Atoms-- “Unable to be cut” Protons (+) charged Neutrons (o) charged Electrons (-) charged with...
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The chemistry of Life
Atoms-- “Unable to be cut” Protons (+) charged Neutrons (o) charged Electrons (-) charged with 1/1840 the mass of a proton. They are in constant motion
Atoms-- Unable to be cut Protons (+) charged Neutrons (o)
charged Electrons (-) charged with 1/1840 the mass of a proton.
They are in constant motion Have about the same mass.
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Element Pure substance that consits entirely of one type of
atom.
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Organic chemistry- chemistry of carbon compounds. Biochemistry
is a branch of organic chemistry which attempts to explain the
chemistry in living organisms.
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The majority of organic molecules can be classified into one of
the four: - Carbohydrates - Lipids - Proteins - Nucleic acids
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3.1 Chemical elements and water What elements (most common) are
found in living organisms?
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- Carbon - Hydrogen - Oxygen - Nitrogen These elements are used
in the molecular structures of all carbohydrates, proteins, lipids,
and nucleic acids.
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BUT Living organisms contain a variety of other elements which
are extremely important, but are less common.
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Sulfur Some amino acids contain sulfur and can form a bond with
another amino acid which also contains sulfur. These connections
are called disulfide bridges. They can occur within a polypeptide
chain which causes folding of the chain. They can also occur
between polypeptide chains and keep the chains together.
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Phosphorus A schematic diagram of a molecule of ATP. Note that
the three phosphates have high energy bonds between them. Each
phosphate contains the elements phosphorus and oxygen.
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Calcium Calcium is needed to form bone tissue. In the figure
shows normal bone on the left and bone with osteoporosis on the
right. Notice the decrease in bone material and hence in
strength.
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Iron In the figure shows the structure of one of the four
polypeptide chains that makes up hemoglobin. Each chain has a heme
group containing iron associated with it. The heme group containing
the iron is indicated by a pointer. Iron is also important in
myoglobin and cytochromes.
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SODIUM During a nerve impulse, in the first part of an action
potential, sodium channels open across the plasma membrane and
sodium will diffuse into the neuron.
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Structure of water - Is the solvent of life. - All cells have
water within (cytoplasm) and water in the surroundig environment
(intercellular fluir, pond water, etc.)
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A typical person could survive for about a month without food.
They would survive only a week or less without water.
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Covalent Bonds Are formed when electrons are shared between
atoms. Shared electrons by atoms instead of being transferred.
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A simulation of polar covalent bonding in the H 2 O molecule
(Only valence electrons are shown)
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Polarity Oxygen atom has a stronger attraction for electrons
than does the hydrogen atom with a single proton in its nucleus. In
the oxygen end of the molecule it has a slight negative charge and
the hydrogen end of the molecule has a positive charge.
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A water molecule is polar because there is an uneven
distribution of electrons between the oxygen and hydrogen
atoms.
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Hydrogen Bonds Because of their partial positive and negative
charges, polar molecules such as water can attract each other.
Hydrogen bonds are not as strong as covalent bonds or ionic bonds,
but waters ability to form multiple hydrogen bonds is responsible
for its properties.
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Thermal properties Water can absorb or give off a great deal of
heat without changing temperature greatly.
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Think of a body of water on a very cold night; even though the
air may be very cold, the body of water is relatively stable in
temperature.
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All living things are composed of a great deal of water and
thus you can think of your water content as a temperature
stabilizer.
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Water also has a high heat of caporization. This means that
water abosrbs a great deal of heat when it evaporates. This
mechanism is used by us to cool down.
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Heat turns water molecules from liquid to vapor from your body
and thus sweating not only makes you feel cooler, it really does
lower your temperature.
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Cohesion An attraction between molecules of the same substance.
Water cohesion causes molecules on the surface of water to be drawn
inward.
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When water cools below the freezing point, molecular motion has
slowed to the point where these polar attractions become locked
into place and an ice crystal forms.
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Cohesion between liquid water molecules explain a variety of
events, including: Why water forms into droplets when spilled Why
water has a surface tension that allows some organisms to walk on
water, somo run How water is able to move as a column in the
vascular tissue of plants Why water has a high heat capacity and
high heat of vaporization as discussed earlier.
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Adhesion Attraction between molecules of different
substances.
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Solvent properties Water is an excellent solvent of other polar
molecules. Like disolves like The majority of molecules typically
found inside and outside of most cells are polar; including
carbohydrates, proteins, and nucleic acids. Lipids are non- polar
BUT most organisms have special strategies to deal with the
transport and biochemistry of lipids.
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Water is an excellent solvent for biochemically important
molecules, it is also the medium in which most of the biochemistry
of a cell occurs. A cell contains a wide variety of fluids, all of
which are primarily water. We refer to such solutions as aqueous
solutions.
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Aqueous solutionLocationCommon reactions CytioplasmFluid inside
cell but outside organelles Glycolysis/ protein synthesis reactions
NucleoplasmFluid inside nuclear membrane DNA replication/
transcription StromaFluid inside chloroplast membrane Light-
independent reactions of photosynthesis Blood plasmaFluid in
arteries, veins and capillaries Loading and unloading of
respiratory gases/ clotting
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Examples of water as a solvent in plants and animals The
properties of water make it an excellent medium for transport.
Vascular tissue in plants carries water and a variety of dissolved
substances.
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Xylem carries water and dissolved minerals up from the root
system to the leaves of a plant. Phloem then transports dissolved
sugars from the leaves to the stems, roots and flowers of a
plant.
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Blood is the most common transport medium in animals and is
largely made up of water. Blood is transport medium for red blood
cells, white blood cells, platelets and a wide variety of dissolved
molecules.
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The liquid portion of blood plasma are: - glucose (blood sugar)
- amino acids - fibrinogen (protein involved in blood clotting) -
hydrogencarbonate ions (as a means of transporting CO 2 ).