The Chemistry of Life

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Transcript The Chemistry of Life

The Chemistry of Life
Atoms and Their Interactions
Water and Diffusion
Life Substances
Atoms
Smallest 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 particles
Neutrons - 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 Elements
Periodic-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
Atoms of the same elements that have different numbers of
neutrons.
Atomic Mass= Average of the masses of an element’s 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
•Isotopes that have unstable nuclei and break down at a constant rate over
time. (radiation)
•Medical
•Smoke detectors
•Archeological dating
RADIO ISOTOPES
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.
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.
VAN DER WAALS FORCES
-EX. HYDROGEN BONDS
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 Reactions
process 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.
a substance obtained from another substance through
chemical change
PRODUCTS
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 Bonds
Weak 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 Reactions
alias: 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
Carbohydrates
An organic compound composed of
Carbon, Hydrogen, and Oxygen
(CHO Family).
2 hydrogen:1Oxygen:1Carbon
Source of energy; structural
Types of Carbohydrates
Monosaccharides
Disaccharides
Polysaccharides
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.
Cereals
Breads
Fruits
Vegetables
SOURCES OF
CARBOHYDRATES
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)
Soybeans
Milk products
Meat
Eggs
Fish
Beans
SOURCES OF PROTEINS
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/ Functions
Enzymes-catalyze chemical reactions
Antibodies-Immune System
Hemoglobin-Oxygen transport in blood
Hormones-regulate metabolism
Actin and Myosin -Muscle proteins
Glycoproteins-Cell membrane
Keratin 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)