Download condensation reaction

THE STRUCTURE AND
FUNCTION OF
MACROMOLECULES
POLYMERS
• POLYMERS- large molecules consisting of
many identical or similar subunits
connected together
• MONOMER- subunits of polymers
• MACROMOLECULES- large organic
polymer
FOUR CLASSES OF
MACROMOLECULES
• CARBOHYDRATES
• LIPIDS
• PROTEINS
• NUCLEIC ACIDS
HOW MACROMOLECULES
ARE MADE
• POLYMERIZATION REACTIONS- Chemical
reactions that link two more small molecules to
form larger molecules with repeating structural
units
• CONDENSATION REACTIONS polymerization reactions during which
monomers are covalently linked, producing net
removal of a water molecule for each covalent
linkage
• ***most polymerization reactions are condesation
reactions
CONDENSATION REACTIONS
• One monomer loses a hydroxyl (-OH) and
the other monomer loses a hydrogen (-H)
• Process requires energy
• Process requires biological catalysts or
enzymes
CONDENSATION
REACTION
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CONDENSATION AND
HYDROLYSIS
HYDROLYSIS
• A REACTION THAT BREAKS COVALENT
BONDS BETWEEN MONOMERS BY THE
ADDITION OF WATER MOLECULES
– A hydrogen from the water bonds to one monomer, and
the hydroxyl bonds the adjacent monomer
– EXAMPLE: digestive enzymes catalyze hydrolytic
reactions which break apart large food molecules into
monomers that can be absorbed in the bloodstream
CARBOHYDRATES
Fuel and Building Material
• SUGARS-the smallest
carbos, serve as fuel and
carbon sources
• CARBOHYDRATESorganic molecules made of
sugars and their polymers
• MONOSACCHARIDESthe building blocks of
carbos-called simple
sugars
monosaccharides
MONOSACCHARIDES
• A simple sugar in which
C,H,O occur in the ration
of (CH20)
– Are major nutrients for
cells; glucose is the most
common
– Can be produced by
photosynthetic organisms
– Store energy in their
chemical bonds which is
harvested by cell respiration
STRAIGHT AND RING
GLUCOSE
• RING FORM USED IN MAKING POLYMERSMORE STABLE
CHARACTERTISTICS OF A
SUGAR
• An -OH group is attached to each carbon except
one, which is double bonded to an oxygen
(carbonyl)
GLUCOSE MOLECULE-NOTICE DOUBLE BOND TO OXYGEN
MORE CHARACTERISTICS
OF MONOSACCHARIDES
• The size of the carbon skeleton varies from three
to seven carbons.
• Spatial arrangement around asymmetric carbons
may vary. For example, glucose and galactose are
enantiomers
• **the small difference between isomers affects
molecular shape which gives each molecule
distinctive biochemical properties
• In aqueous solutions, many monosaccharides from
rings. Chemical equilibrium favors ring structure
DISACCHARIDES
– A DOUBLE SUGAR THAT CONSISTS OF TWO
MONOSACCHARIDES JOINED BY A GLYCOSIDIC
LINKAGE
– GLYCOSIDIC LINKAGE= covalent bond formed by a
condensation reaction between two sugar monomers; for
example maltose
Glucose+ glucose = maltose
Glucose + galactose = lactose
Glucose + fructose = sucrose
POLYSACCHARIDES
• Macromolecules that are polymers of a few hundred or
thousand monosaccharides
– Are formed by linking monomers in enzyme-mediated
condensation reactions
– Have 2 important functions:
– 1) energy storage (starch and glycogen);
– 2) structural support (cellulose and chitin)
POLYSACCHARIDES
(GLYCOGEN)
STORAGE
POLYSACCHARIDES
• Cells hydrolyze storage polysaccharides into
sugars as needed.
• Two most common storage polysaccharides are
starch and glycogen
ALPHA & BETA
LINKAGES
• ALPHA & BETA LINKAGES HAVE TO
DO WITH WHERE THE HYDROXYL
GROUP (-OH) IS ATTACHED TO THE #1
CARBON
• ALPHA (a) = below the plane
• BETA (b) = above the plane
a & b LINKAGES
STARCH
• Glucose polymer that is a storage polysac. In
plants
• Helical glucose polymer with a 1-4 linkages
• Stored as granules within plant organelles called
plastids
• Amylose, the simplest form, unbranched polymer
• Amylopectin is branched polymer
• Most animals have digestive enzymes to
hydrolyze starch
• Major sources in human diet are potatos and
grains
POLYSACCHARIDES
GLYCOGEN
• Glucose polymer that is a storage polysac.
In animals
• Large glucose polymer that is more highly
branched than amylopectin
• Stored in the muscle and liver of humans
and other vertebrates
GLYCOGEN
STRUCTURAL
POLYSACCHARIDES
• INCLUDE CELLULOSE AND CHITIN
• CELLULOSE- a major structural component of
plant cell walls
– Differs in starch in its glycosidic linkages
– CELLULOSE FIBRILS FORMED BY HYDROGEN
BONDING BETWEEN HYDROXYL GROUPS OF
PARALLEL MOLECULES(PAGE 64)
– Cannot be digested by most organisms, because they
lack an enzyme that can hydrolyze the b 1-4 linkage;
grazing animals are an exception to this
STRUCTURAL
POLYSACCHARIDES
• CHITIN- a polymer of an amino sugar
• Forms exoskeletons of arthropods
• Found as a building material in the cell
walls of some fungi
• Monomer is an amino sugar, which is
similar to b glucose with a nitrogen
containing group replacing the hydroxyl on
carbon 2.
CHITIN IN EXOSKELTONS
• WHICH OF THESE ANIMALS HAVE
EXOSKELETONS?
STARCH AND CELLULOSE
• STARCH- glucose monomers are in a configuration (-OH
group on carbon is below the ring’s plane)
• CELLULOSE- glucose monomers are in b configuration
(-OH group on carbon one is above the ring’s plane)
LIPIDS
• BUTTER: GOOD OR BAD???
LIPIDS: DIVERSE
HYDROPHOBIC MOLECULES
Lipids are a diverse group of organic compounds
That are insoluble in water, but will dissolve in
Nonpolar solvent (e.g. ether, chloroform,benzene),
Important groups are fats, phospholipids, and
Steroids.
FATS STORE LARGE
AMOUNTS OF ENERGY
• FATS = Macromolecules constructed from
– 1) GLYCEROL- a 3-carbon alcohol
– 2) FATTY ACID- (carboxylic acid)
• Made of a carboxyl group at one end and an attached
hydrocarbon chain (tail)
• Carboxyl functional group (head) has properties of an acid
• Hydrocarbon chain has a long carbon skeleton usually with an
even number of carbon atoms (16-18)
• Nonpolar C-H bonds make the chain hydrophobic and not
water soluble
FORMATION OF FATS
•
DURING THE FORMATION OF A FAT, ENZYMECATALYZED CONDENSATION REACTIONS LINK
GLYCEROL TO FATTY ACIDS BY AN ESTER
LINKAGE, a bond between a hydroxyl group and a
carboxyl group
SOME CHARACTERISTICS
OF FAT
• Fats are insoluble in water. The long fatty acid
chains are hydrophobic because of the many
nonpolar C-H bonds
• The source of variation among fat molecules is the
fatty acid composition
• Fatty acids in a fat may all be the same, or some
(or all) may differ
• Fatty acids may vary in length
• Fatty acids may vary in the number and location
of carbon-to-carbon double bonds
SATURATED V.
UNSATURATED FATS
• SATURATED
• No double bonds btw.
carbons in fatty acid tail
• Carbon skeleton of fatty
acid is bonded to
maximum number of
hydrogens (saturated
with hydrogens)
• Usually solid at room
temp
• Most animal fats
• UNSATURATED
• One or more double bonds
between carbons in fatty
acid tail
• Tail kinks at each C=C, so
molecules do not pack
closely enough to solidfy
at room temp
• Usually liquid at room
temp
• Most plant fats
SATURATED AND
UNSATURATED FAT
MOLECULES
WHICH IS SATURATED??? HINT: NO DOUBLE BONDS
IN TAIL
FATS SERVE USEFUL
FUNCTIONS
• ENERGY STORAGE- one gram of fat
stored twice as much energy as carb or
protein
• CUSHIONS VITAL ORGANS IN
MAMMALS
• INSULATES AGAINST HEAT LOSS
PHOSPHOLIPIDS
• COMPOUNDS WITH MOLECULEAR BUILDING
BLOCKS OF GLYCEROL, TWO FATTY ACIDS, A
PHOSPHATE GROUP, AND USUALLY AND
ADDITIONAL SMALL CHEMICAL GROUP
ATTACHED TO THE PHOSPHATE
PHOSPHOLIPID INFO.
• Differ in fat in that the third carbon of glycerol is
joined to a negatively charged phosphate
• Can have small variable molecules attached to the
phosphate
• Show ambivalent behavior toward water.
Hydrocarbon tails are hydrophobic and the polar
head is hydrophilic
• Cluster in water as their hydrophobic portions turn
away from water
• Are major constituents of cell membranes.
PHOSPHOLIPID BILAYER
• AT THE CELL SURFACE, PHOSPHOLIPIDS
FROM A BILAYER HELD TOGETHER BY
HYDROPHOBIC INTERACTIONS AMONG
THE HYDROCARBON TAILS.
STERIODS
• LIPIDS which have four fused carbon rings with various
functional groups
• CHOLESTEROL IS AN IMPORTANT STERIOD
– Is the precursor to many other steroids including vertebrate sex
hormones and bile acids
– Is the common component of animal cell membranes
CHOLESTEROL
PROTEINS
• POLYPEPTIDE CHAINS- polymers of amino
acids that are arranged in a specific sequence and
are linked by peptide bonds
• PROTEIN-Consists of one or more polypeptide
chains folded and coiled into specific
conformations
– Are abundant, making up 50% or more of cellular dry
weight
– Vary extensively in structure
– Are made up of only 20 different amino acids (mostly)
– Have important and varied functions in the cell
PROTEIN STRUCTURE
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FUNCTIONS OF PROTEINS
•
•
•
•
•
•
•
STRUCTURAL SUPPORT
STORAGE OF AMINO ACIDS
TRANSPORT (E.G. HEMOGLOBIN)
SIGNALING ( CHEMICAL MESSENGERS)
MOVEMENT (CONTRACTILE PROTEINS)
DEFENSE (ANTIBODIES)
CATALYSIS OF REACTIONS (ENZYMES)
POLYPEPTIDES
• CHAINS OF AMINO ACIDS
• CONSIST OF A CARBON, BONDED TO
–
–
–
–
1) HYDROGEN ATOM
2) CARBOXYL GROUP
3) AMINO GROUP
4) VARIABLE R GROUP (SIDE CHAIN) SPECIFIC TO EACH
AMINO ACID
PEPTIDE BOND
• COVALENT BOND FORMED BY A
CONDENSATION REACTION THAT LINKS
CARBOXYL GROUP OF ONE AMINO ACID
TO THE AMINO GROUP OF ANOTHER
POLYPEPTIDE CHAINS RANGE IN LENGTH FROM
A FEW AMINO ACIDS TO MORE THAN A THOUSAND
PROTEIN SHAPES
• A PROTEIN’S FUNCTION DEPENDS
UPON ITS UNIQUE CONFORMATION
• PROTEIN CONFORMATION-3-D
SHAPE OF A PROTEIN
• NATIVE CONFORMATIONFUNCTIONAL CONFORMATION OF A
PROTEIN FOUND UNDER NORMAL
BIOLOGICL CONDITIONS
FOUR LEVELS OF PROTEIN
STRUCTURE
• PRIMARY STRUCTURE– A UNIQUE SEQUENCE OF AMINO ACIDS
– DETERMINE BY GENS
– SLIGHT CHANGE CAN AFFECT A
PROTEIN’S CONFORMATION AND
FUNCTION (E.G. SICKLE CELL
HEMOGLOBIN)
PRIMARY STRUCTURE
PRIMARY STRUCTURE
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SECONDARY STRUCTURE
• REGULAR, REPEATED COILING AND
FOLDING OF A PROTEIN’S POLYPEPTIDE
BACKBONE
• STABILIZED BY H+ BONDS BTW. PEPTIDE
LINKAGES IN THE BACKBONE
• THE MAJOR TYPES OF SECONDARY
STRUCTURE ARE
– ALPHA HELIX AND BETA PLEATED SHEET
SECONDARY STRUCTURE
• ALPHA HELIX
BETA SHEETED
• FOUND IN FIBROUS PROTEINS (KERATIN AND
COLLAGEN)
• H+ BONDS HELP WITH STABILIZATION
SECONDARY STRUCTURE
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TERTIARY STRUCTURE
• THE 3-D SHAPE OF A PROTEIN
• THE IRREGULAR CONTORTIONS OF A
PROTEIN ARE DUE TO BONDING BTW. AND
AMONG SIDE CHAINS (R GROUPS) AND TO
INTERACTIONS BETWEEN R GROUPS AND
THE AQUEOUS ENVIRONMENT
• HYDROPHOBIC R GROUPS CLUMPS
TOWARDS INSIDE AND HYDROPHILIC R
GROUPS CLUMP TO THE OUTSIDE
TERTIARY STRUCTURE
• MANY ARE GLOBULAR PROTEINS
TERTIARY STRUCTURE
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QUARTERNARY STRUCTURE
• RESULTS FROM THE INTERACTIONS
BETWEEN AND AMON SEVERAL
POLYPEPTIDE CHIANS
– EX: COLLAGEN, A FIBROUS PROTEIN
FOUND IN ANIMAL CONNECTIVE
TISSUE, VERY STRONG DUE TO SHAPE
QUARTERNARY STRUCTURE
• MADE OF 2 OR MORE SEPARATE CHAINS,
HELD TOGETHER BY H+ BONDS,
INTERACTIONS AMONG R GROUPS, AND
DISULFIDE BONDS
QUARTERNARY STRUCTURE
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WHAT DETERMINES A
PROTEIN’S SHAPE?
• A PROTEIN’S 3-D SHAPE IS A CONSEQUENCE
OF THE INTERACTIONS RESPONSIBLE FOR
SECONDARY AND TERTIARY STRUCTURE
• THIS CONFORMATION IS INFLUENCED BY
PHYSICAL AND CHEMICAL
ENVIRONMENTAL CONDITONS
• IF A PROTEIN’S ENVIRONMENT IS ALTERED,
IT MAY BECOME DENATURED AND LOSE ITS
NATIVE CONFORMATION
DENATURATION
• PROTEINS CAN BE DENATURED BY:
– TRANSFER TO AN ORGANIC SOLVENT
– CHEMICAL AGENTS THAT DISRUPT H+ BONDS, IONIC
BONDS AND DISULFIDE BRIDGES
– EXCESSIVE HEAT
– ***SOME DENATURED PROTEINS WILL RETURN TO
THEIR NATIVE CONFORMATION WHEN CONDITIONS
RETURN TO NORMAL
NUCLEIC ACIDS:
INFORMATIONAL POLYMERS
• NUCLEIC ACIDS STORE AND TRANSMIT
HEREDITARY INFORMATION
• PROTEIN CONFORMATION IS DETERMINED
BY PRIMARY STRUCTURE. PRIMARY
STRUCTURE IN TURN, IS DETERMINED BY
GENES; HEREDITARY UNITS THAT
CONSIST OF DNA, A TYPE OF NUCLEIC
ACID.
• THERE ARE 2 TYPES OF NUCLEIC ACIDS
2 TYPES OF NUCLEIC ACIDS
• DNA
– CONTAINS CODED INFO THAT PROGRAMS ALL
CELL ACTIVITY
– CONTAINS DIRECTIONS FOR ITS OWN
REPLICATION
– IS COPIED AND PASSED FROM ONE
GENERATION OF CELLS TO ANOTHER
– IS FOUND IN THE NUCLEUS
– MAKES UP GENES THAT CONTAIN
INSTRUCTIONS FOR PROTEIN SYNTHESIS
• RNA
– FUNCTIONS IN THE ACTUAL SYNTHESIS OF
PROTEINS CODED FOR BY DNA
– SITES OF PROTEIN SYNTHESIS ARE ON
RIBOSOMES IN THE CYTOPLASM
– MESSENGER RNA (mRNA) CARRIES ENCODED
GENETIC MESSAGE FROM THE NUCLEUS TO
THE CYTOPLASM
– THE FLOW OF GENETIC INFO GOES FROM:
– DNA>>>RNA>>>PROTEINS
DNA TO PROTEINS
NUCEIC ACID STRAND: A
POLYMER OF NUCLEOTIDES
• NUCLEIC ACID- polymer of nucleotides
linked together by condensation reactions
• NUCLEOTIDE- building block molecule of
nucleic acid; made of
– 1) five carbon sugar covalently bonded to
– 2) phosphate group
– 3) a nitrogenous base
THE STRUCTURE OF
NUCLEOTIDES
NUCLEOTIDE WITH
ADENINE (BASE)
NITROGENOUS BASES
• THERE ARE 2 FAMILIES OF NITROGENOUS
BASES
– PYRIMIDINES: A SIX-MEMBERED RING MADE
OF CARBON AND NITROGEN
• CYTOSINE(C)
• THYMINE (T);FOUND ONLY IN DNA
• URACIL (U); FOUND ONLY IN RNA
-PURINES: A FIVE-MEMBERED FING FUSED TO A SIXMEMBERED RING
ADENINE(A)
GUANINE(G)
ATP- chemical energy nucleotide
• Adenine, 5-carbon sugar, 3 phosphate groups
DNA
• RESULTS FROM JOINING
NUCLEOTIDES TOGETHER
BY COVALENT BONDS CALLED
PHOSPHODIESTER LINKAGES.
THE BOND IS FORMED BETWEEN
THE PHOSPHATE OF ONE
NUCLEOTIDE AND THE SUGAR
OF THE NEXT