Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
© 2009 Ebneshahidi
Dr. Ali Ebneshahidi
A . Introduction
Chemistry – science that deals with the composition ofsubstances and the changes that take place in theircomposition.
Organic chemistry – chemistry that deals with organicsubstances (those that contain carbon and hydrogen).
© 2009 Ebneshahidi
substances (those that contain carbon and hydrogen).
Biochemistry - chemistry of living organisms; essentialfor understanding physiology because body functionsinvolve chemical changes that occur within cells.
Matter – anything that has weight (or mass) and takes
up space. It can be solids, liquids, or gases.
Energy
Energy – the ability to do work . Potential energy(PE) is stored energy in matters ; Kinetic energy(KE) is working energy produced by the motion ofmatters.
© 2009 Ebneshahidi
Energy occurs in 4 forms in the human body:chemical, electrical, radiant, and mechanical energy.Chemical energy is the most important form interms of actually driving chemical reactions.
Models of the Atom
© 2009 Ebneshahidi
Atomicnumber (AN)= number ofprotons =number ofelectrons.
© 2009 Ebneshahidi
electrons.
Atomic weight(AW) = numberof protons +number ofneutrons.
IONS
In addition to neutrons, the electrons ofatoms tend to change also – atoms that haveeither lost or gained electrons are calledions. Atoms that have lost electrons (as aresult, now contain more p+ than e-) are
© 2009 Ebneshahidi
result, now contain more p than e ) arecalled cations which carry positive charges,while atoms that have gained excessiveelectrons (as a result, now contain more e-
than p+) are called anions which carrynegative charges.
Chemically Reactive Elements
Reactive elementsdo not have their
© 2009 Ebneshahidi
do not have theiroutermost energylevel fully occupiedby electrons.
Bonding of atoms
Ionic bonding = formed by attraction ofopposite charges of a cation and an anion.
(e.g. Na+ + Cl- →NaCl)
© 2009 Ebneshahidi
Formation of an Ionic Bond
© 2009 Ebneshahidi
Covalent bond
formed by sharing of electrons between twoatoms (e.g. Cl + Cl →Cl2). The strongest typeof bonding.
© 2009 Ebneshahidi
formed by weak attraction between H+ and nitrogen (N) or oxygen(O) [e.g. H of a water molecule attracting to O of another watermolecule]. The weakest type of bonding.
Hydrogen Bond
© 2009 Ebneshahidi
Four Types of Chemical Reactions
Chemical reactions involve the formation, breaking, orrearrangement of chemical bonds. There are 4 general types:
Dehydration synthesis: A + B → AB + water
Decomposition (or hydrolysis): AB + water → A + B
© 2009 Ebneshahidi
Decomposition (or hydrolysis): AB + water → A + B
Exchange: AB + CD → AD + CB
Reversible: A + B < - - - > AB
The rate of Chemical Reactions
size of reacting molecules: smaller molecules have greaterkinetic energy which produces faster reaction rate.
Temperature: higher temperature creates greater kineticenergy and faster reaction rate.
© 2009 Ebneshahidi
Concentration of reactants: higher concentration producesfaster rate .
Presence of catalysts: inorganic catalysts or organiccatalysts (enzymes) increase reaction rate.
Electrolytes = compounds that release ions whendissolved in water (e.g. NaCl + water → Na+ + Cl- ).
Acids = electrolytes that release H+ (e.g. H2 CO3 → H+ +HCO3
- ).
© 2009 Ebneshahidi
Bases = electrolytes that release anions that can combinewith H+ (e.g. NaOH → Na+ + OH- ).
Salts = substances formed by the reaction between anacid and a base (e.g. HCl + NaOH → H2O + NaCl ).
PH
measurement of H+ concentration in a solution
- More H+ = lower PH = more acidic
- Less H+ = higher pH = less acidic
© 2009 Ebneshahidi
-Ph scale is form 0 to 14, where themidpoint (pH 7.0) is neutral. From pH 0to 6.9, it is acid; while from pH 7.1 to 14is base.
PH Scale
© 2009 Ebneshahidi
Organic substances = chemicals that contain C andH (e.g. Carbohydrates, Protein, Fat, and nucleicacid).
Inorganic substances = chemicals that do notcontain C and H (e.g. table salt or NaCl, carbon
© 2009 Ebneshahidi
contain C and H (e.g. table salt or NaCl, carbondioxides or CO2 , ammonia or NH3).
(Most inorganic substances are small, electrolytesand usually use ionic bonding, while most organicsubstances are large, non electrolytes, and usuallyuse covalent bonding ).
An Organic Compound(cholestrol)
© 2009 Ebneshahidi
Protein
© 2009 Ebneshahidi
Figure 2.3
Carbohydrate
© 2009 Ebneshahidi
Nucleic Acid
© 2009 Ebneshahidi
When a substance is dissolved in a liquid (ex. water), asolution is formed. The substance that is dissolved is the soluteand the liquid in which the dissolution occurred is the solvent.
Concentration: The measure of dissolution of a particularsolute in a given volume of solvent. it is measured in molarity.
Solution and concentration
© 2009 Ebneshahidi
solute in a given volume of solvent. it is measured in molarity.
Molarity: The number of solute molecule per unit volume ofsolution.
Buffer: A substance that can react with an acid or a base andthus resist a change in PH.
Tonicity
the ability of a solution to change the tone or shape ofcells by changing their internal H2O volume.
- Hypertonic: solutions with higher osmotic pressure -cells in a Hypertonic solution lose H2O and shrink.
© 2009 Ebneshahidi
- Hypotonic : solution with a lower osmotic pressure -cells in hyportonic solution gain H2O and swell.
- Isotonic : same tonicity - cell in isotonic solutionsneither gain, nor lose H2O.
The effect of solutions of varying tonicities onred blood cell
© 2009 Ebneshahidi
1. Are always made of globular proteins.2. Can promote the rate of chemical reactions by billions of times.3. Can lower the activation energy – energy necessary to start areaction – resulting in a conservation of energy.
Enzymes
© 2009 Ebneshahidi
4. Are usually reusable or recycled.
5. Are always very specific – using its active site, eachenzyme is designed to bind to only one specific substance, thesubstrate and rapidly transforms the substrate into aproduct.
© 2009 Ebneshahidi
6. Many enzymes would not achieve their optimum efficiencyunless they are bound to a cofactor (i.e. ions, metals) or to acoenzyme (organic cofactors such as vitamins).
7. Most enzymes' names end with "ase“ (ex. DNAse,Sucrase).
Enzyme-substrate
complex (E–S)
1
Active site
Enzyme (E) Substrates (s)
Amino acids
H20
Mechanism of Enzyme Action
© 2009 Ebneshahidi
2
3
Internal rearrangementsleading to catalysis
Free enzyme (E)
Peptide bond
Dipeptide product (P)
Many factors affect enzyme activity:
Since all enzymes are made of globular proteins,and proteins are made of amino acids linked bypeptide bonds, enzymes can be affected ordenatured very easily.
© 2009 Ebneshahidi
denatured very easily.
Factors that could affect or denature enzymesinclude heat, radiation , electricity, certain chemicalsubstances, and extreme PH.
Synthesis and Hydrolysis of Sucrose :
Anabolic metabolism uses dehydration synthesis reaction to buildlarge molecules from small molecules.
Each reaction releases a water molecule and requires energy inputExample – monosaccharide + energy → polysaccharide + wateramino acids + energy → protein + water.
Metabolism
© 2009 Ebneshahidi
Catabolic metabolism
Uses hydrolysis (or decomposition) reaction to breakup large molecules into smaller molecules.
Each reaction requires a water molecule and releases
© 2009 Ebneshahidi
Each reaction requires a water molecule and releasesenergy.
Example -- triglyceride + water → fatty acids +energy.
Adenosine Triphosphate (ATP)
High- energy molecule that is derived from the nucleotide, adenine.
Contains 3 phosphate groups (PO4) and high-energy chemical bondsthat each time the bonds are broken, a large amount of energy isgenerated.
Energy is released by ATP is broken down by hydrolysis reaction:
© 2009 Ebneshahidi
Energy is released by ATP is broken down by hydrolysis reaction:ATP + water → ADP + PO4+ energy [ADP = adenosine diphosphate]
ADP + water → AMP + PO4 + energy
[AMP = adenosine monophosphate]
ATP
© 2009 Ebneshahidi