Transcript Biopolymers

Top 10 Inventions of The Millennium
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Eraser
Hay
The Stirrup
Reading Glasses
Classical Music
Birth control pills
Transistor
Sodium Polyacrylate Applications
• Absorbs 80x its
molecular weight in
water
• Used to fight forest
fires
• Assists in germinating
seeds in arid/dry
environments
Why Does Sodium Polyacrylate Work?
• Individual sodium
polyacrylate
molecules are
virtually useless
• Connected into long
chains, water
molecules are
trapped between
sodium atoms
Polyethylene
• Arrangement of
styrene units into long
chains
• Allows strength in
longitudinal directions
• Lack of connections
between chains
makes lateral aspects
weak
What Is A Polymer?
Polymers Defined
• Substances made of
three or more
identical units
• The individual unit is
called a monomer;
two units are called
dimers
• As more monomers
are linked, the
properties of the
substance changes
Gunther VonHagens
1993 Hamburg Exhibition of Polymer Art
The Body As Polymer
Four Classes of Biopolymers
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Carbohydrates
Lipids
Nucleic Acids
Proteins
Organic v. Inorganic
• INORGANIC
• Lack the element
carbon
• Ex: NaCl, H20, HF
• ORGANIC
• Contains the element
carbon
• Ex: CO2, C6H12O6
Why Are All Four Biopolymer
Classes Organic?
The Molecular Architecture of Carbon
• High abundance in
biosphere
• Tetravalent electron
arrangement
(4 e- in 2nd valence shell)
• Moderate
electronegativity
means carbon is
unlikely to form ionic
bonds
Carbon The Compromiser
• Carbon shares 4 pairs
of electrons with other
atoms covalently
• This high number of
bonds means many
other atoms can be
linked to carbon
• Covalent bonds
useful in biopolymers
for resisting entropy
• Silicon is also tetravalent
• Silicon (in the form of silica) is frequently
incorporated into living organisms as crystals,
spikes or spines
• However, its lower abundance in the lithosphere
may explain carbon’s dominance
ISOMERIZATION
• Because carbon can
form so many covalent
bonds, substances with
many carbon atoms can
be arranged in many
ways
• Isomers are substances
with the same number
and type of atoms but a
different structural
arrangement/formula
Polymerization Reactions
Polymerization By Condensation
• A hydrogen atom (H) is
removed from one
monomer
• A hydroxyl (-OH) group
is removed from the other
monomer
• Hydrogen and hydroxyl
join to form water
• The remaining monomers
are covalently linked to
form a dimer
Dehydration Synthesis Kinematics
• Energy required to
make bonds form
• This is called an
ENDERGONIC
reaction
• About 200mL of
water/day is
synthesized in the
human body as a
result of endergonic
reactions
HYDROLYSIS
• Literally means
“to split using water”
• The converse of
dehydration synthesis
• A water molecule
splits into H and OHgroups
• The polymer is
divided into
monomers
The Kinematics of Hydrolysis
• Since the two
monomers have less
potential energy than
the original polymer,
energy is “released”
• This is called an
EXERGONIC reaction
• Hydrolysis requires
energy to be put in at
the start but more
energy is freed at the
end
If all biopolymers are constructed
and destructed in the same way,
what makes them different?
Different Organic Substances Have
Different Functional Groups
Carbohydrates
General Characteristics of
Carbohydrates
• Literally means ‘water added to carbon”
• Contains ONLY carbon, hydrogen and
oxygen atoms in empirical formula
• Ratio of hydrogen to oxygen in empirical
formulae is generally 2:1 (i.e. C6H12O6)
• Have caloric value of appx. 4 cal/gram
• May be used for energy flow or structure
Monosaccharides
• Literally translates as
“single sugars”
• Monomers/building
blocks of
carbohydrate
polymers
• Three different
forms/isomers:
glucose, fructose and
galactose
Glucose
• Need 9grams/15
minutes of
metabolism in
bloodstream
• Can only be let into
cells via the action of
the hormone insulin
• Does not taste sweet
Fructose
• Common natural
sugar found in fruits
and honey
• Does taste sweet
Glucose v. Fructose
Glucose v. Galactose
Disaccharides
• “Double sugars”
• Formed from the
condensation
reaction between two
monosaccharides
• Water is removed as
a result of
dehydration synthesis
• Examples: Maltose,
Lactose, Sucrose
The bond between monosaccharides is
called a GLYCOSIDIC linkage
Sucrose
• Formed from
condensation of
glucose and fructose
• Table sugar
• Does taste sweet
Lactose
• Formed by linking
glucose to galactose
• 20% of U.S.
population cannot
hydrolyze the
glycosidic linkage in
lactose
• Lactose intolerance
Maltose
• Formed by linking two
glucose units together
• Common
disaccharide in plants
as intermediate
storage form of
glucose made in
photosynthesis
• Does not taste sweet
• Starches consist of
hundreds of glucose
units connected with
an alpha glycosidic
linkage
• Cellulose contains
equal numbers of
glucose units but has a
beta glycosidic
linkage
• The beta linkage is
indigestible in most
organisms without the
proper enzymes
Characteristics of Proteins
• Contain carbon, hydrogen, oxygen and
nitrogen atoms
• Are generally used for structural purposes
in living organisms but may also be used
for energy flow
• 4 cal/gram if used for metabolism
• Highly folded structures held in place with
combination of strong covalent bonds and
weak intermolecular forces
There are 20 different Amino Acids:
The building blocks of proteins
Amino Acid Form & Function
• Contain CARBOXYL
(COOH) and AMINE
functional groups
• The 20 A.A. differ in the
structure and complexity
of their side groups (R-)
• 16 A.A. synthesized in
body / 4 must come from
diet
• All 20 needed to create
the proteins necessary for
life
Phenylalanine
Tryptophan
Synthesis of A Dipeptide
• Two A.A. monomers are
joined by removing the
hydrogen from one
amine group and a
hydroxide ion from the
carboxyl group of
another atom
• One water molecule is
formed/condensed
• The resulting linkage is a
strong bond called a
PEPTIDE BOND
Polypeptide Formation
Levels of Peptide Structure
• Primary: Sequence of A.A. held by
peptide bonds
• Secondary: Coiled A.A. chain held by
disulfide and hydrogen bonds
• Tertiary: Folded coil of A.A. held by
hydrogen bonds
• Quaternary: Globular shape held by
hydrogen, VanderWaal and other
intermolecular forces
Ex: Levels of Structure In Proteins
Preserving this quaternary
structure is one of the prime
components of homeostasis
LIPIDS
Characteristics of Lipids
• Comprised of only carbon, hydrogen and
oxygen atoms
• Ratio of hydrogen to oxygen is always
GREATER than 2:1
• Caloric value of lipids is appx. 9 cal/gram
• Lipids good for long-term storage of
energy due to non-polar structure, high
caloric value and density
Lipids are comprised of 3 fatty acid
monomers linked to a glycerol molecule
Bonding In Fats
• Each fatty acid loses a
hydroxyl (OH-) group
• The glycerol backbone
loses 3 hydrogen atoms
• Three water molecules
are condensed
• The fatty acids and
glycerol combine as an
ESTER LINKAGE
Saturated v. Unsaturated Fats
• Saturated Fats
• All carbon atoms are
bonded to four other
atoms via single bonds
• Saturated fats tend to be
solid and dense
• Often derived from
animals
• Atherosclerosis and
obesity may result from
overconsumption
• Unsaturated Fats
• Some carbon atoms
share more than one pair
of electrons
• This is called a double
bond or unsaturation
• Unsaturated fats tend to
be liquids/oils and often
come from plants or
aquatic animals
Saturated, Unsaturated and
Polyunsaturated Fats
Excess saturated fat is stored in
large cells called Adipocytes
Fatty acids may also combine with charged
phosphate groups to create phospholipids, which
simultaneously attract and repel water
If heated, the glycerol in fats is changed into
a carcinogen called acrolein which causes
digestive distress/heartburn