels, and coal.

    Functional Groups

    • Functional groups modify molecular properties; e.g., replacing a hydrogen atom in methane (CH₄) with a hydroxyl group (-OH) forms methanol (CH₃OH).

    Biochemical Reactions

    • Various types of biochemical reactions include:
      • Nucleophilic substitution
      • Hydrolysis
      • Elimination
      • Addition
      • Isomerization
      • RedOx reactions
      • Oxidation reactions

    Metabolic Pathways

    • Anabolic pathways build larger molecules from smaller ones and require energy input.
    • Catabolic pathways involve the breakdown of larger molecules into smaller components, releasing energy.

    Water and Hydrogen Bonding

    • Water molecules are polar and engage in hydrogen bonding, which plays a significant role in its unique properties.
    • Each water molecule forms approximately 2.3 hydrogen bonds, while ice can form up to 4 hydrogen bonds.

    Non-covalent Interactions

    • Ionic bonds occur between charged particles, while electrostatic interactions involve charged ions.
    • Hydration refers to the interaction of water with ions in solutions.

    Non-covalent Bonding

    • Key types include:
      • Hydrogen bonds (present in water, amines, alcohols, carboxylic acids)
      • Van der Waals forces due to uneven electron distribution
      • Hydrophobic interactions occurring in aqueous environments, promoting the coalescence of hydrophobic molecules.

    Properties of Water

    • Water remains liquid at normal temperatures and possesses high boiling and melting points.
    • It has elevated heats of fusion and vaporization and high heat capacity, resulting in significant surface tension.

    Acids and Bases

    • Acids function as proton donors, while bases act as proton acceptors.
    • Distinctions exist between strong and weak acids and bases, along with their conjugate forms.

    Buffers

    • Buffers consist of weak acids and their conjugate bases, stabilizing pH by absorbing excess acids or bases.
    • Their effectiveness is influenced by the molar concentration and the ratio of acid to base.

    Henderson-Hasselbalch Equation

    • Used to calculate key characteristics of buffer solutions and understand their pH dynamics.

    Biological Buffers

    • Bicarbonate serves as a biological buffer in blood, with a pKa of 6.37 and normal blood pH around 7.4.
    • Phosphate acts as an intracellular buffer with a pKa of 7.2, crucial for phosphorylation processes. Proteins, including hemoglobin, also function as buffers.

    Control of Blood pH

    • Blood pH regulation involves lung excretion of carbon dioxide and renal excretion of hydrogen ions via ammonia and phosphate pathways.
    • Most bicarbonate is reabsorbed during these processes.

    pH Conditions

    • Acidosis occurs when pH falls below 7.35.
    • Alkalosis arises when pH exceeds 7.45.

    Respiratory Acidosis

    • Results from decreased respiratory rate, increasing CO₂ and lowering blood pH.
    • Hyperventilation leads to decreased CO₂ levels, lower proton excretion by kidneys, and consequently a higher pH.

    Metabolic Acidosis

    • Characterized by a decrease in plasma bicarbonate, often due to increased metabolic acids.

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    Description

    This quiz covers the fundamental principles of biochemistry, focusing on the molecular basis of life. It delves into cellular organization, energy sources, and the essential chemical pathways that sustain living organisms. Key biomolecules such as carbohydrates, lipids, and proteins are also explored.

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