lecture 2 natsci ii josephine b. guerrero, md asst. professor, department of biology
TRANSCRIPT
Chemistry of LifeLecture 2 NatSci II
Josephine B. Guerrero, MD
Asst. Professor, Department of Biology
Concepts: Matter – anything that has mass and
occupies space Atomic theory – all elements are composed
of atoms; each element with a unique number of electrons, protons and neutrons
Elements – simplest form that cannot be broken down further
Compounds – composed of two or more elements joined by a chemical bond
Chemical Bonds
1. Covalent bonds
2. Hydrogen bonds
3. Ionic bonds
4. Electrostatic bonds
Elements found in living systems
What is the difference between organic and inorganic molecules?
Inorganic Molecules – made up of elements except C
Organic Molecules – made up of C except CO and CO2
Acids, Bases and Buffers Acids – release H+; proton donors
Bases – release OH-; proton acceptors
Salt – product of neutralization process between an acid and a base
Buffers – substances that help resist changes in pH; mixture of a weak acid and its conjugate base or a weak base and its conjugate acid
[H+] pH Example
Acids
1 X 100 0 HCl
1 x 10-1 1 Stomach acid
1 x 10-2 2 Lemon juice
1 x 10-3 3 Vinegar
1 x 10-4 4 Soda
1 x 10-5 5 Rainwater
1 x 10-6 6 Milk
Neutral 1 x 10-7 7 Pure water
Bases
1 x 10-8 8 Egg whites
1 x 10-9 9 Baking soda
1 x 10-10 10 Tums® antacid
1 x 10-11 11 Ammonia
1 x 10-12 12Mineral lime - Ca(OH)2
1 x 10-13 13 Drano®
1 x 10-14 14 NaOH
CO2 + H2O [H2CO3] H+ + HCO3-
produced by metabolism
always available
in equilibrium
with species on either
side
produced by metabolism
pre-existing blood buffer
directly expelled in
lung
adjusted in kidney via physiologic mechanisms unrelated
to pH
converted to products on
left by carbonic
anhydrase (RBC)
adjusted in kidney or
reacts with bicarbonate to
make products on
left
adjusted in kidney or
reacts with H+ to make products on
left
Biomolecules:
Carbohydrate
Lipids
Proteins
Nucleotides
Carbohydrates
Simple sugars or monosaccharides forming long chains of polysaccharides
Ranges from a 4C, 5C or 6C monosaccharide
Useful as an energy source: glucose
Lipids
Also known as fatty acids; composed of a glycerol molecule with three fatty acid chains
Saturated vs. unsaturated fatty acid
Useful as a energy storage material and heat insulation
Proteins
Composed of amino acids connected together by peptide bond
Either a structural molecule or one with enzymatic functions
1o, 2o, 3o, 4o forms
Primary Form
Secondary Form
Tertiary Form
Nucleic Acids
Building blocks: nucleotides Form the genetic material of living systems DNA or RNA In eukaryotic systems, dsDNA are coiled
around histone proteins which become visible during cell division as chromosomes
Nucleotide molecule
Central Dogma of Genetics