Water: A special molecule The solvent in cells, tissues and
organs is water. Four special properties of water are: 1. Hydrogen
bonding Effects: cohesion, adhesion, surface tension. More energy
is needed to break hydrogen bonds than other intermolecular bonds,
which gives water a high specific heat capacity. 2. Density
Effects: Ice is the only solid that floats in its liquid! This
insulates water under ice.
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Water: A special molecule 3. Polar nature of the bond Effects:
as a solvent, water allows polar molecules and ionic compounds to
dissolve due to waters polarity. 4. Dissociation of intramolecular
bonds Effects: 1 in 10 7 water molecules dissociates to form H +
and OH - ions. This is a pH of 7 = NEUTRAL.
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Functional Groups Functional groups are parts of larger
molecules. They greatly influence biological reactivity because
they have negative or positive regions that react to form
bonds.
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Draw the structural formula.
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Biochemical Reactions that Make and Break Molecules
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Macromolecules Macromolecules are large organic molecules. The
four main types of macromolecules are 1.Carbohydrates sugars and
starches 2.Lipids fats and hormones 3.Proteins enzymes and
structures 4.Nucleic acids DNA and RNA Macromolecules are also
called polymers.
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Monomers and Polymers mono means one mer means unit So a single
unit of a large molecule is a monomer poly means many So a polymer
is a large molecule made of many monomers For example: sugar +
sugar starch amino acid + amino acid protein
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Five Major Biochemical Reactions Making and breaking bonds is
important to forming polymers from monomers. 1.Condensation or
dehydration synthesis 2.Hydrolysis or decomposition with water
3.Neutralization of acids and bases 4.Redox or electron trading
5.Phosphorylation or adding a phosphate group
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1. Condensation Reactions A condensation reaction joins
monomers to form polymers. When a bond is formed between two
monomers a water molecule is also produced. This reaction is also
called dehydration synthesis. + + H 2 0 Example: glucose + fructose
sucrose + H 2 0
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2. Hydrolysis Reactions A hydrolysis reaction breaks a polymer
into monomers. Water is added to a molecule which causes a bond to
break. The H+ is added to one monomer and the OH- to the other
monomer. Example: sucrose + H 2 0 glucose + fructose
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3. Neutralization Reactions Acids have a -COOH or H + group.
Bases have a OH or NH 2 group. A neutralization reaction occurs
when acids and bases react to produce a salt and water. Buffers are
molecules that react to minimize pH changes in a cell. Buffers
absorb excess H+ (acids) or OH- (bases)
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4. Redox Reactions Redox stands for reduction oxidation
reactions LEO goes GER Loss of Electrons is Oxidation Gain of
Electrons is Reduction Common in metabolic reactions like
photosynthesis and cellular respiration. The electrons are carrying
energy.
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5a. Substrate-level Phosphorylation ATP, adenosine
triphosphate, is the energy molecule of all cells. The bond formed
by adding a 3 rd phosphate group to adenosine diphosphate (ADP) is
an important energy storage location. Substrate-level
phosphorylation uses the energy released from breaking a phosphate
group off another molecule to attach the phosphate to ADP to form
ATP.
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5b. Oxidative phosphorylation Oxidative phosphorylation is a
metabolic reaction that uses energy released by the oxidation of
glucose to produce ATP in cellular respiration.
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5c. Photophosphorylation Photophosphorylation is the production
of ATP using the energy of sunlight during photosynthesis.