CHEMISTRY OF LIFE
A.
Inorganic compounds—without carbon
1.
Water (H2O)—most important inorganic compound. Many of its unique properties
result because water molecules form hydrogen bonds with each other. A
hydrogen bond is a weak bond between two molecules resulting from an electrostatic
attraction between a proton in one molecule and an electronegative atom in the other.
a.
b.
c.
excellent solvent (universal)—because it is polar
covalent, other polar molecules and compounds
dissolve in it
high heat capacity
Water molecules are attracted to one another
(cohesion)
d.
2.
Water molecules stick to other polar substances
(adhesion)
e.
Ice floats—when water freezes hydrogen bonds
lock water molecules into a crystal structure that
has many open spaces
Acids and bases—measured on pH scale. Fluctuations in
pH can change the rate and nature of internal chemical
reactions.
a.
Acid—strong acids, pH near 0. Characterized by
b.
c.
B.
an abundance of H30+ (hydronium) ions.
Base—strong bases pH near 14. Characterized by
an abundance of OH- (hydroxide) ions.
Neutral—pH of 7 (distilled water)
Organic compounds—compounds containing carbon (sometimes called biomolecules).
Most composed of basic units that repeat. These units are called monomers. Polymers are
formed from the condensation of many monomers and are called macromolecules.
1.
Carbohydrates—contain carbon, hydrogen, and oxygen (have ratio of 2 hydrogen
atoms and 1 oxygen atom per carbon atom). The main source of energy for humans
and used as structural compounds.
a.
Monosaccharides—simple sugars; monomers of carbohydrates. Common
monosaccharides include glucose, fructose, and galactose. All have the
simple formula of C6H12O6.
b.
Disaccharides—double sugars. Formed from the
condensation of two monosaccharides. Examples
include:
(1)
Maltose (malt sugar)—glucose + glucose
(2)
(3)
c.
Polysaccharides—complex sugars. Composed
of long chains of monosaccharides.
(1)
Starch—plant energy storage, polymer of
glucose. Forms single line chains of
molecules.
(2)
Glycogen—animal energy storage (in liver and between
(3)
(4)
2.
Lactose (milk sugar)—glucose + galactose
Sucrose (table sugar)—glucose + fructose
muscle fibers), polymer of glucose. Forms branching chains of
molecules.
Cellulose—indigestible, dietary fiber for
animals. Forms the cell wall of many plant
cells.
Chitin—makes up the exoskeleton of arthropods and cell walls of
fungi.
Lipids—also contain carbon, hydrogen, and oxygen, but in a different ratio
than carbohydrates. Include fats, oils, waxes, and steroids (fat based
hormones). More complex than carbohydrates. Triglycerides (found in fats
and oils) are made of glycerol + three fatty acids. More energy per gram than
carbohydrates. Used for long term energy storage in humans, cell
membranes, and in the nervous system.
3.
Proteins—basic building blocks of tissues. Contain carbon, hydrogen, and oxygen as
well as nitrogen and sulfur. Made of monomers called amino acids. Used
structurally and as biological catalysts called enzymes.
a.
Amino acids—monomers of proteins; made of an
organic acid or carboxyl group (COOH), amino
group (NH2), single carbon atom attached to
hydrogen, and an R-group. Each of the twenty
(20) different amino acid differs in the R-group.
b.
c.
Dipeptides—two amino acids joined by peptide
bonds.
Polypeptides—three or more amino acids joined
by peptide bonds. All proteins consist of these.
The sequence of amino acids determines the type
of protein. Shapes of protein molecules vary with
the sequence of the amino acids and determine
their properties.
Enzymes—proteins that act as biological catalysts.
a.
Names of many enzymes end in “ase”. Examples include sucrase
(works on sucrose) and maltase (works on maltose).
b.
c.
Each enzyme works on a specific substrate.
They lower the amount of activation energy needed to start a
chemical reaction, thus speeding up chemical reactions; used over and
over again.
d.
Vitamins may act as co-enzymes.
4. Nucleic acids—carry instructions for cellular activity.
a.
DNA (deoxyribonucleic acid)—records
instructions and transmits them from generation to
generation. Found primarily in the nucleus of the
cell.
b.
RNA (ribonucleic acid)—reads and carries out
instructions. Found in nucleus and cytoplasm of
the cell.
c.
ATP—high energy compound
Both are made of complex monomers called nucleotides
CELLS & ENERGY
ATP—adenosine tri-phosphate (a type of nucleic acid)
1.
2.
3.
4.
Supplies energy for endergonic reactions in organisms
Consists of a nitrogen base (adenine), sugar (ribose), and three phosphate groups
Energy is stored in bonds between phosphate groups and released for use when bonds are
broken
Cyclic in nature
Photosynthesis—captures energy from light and stores it in the glucose molecule. The simplest
formula for photosynthesis is:
6CO2 + 6H2O
C6H12O6 + 6O2
Two phases:
1. Light dependent reactions—occur only in light
A.
B.
C.
D.
2.
Occurs in the grana of the chloroplasts.
The electron transport chain which occurs in the thylakoid membranes of the grana
produces ATP for use in the light independent reactions.
Water molecule split in the electron transport chain occurring in the thylakoid membranes.
This process produces hydrogen atoms which are combined with NADP+ forming NADPH
to be used in the light independent reactions.
Oxygen released into the atmosphere.
Light independent reactions (also called the Calvin Cycle)—occur in light or darkness
A.
B.
C.
D.
Occurs in the stroma of the chloroplasts.
Energy from ATP and NADPH produced in the light dependent reactions used in this
stage.
Glucose is created and stored by plant for later use.
Carbon dioxide uptake occurs in this stage.
Cell respiration—releases energy from glucose, a total of 38 ATP molecules per molecule of glucose.
ATP is adenosine tri-phosphate, a high-energy compound and the only compound that can be used
by the body for energy. The formula for cell respiration is:
C6H12O6 + 6O2
6CO2 + 6H2O + 38 ATP
Two phases of cell respiration:
1.
Glycolysis—(anaerobic respiration—w/out oxygen) process that occurs in the cytoplasm of
the cell
A.
B.
C.
Glucose molecule split into two molecules of pyruvic acid
Net production—2 ATP/glucose molecule
Fermentation—follows glycolysis if no oxygen is present in the cell.
Two types:
(1)
Alcoholic fermentation—most microorganisms produce ethyl alcohol and carbon
dioxide
(2)
Lactic acid fermentation—most animal cells and some microorganisms produce
lactic acid
2. Aerobic respiration—occurs in the mitochondria of eukaryotes if oxygen is present in the cell
A.
Three parts—net production 36 ATP/glucose molecule
(1)
(2)
(3)
B.
Pyruvic acid conversion (to acetyl coA)—O ATP/glucose molecule
Citric Acid Cycle (Krebs Cycle)—2 ATP/glucose molecule. This cycle turns twice
for each molecule of glucose going through cell respiration, therefore one ATP is
produced per turn.
Electron transport chain (chemical reactions catalyzed by enzymes embedded in
the christae of the mitochondria)—34 ATP/glucose molecule
6 molecules of carbon dioxide and 6 molecules of water released
TOTAL NET ATP PRODUCTION FOR CELL RESPIRATION—38 ATP/GLUCOSE MOLECULE
Electron Transport Chain in Photosynthesis
Electron Transport Chain in Cell Respiration