Introduction to Biochemistry
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Introduction to Biochemistry

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@AdmirableMaracas

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Questions and Answers

What is the equilibrium constant, Keq, defined as?

Keq = [H+][OH-]/[H2O]

What is the equilibrium constant, Keq, of water under standard conditions?

  • 1.8x10^-16 M (correct)
  • 1x10^-7 M
  • 5x10^-5 M
  • 1x10^-14 M

    • In pure water, the concentration of protons ([H+]) is equal to the concentration of hydroxide ions ([OH-]).

    True

    What is the pH of a solution with a [H+] concentration of 10^-2 M?

    <p>pH = 2</p> Signup and view all the answers

    What is the pH of a solution with a [OH-] concentration of 10^-2 M?

    <p>pH = 12</p> Signup and view all the answers

    What is biochemistry?

    <p>Biochemistry is the study of the molecules and biochemical reactions of life.</p> Signup and view all the answers

    Which six non-metallic elements constitute more than 97% of the weight of living organisms?

    <p>C, O, H, N, S, P</p> Signup and view all the answers

    Water is the most indispensable nutrient for humans.

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

    Macromolecules are polymers created by joining smaller organic molecules, referred to as ________, via condensation reactions.

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

    What is the main characteristic underlying the properties of water?

    <p>Water is a polar molecule.</p> Signup and view all the answers

    What is the angle between the two covalent O-H bonds in water?

    <p>104.5 degrees</p> Signup and view all the answers

    What type of bond is formed between the slightly positive hydrogen atom of one molecule and the slightly negative oxygen atom of another molecule?

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

    What is the heat energy required to disrupt a hydrogen bond in water?

    <p>Approximately 20 kJ/mole</p> Signup and view all the answers

    Which type of molecules are hydrophobic and do not dissolve in water?

    <p>Non-polar molecules</p> Signup and view all the answers

    Water is the only molecule capable of establishing hydrogen bonds.

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

    Study Notes

    Introduction to Biochemistry

    • Biochemistry is the study of the molecules and biochemical reactions of life.
    • It explores the molecular mechanisms that underlie the functioning of living organisms.

    Importance of Water

    • Water is the most indispensable nutrient, and humans can survive only a few days without it.
    • Life is a water-based phenomenon, and water constitutes 60-70% of the mass of cells.
    • Water is an excellent solvent, and macromolecules are subdivided according to their water affinity (hydrophilic versus hydrophobic).

    Functions of Water

    • Transports nutrients and oxygen
    • Regulates cell structure
    • Aids in regulating the body temperature
    • Serves as a shock absorbent
    • Serves as a solvent
    • Cleanses the blood of waste

    Structure of Water

    • Water is a polar molecule, with a V-shaped structure and a 104.5o angle between the two covalent O-H bonds.
    • Oxygen has 8 electrons, 2 in the inner shell and 6 in the outer shell, which can accommodate 8 electrons in one s and three p orbitals.
    • The outer shell electrons occupy 4 sp3 hybrid orbitals, which are pictured as occupying the four corners of a tetrahedron.

    Hydrogen Bonding

    • Hydrogen bonds are a type of non-covalent attraction between the slightly positive hydrogen atom of one molecule and the slightly negative oxygen atom of another molecule.
    • The water molecule contributing the hydrogen is called the hydrogen donor, and the molecule contributing the electronegative atom is called the hydrogen acceptor.
    • Hydrogen bonds are weaker than covalent bonds, but are crucial for the structure and function of macromolecules.

    Properties of Water

    • High melting point of ice due to hydrogen bonding
    • Lower density of solid phase compared to liquid phase
    • High specific heat/heat capacity
    • High heat of vaporization

    Non-covalent Interactions

    • Hydrogen bonds: between hydrogen donor and hydrogen acceptor
    • Charge-charge interactions: electrostatic interactions between two charged molecules
    • Van der Waals forces: weak non-covalent interactions between permanent dipoles of two uncharged polarized bonds
    • Hydrophobic interactions: the exclusion of non-polar molecules from water, leading to their association with each other

    Ionization of Water

    • Water can ionize into hydronium (H3O+) and hydroxide (OH-) ions
    • The ionization of water is a reversible reaction, and the concentrations of reactants and products reach equilibrium
    • The ion product for water (Kw) is 1x10-14 M2

    pH and pOH

    • pH is a logarithmic scale that measures the concentration of protons in a solution
    • pH = -log[H+] = log 1/[H+]
    • pOH is a logarithmic scale that measures the concentration of hydroxide ions in a solution
    • pOH = -log[OH-] = log 1/[OH-]

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    Description

    This quiz covers the basics of biochemistry, including the definition and importance of biochemistry, the composition of living organisms, and the functions of water in biological systems.

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