The Chemistry of Life
Atoms and Their Interactions
Water and Diffusion
Life Substances
AtomsSmallest particle of an element that
has the characteristics of an element.
Basic unit of matter
Atomos = (greek) unable to be cut
Atomic Structure and Subatomic Particles
Nucleus—strong forces bind protons and neutrons at center of the atom;
Protons - + charged particlesNeutrons - particles with no charge
Electrons - charged particle; 1/1840 mass of proton; constantly in motion in space surrounding nucleus; attracted to protons in nucleus
Electron Energy Levels
Electrons travel around the nucleus in certain regions known as Energy Levels.
The innermost level (small) maximum of 2 electrons.
2nd level (larger)-up to 8
3rd level-up to18 electrons.
Element
Pure substance that consists entirely of one type of atom.
Earth
•Between 88 – 94 elements
occur naturally
•About two dozen found living organisms)
Trace Elements
Elements in living things in very small amounts.
(help maintaining healthy cells)
Examples: iron and magnesium
What is the most abundant element that exist in living things? (Number)
Most abundant weight
Periodic Table of ElementsPeriodic-Elements in same group have similar chemical and physical
properties
• Elements and symbols are organized
• Rows-period; Same number of electron shells
• Vertical-groups; Electrons in outer energy level
Element
Neutral Atoms# of Electrons = # of protons therefore have no net charge.
Same # Electrons = same chemical properties
Mass number= Protons + Neutrons
Isotopes
Example: Carbon-14 (6 +, 6 -) is an isotope of carbon,
•8 neutrons instead of 6 neutrons
•Carbon 13- 7 neutrons, 6 protons
•Isotopes-number of electrons same chemical properties
Atoms of the same elements that have different numbers of neutrons.
Atomic Mass= Average of the masses of an element’s isotopes.
RADIO ISOTOPES
•Isotopes that have unstable nuclei and break down at a constant rate over time. (radiation)•Medical•Smoke detectors•Archeological dating
Radioisotopes in Medicine
• Detect and treat cance• Kill bacteria that causes food to spoil• “Tracers” to follow movement of substances within an organism.
Compounds
• Substance formed when atoms of two or more elements are chemically combined in definite proportions.
• Example: H2O (2:1), NaCl (1:1)
Compound Unique Characteristics
• Specific combination of elements in a fixed ratio.
• Chemically and physically different than elements its comprised. (eg. Water different than H and O)
• Cannot be broken down into simpler compounds or elements by physical means
Chemical Bonds
• Force that holds substances together
• Stability
• Forming and breaking bonds-provides energy for growth, development, adaptation, and reproduction
Ionic Bonds
Electrical attraction b/w 2 oppositely charged atoms or group of atoms.
Ion
An atom (or group of atoms) gains or loses electrons has an electrical
charge.
An ION is a charged particle.
VAN DER WAALS FORCES-EX. HYDROGEN BONDS
Molecules close together, slight attraction can form b/w oppositely charged portion of nearby molecules- the intermolecular forces
--Helps form water droplets, geckos climb using structures on toes and atoms on surface climbing.
Covalent Bonds
A chemical bond formed when two atoms combine by sharing electrons.
Molecule
Substances with covalent bonds and having no overall charge.
Most compounds in living things.
Example : Water, DNA
Covalent Bonds• Single-Each atom shares one electron
• Double- Each atom shares two electrons
• Triple- Each atom shares three electrons
Chemical Reactionsprocess that changes, or transforms, one set of
chemicals into another
Chemical bonds formed and broken
Metabolism
All chemical reactions that occur within an organism
•Responsible for break down and building of molecules
How do I know chemical reaction has occurred?
• Color change - new substances might reflect different colors of light.
• Heat change - the container may get hotter or colder.
• Gas produced - bubbles or smoke may be observed.
• Precipitate formed - an insoluble solid might form in a liquid.
Reactants
Substances that undergo chemical reactions.
PRODUCTS
a substance obtained from another substance through chemical change
Energy in reactions
• Energy changes- Some reactions release energy (spontaneous, form of heat), others absorb energy (will not happen w/o energy)
• Energy Sources-sun >plants>animals
• Activation Energy- Energy needed to get reaction started.
Mixture
A material composed of 2 or more elements or compounds that are
physically mixed but not chemically combined
Solution—A mixture in which all the components are equally
distributed (salt water solution)
Solute—Substance being dissolved. (salt)
Solvent—Substance that does the dissolving. (water)
Universal solvent is water!!
Suspension
Mixture containing non dissolved particles distributed within a solid,
liquid or gas.
Examples: Orange Juice, Blood, Salad Dressing.
Colloid
A thick substance formed when very fine particles (such as large molecules) that cannot be dissolved stay scattered throughout liquid,
solid, or gas without sinking.
Examples: Gelatin, Toothpaste, Shaving Cream, Smoke and Milk
Tyndall Effect
Scattering of light by colloidally dispersed particles.
Detected with the aid of a light beam.
Water
• Liquid most of Earth’s surface• Expands slightly as it changes from liquid to
solid• Covers 75% of Earth’s surface • Most abundant compound in nearly all living
organisms• Water resist temperature change
Water continued….• Polar Molecule—Due to an uneven
distribution of electrons, water molecules are slightly charged on each end. – Oxygen has a slight negative charge
– Hydrogen have a slight positive charge.
• Strong attraction between water and other molecules; the universal solvent.
• Dissolve ionic compounds, as well as sugars.
Hydrogen BondsWeak chemical bond formed by the attraction of the hydrogen atoms to
other negatively charged atoms.
weak "hydrogen" bonds in water partially get their identity
from stronger "covalent" bonds in the H2O molecule
Cohesion
Attraction between molecules of the same substance
•Water forms beads on smooth surface
•reason insects can walk on water
Surface Tension
How difficult it is to stretch or break the surface of a liquid.
•Water has a high surface tension b/c of cohesion of hydrogen bonds.
Adhesion
Attraction b/w molecules of different substances.
Eg. Water molecule in a graduated cylinder
Capillary Action
Unique property of being able to creep up thin tubes.
Water tension and capillary action allow water to move from soil to top of trees.
Heat Capacity
• Result of hydrogen bonds b/w water molecules is that it takes large amount of heat energy to cause molecules to move faster– Large bodies of water absorb large amounts of
heat w/ small changes in temperature– Organisms in water are protected from drastic
change– Cell level-water absorbs heat produced by cell
processes, regulating cell temperatures
pH-Acids and Bases
pH Scale—A measurement system that indicates the relative concentrations of hydrogen and hydroxide ions.
Acids
Compounds that release hydrogen ions (H+) into a solution.
Acids have a pH between 0-6
Bases
Compounds that release hydroxide ions (OH-) into a solution.
Bases have a pH between 8-14
Neutral
strong acid (H+) + strong base (OH-) =
water and salt.
pH of 7
Buffers
Weak acids or bases that can react with strong acids or bases to prevent
sharp, sudden changes in pH
Diffusion
Net movement of particles from an area of higher concentration to an
area of lower concentration.
Factors that influence rate of diffusion
• Concentration of substance. The more concentrated the substance, the more rapid diffusion.
• Temperature—The higher the temperature the more rapid the molecules will move and the speedier diffusion will be.
• Pressure—As pressure increase, the more rapid molecular movement, the speedier diffusion will occur.
Result of Diffusion
Dynamic Equilibrium—A condition in which there is a continuous
movement of particles (Brownian Motion) but no overall change in
concentration.
Concentration Gradient
Differences in concentration of substances across space.
Molecules of Life
Organic (come from organisms)
• Chemical compounds that exist or derived from plants or animals, (all carbon compounds)
• No manufactured chemicals
Carbon• 2 electrons 1st energy level,
• 4 electrons on outer energy level
• 6 protons, 6 neutrons
• Bonds well with other carbon atoms, as well as with other elements.
• Single, double and triple bonds
Single, Double, Triple Bonds
Carbon continued…
• Straight chains, branched chains, or rings.• Isomers—compounds that have the same simple
formula but different three-dimensional structure.
Molecular Chains
Macromolecules—Large molecules
Example Proteins
(meros-part)
Polymer—large molecule formed when many smaller molecules bond
together. (repeating units)
Monomer—simple compound whose molecules can join together to form
polymers
Condensation Reactionsalias: Dehydration synthesis
A chemical reaction by which polymers are formed.
Water is formed
Hydrolysis
•A method by which polymers can be broken apart.
•H+ and OH- from water attach to bonds between subunits that make up polymer, thus breaking the
polymer.
Four Types of Organic Compounds
Carbohydrates
Lipids
Proteins
Nucleic Acids
CarbohydratesAn organic compound composed of Carbon, Hydrogen, and Oxygen
(CHO Family).
2 hydrogen:1Oxygen:1Carbon
Source of energy; structural
Types of CarbohydratesMonosaccharides
DisaccharidesPolysaccharides
Monosaccharide
Simple sugar Example: Fructose and Glucose
Disaccharide
Two monosaccharides linked together;
A two-sugar carbohydrate.
Example:
Glucose and Fructose Sucrose (condensation reaction)
Polysaccharides
Largest carbohydrate molecules; polymers composed of many
monosaccharide sub units.
Examples: Starch (Food storage in plants)
Glycogen (form in which animals store food in their liver),Cellulose (in plant cell wall, gives structural support.
SOURCES OF CARBOHYDRATES
Cereals
Breads
Fruits
Vegetables
Lipids• A large portion (much greater then 2 to 1) of C-H
bonds and less oxygen than carbohydrates (CHO family).
• Fats and oils• Insoluble (non-polar, no charge, therefore not
attracted)• Cells uses: Energy, storage, insulation, and
protective coatings.• Useful in food preparation.• Subunits: Glycerol, fatty acids.Sources: nuts, butter, vegetable oil, and cheeses
Phospholipids- contain glycerol, two fatty acids, and a phosphate group, and are important in cell structures.
Steroids- are complex ring structures, and include cholesterol, which is used to synthesize the sex
hormones.
Saturated Fats/ Unsaturated Fats
Fatty acids with hydrogen at every position along the carbon chain are saturated
Fatty Acids with one or more double bonds are called unsaturated fats
Proteins
A large, complex polymer composed of carbon, hydrogen, oxygen, nitrogen and usually sulfur.
(CHO + NS)
•structure for tissues and organs
• metabolism (all of the body’s chemical reactions)
SOURCES OF PROTEINS
Soybeans
Milk products
Meat
Eggs
Fish
Beans
Amino Acids• Basic building blocks of proteins.• 20 common amino acids • AA combinations can make thousands of proteins
(vary more in structure then any other organic molecule)
• Amino Acids link together when a (+H) from one amino acid and an (-OH) group from another amino acid are removed to form a water molecule.
• Covalent bond formed between the two amino acids--peptide bond.
• # amino acids and order determine protein.
Types of Proteins/ FunctionsEnzymes-catalyze chemical reactions
Antibodies-Immune System Hemoglobin-Oxygen transport in blood
Hormones-regulate metabolismActin and Myosin -Muscle proteins
Glycoproteins-Cell membraneKeratin and Collagen - structural, or
support proteins.
catalyst
Substances that speeds up the rate of chemical reactions
Proteins that act as biological catalyst (lower activation energy)
• Site where reactants brought together to react
• Reactants are call substrates
• The products are released
• Site where substrate binds to enzyme is called active site.
• Temperature, pH and regulatory molecules can affect the activity of enzymes.
Nucleic Acids
A complex macromolecule that stores cellular information in the form of a
code.
Nucleotides• Nucleic acids are polymers made of smaller
subunits called nucleotides.
Nucleic Acids
Consist of carbon, hydrogen, oxygen, nitrogen, and phosphorus atoms
arranged in three groups—A nitrogen base, simple sugar (ribose) and
phosphate group.Examples : DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)
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