# Biochemistry by dffhrtcv3

VIEWS: 19 PAGES: 20

• pg 1
```									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
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
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.

```
To top