Transcript Macromolecules

Macromolecules
 Large Molecules
 Macromolecules are formed when
monomers are linked together to
form longer chains called polymers.
 The same process of making and
breaking polymers is found in all
living organisms.
Condensation Reaction
 Consider some generic monomers with OH groups on
their ends.
 These monomers can be linked together by a process
called dehydration synthesis (also called a
condensation reaction) in which a covalent bond
is formed between the two monomers while a water
molecule is also formed from the OH groups.
 This reaction is catalyzed by a polymerase enzyme.
 This same type of condensation reaction can occur to
form many kinds of polymers, from proteins to
carbohydrates, nucleic acids to triglycerides.
Hydrolysis Reactions
 Polymers of all sorts can be broken
apart by hydrolysis reactions. In
hydrolysis the addition of a water
molecule (with the help of a
hydrolase enzyme) breaks the
covalent bond holding the monomers
together.
Four major types of
Macromolecules
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Lipids
Carbohydrates
Nucleic Acids
Proteins
Four major types of
Macromolecules
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Lipids
Carbohydrates
Nucleic Acids
Proteins
Diverse groups of
molecules in
Sugars
nonpolymorphic
Nucleotides
form
Amino Acids
Proteins
 Proteins consist of one or more polymers
called polypeptides, which are made by
linking amino acids together with peptide
linkages.
 Peptide linkages are formed through
condensation reactions.
 All proteins are made from the same 20
amino acids.
 Different amino acids have different
chemical properties.
Proteins
 Protein’s primary structure largely
determines its secondary, tertiary
(and quaternary) structure.
 Proteins subjected to extreme
conditions (large changes in pH, high
temperatures, etc.) often denature.
 Proteins act as enzymes, and
catalyze very specific chemical
reactions.
Proteins
Carbohydrates
 Carbohydrates are always
composed of carbon, hydrogen and
oxygen molecules
 Monosaccharides typically have five
or six carbon atoms.
 Monosaccharides can, such as the
ribose and deoxyribose of RNA and
DNA, can serve very important
functions in cells.
Carbohydrates
 Condensation reactions form covalent
bonds between monosaccharides,
called glycosidic linkages.
 Monosaccharides are the monomers
for the larger polysaccharides.
 Polysaccharides play various roles,
from energy storage (starch,
glycogen) to structure (cellulose).
Nucleic Acid
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Two types of nucleic acids:
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DNA
RNA
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the purines
DNA stores the genetic information of organisms; RNA is used to
transfer that information into the amino acid sequences of
proteins.
DNA and RNA are polymers composed of subunits called
nucleotides.
Nucleotides consist of a five-carbon sugar, a phosphate group and
a nitrogenous base.
Five nitrogenous bases found in nucleotides:
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adenine (A)
guanine (G)
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cytosine (C)
thymine (T) (DNA only)
uracil (U) (RNA only)
the pyrimidines
Nucleic Acid
 DNA is transmitted from generation
to generation with high fidelity, and
therefore represents a partial picture
of the history of life.
Nucleic Acid
Lipids
 Lipids constitute a very diverse group of molecules
that all share the property of being hydrophobic.
 Fats and oils are lipids generally associated with
energy storage.
 Fatty acids, which make up fats and oils, can be
saturated or unsaturated, depending on the absence
or presence of double bonded carbon atoms.
 Other types of lipids are used for a other purposes,
including pigmentation (chlorophyll, carotenoids),
repelling water (cutin, suberin, waxes) and signaling
(cholesterol and its derivatives).
Lipids
 Lipids are joined together by ester
linkages.
 Triglyceride is composed of 3 fatty
acid and 1 glycerol molecule
 Fatty acids attach to Glycerol by
covalent ester bond
 Long hydrocarbon chain of each fatty
acid makes the triglyceride molecule
nonpolar and hydrophobic
Lipids
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