Biochemistry by dffhrtcv3

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									Biochemistry
Central Texas College
BIOL 2402
Chelsea Loafman, MS
Solutions
   Solutions are a                     See figure 2-14 in
    combination of:
                                         text.
    ◦ Solute: substances
      dissolved in a liquid
    ◦ Solvent: the liquid in which
      the solute dissolves
       Water is the universal
        solvent
   Solubility: how easily it
    dissolves
    ◦ Hydrophilic- “water loving”
    ◦ Hydrophobic- “water
      fearing”
Solution Concentration
   Solute per solution
   The amount of solute is expressed in mass
    (g or mg) or number of molecules (mol)
    ◦ Mole: 6.02x1023 particles
   Molarity
    ◦ Number of moles of a solute in a liter of solution
      (mol/L or M)
   Equivalents are used to express the
    concentration of ions
    ◦ One equivalent (eq) is the molarity of an ion
      times the number of charges the ion has
Molecular Mass
   In order to determine the mass of a single
    molecule:
    ◦ Find the atomic mass for each element present
    ◦ Multiply each by how many atoms of the element
      there are in the whole molecule
    ◦ Add the totals for each element together to give
      the mass of the whole molecule
   The mass of 1 mole of a substance is
    affected by the molecular mass of that
    substance
  Molecular Mass-Glucose
 (# of atoms) x (atomic mass of the element) = Molecular mass of molecule



Element        # of atoms     Atomic mass of element        Molecular mass
Carbon (C)     6              12.0 amu                      72.0 amu
Hydrogen (H)   12             1.0 amu                       12.0 amu
Oxygen (O)     6              16.0 amu                      96.0 amu
                                                 Sum Total 180.0 amu
Creating Solutions
 Percent solution allows for a solution to
  be prepared based on weight/volume
  rather than particle number (mol)
 X parts solute per 100 parts solution
    ◦ 5% glucose solution: 5 grams glucose
      dissolved in water to make a final volume of
      100mL
    ◦ 0.1% HCl solution: 0.1mL acid dissolved in
      water to make a final volume of 100mL
pH-The Power of Hydrogen
 pH is a scale used to show the
  concentration of H+ ions or the acidity of
  a substance
 The pH scale runs from 0-14 with each
  whole number change representing a 10x
  change in H+ ion concentration
 The concentration of H+ is inversely
  related to the concentration of OH-
pH Scale
    Acidic

    ◦ 0-6.999
                                       See figure 2-15 in
    ◦ The lower the number the          text.
      more acidic the substance
      and the higher the H+
      concentration
   Neutral-pure water
    ◦ 7
    ◦ Equal concentration of H+
      and OH- (H2O)
   Basic/Alkaline
    ◦ 7.0001-14
    ◦ The higher the number the
      more basic/alkaline the
      substance and the lower the
      OH- concentration
pH Homeostasis
 Normal body pH is 7.40 and is regulated in a narrow range
 Alkalosis: pH of 7.5-7.8
    ▫ Feelings of being agitated or dizzy
    ▫ Causes include hyperventilation, mild vomiting
   Acidosis: pH of 7.0-7.3
    ▫ Feelings of being disoriented or fatigued
    ▫ Causes include impaired breathing, severe vomiting
   In order to maintain homeostasis we must combat changes
    in the body’s pH
    ◦ Buffers combat increasing acidity by having a strong affinity for
      H+ and therefore taking them “out of play” and stabilizing pH
    ◦ Bicarbonate anion is a key buffer in the body
    ◦ Examples:
     CO2 + H2O            H2CO3         HCO3- + H+

     (H+ + Cl-) + (HCO3- + Na+)           (H2CO3) + (Cl- + Na+)
     Hydrochloric     Sodium               Carbonic   Sodium Chloride
         acid       Bicarbonate              Acid       (table salt)
Proteins
   Considered the body’s “work horses”
   Can be insoluble that provide structural
    support or soluble that provide one of the
    following functions:
    ◦ Enzymes
    ◦ Membrane transporters
    ◦ Signal molecules
    ◦ Receptors
    ◦ Binding proteins
    ◦ Regulatory proteins
    ◦ Immunoglobulin
    *all contain a binding site
Proteins
    Ligand: a molecule that binds

    to another                             See figure 2-16 in
    ◦ Substrate: ligands that bind to
      enzymes or membrane
                                            text.
      transporters
   The ligand must be
    compatible with the binding
    site of the protein
    ◦ Binding occurs through
      hydrogen bonding, ionic
      bonding, or van der Waals
      forces
   The binding site changes
    shape slightly to fit snugly
    with the ligand
   Proteins are specific about
    what ligands they will bind to
Protein Affinity
 Proteins have certain attractions to specific
  ligands called an affinity that will increase the
  potential for binding
 Binding of a protein and ligand can be reversible
  as they go through a dissociation process
    ◦ P+L       PL      P+L
    ◦ Equilibrium is reached when binding rate matches
      dissociation rate
 Some ligands become competitors as they fight
  for the ability to bind with a protein
 Agonists mimic another ligands action by binding
  to the receptor site on a protein
    ◦ Ex: nicotine mimics acetylcholine
Protein Binding
   Affinity can change in         See figure 2-17 &
    different situations to
    alter the binding ability       2-18 in text.
    of the protein
   Isoforms mimic other
    proteins functionally but
    carry and affinity for
    different ligands
    ◦ Ex-fetal and adult
      hemoglobin
   Some proteins need to
    be activated before they
    can bind to ligands
    ◦ Cofactors
Modulation of Protein Binding
   Modulators affect protein
    binding or activity                          See figure 2-19 &
   Chemical modulators                           2-20 in text.
    ◦ Antagonists/inhibitors
       Competitive inhibitors fight with
        normal ligands for the binding site
        (reversible binding)
       Irreversible inhibitors prevent
        normal ligand binding permanently
    ◦ Agonist or antagonist
       Allosteric modulators bind to a
        regulatory site that changes the
        binding site (reversible)
       Covalent modulators bind
        covalently to proteins to alter one
        of the properties of the protein
   Physical modulators include
    pH and temperature
    ◦ Proteins become denatured an
      lose their confirmation
Physical Modulation
   See figure 2-21 in text.
Protein Binding Overview
   See table 2-3 in text.
Protein Numbers
 Up-regulation: programmed production of
  proteins to change a cell response
 Down-regulation: programmed removal of
  proteins to change a cell response
 A saturation point can be reached where
  the response peaks since all of the
  proteins are saturated with ligands
  despite a rising number of ligands
Up vs Down Regulation
   See figure 2-22 in text.
Saturation
   See figure 2-23 in text.
Example
   Which has a higher affinity for oxygen?



   See figure 2-24 in text.

								
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