Karbohidratlar

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Carbohydrates a) Solar energy
Carbohydrates Other
organic compounds b) Definition Carbohydrates
contain carbon, hydrogen, and oxygen which can
directly, or indirectly after
hydrolysis, reduce alkali solutions of heavy
metal salts. They are generally known as
POLYHYDROXYALDEHYDES or KETONES and can
yield aldehydes or ketones upon
hydrolysis. Carbohydrate hydrated carbons.
The general formula is Cm(H2O)n c) Types 1)
MONOSACCHARIDES 2C 9C the simplest of
carbohydrates in that they cannot yield smaller
molecules upon hydrolysis 2)
OLIGOSACCHARIDES 2 10 monosaccharides units
joined by GLYCOSIDIC LINK
oligosaccharides, upon hydrolysis, will yield
constituent monosaccharides 3) POLYSACCHARIDES
gt 10 monosaccharide units joined by glycosidic
links oligosaccharides, upon hydrolysis,
will yield constituent monosaccharides 4)
HOMOPOLYSACCHARIDES contain the same
monosaccharide units 5) HETEROPOLYSACCHARIDES
contain different monosaccharide units
photosynthesis
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Carbohydrates d) BIOCHEMICAL IMPORTANCE 1)
Energy provision and storage 2) Structure and
protection 3) Conversion to other compounds
eg. Carbohydrates Fat 4)
Internal units of other compounds eg. Ribose in
RNA NAD etc. Monosaccharides
ALDOSES Contain Aldehyde groupings (
ose sugar ) KETOSES Contain Ketone groupings
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Carbohydrates
TRIOSES D-glyceraldehyde (OH on right hand
side) D- SERIES SUGARS predominent sugars in
nature are in the D- series L- series sugars
can not be used
KETOSES
ALDOSES
(1)
(2)

n - 1
simplest
A sugar with 3 carbon atoms is known as TRIOSE
(aldehyde, ketone) TETROSES
Aldose form D- ERYTHROSE Aldose sugar in D series
Ketose form D- ERYTHROLOSE Ketone sugar in
D-series



only one chiral center
chiral center
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Carbohydrates PENTOSES (5 C) ALDOSES 4 D-SERIES
MEMBERS KETOSES 2 D- SERIES MEMBERS HEXOSES (6
C) ALDOSES 8 D- SERIES MEMBERS KETOSES 4 D-SERIES
MEMBERS RING STRUCTURES (cyclic form)
- carbon chain tends to bend back upon
itself - O and -OH brought together to
favour HEMIACETAL FORMATION

chiral center
PYRANE
PYRANOSE
HEMIACETAL Hemiacetal is a condensation of
aldehyde and hydroxy (-OH) groups.
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HEMIACETAL FORMATION PYRANOSE contains 5
carbons and 1 oxygen. Aldose form The
oxygen is placed between the carbons at the
position C1 and C5. Ketose form The
oxygen is placed between the carbons at the
position C2 and C6. FURANOSE
contains 4 carbons and 1 oxygen. Aldose form
The oxygen is placed between the carbons at the
position C1 and C4. Ketose form The oxygen is
placed between the carbons at the position C2 and
C5.
1
1
2
3
2
1
2
3
1
4
3
2
4
5
3
4
4
5
6
5
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HEMIACETAL FORMATION
As a consequence of ring structure we have a
chiral center. If OH is projecting downwards
a anomer If OH is
projecting upwards
ß anomer f) REACTIVITY 1)
Potential reducing group an
unreacted OH group at C1 of aldose and C2 of
ketose an unreacted OH group is a potential
reducing group, forming a straight-chain
molecule with an aldehyde grouping on the end
b
a
a
b
aldehyde grouping
straight chain form
b anomer
a anomer
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HEMIACETAL FORMATION 2) High capacity to rotate
plane polarized light (POLARIMETER) - Translated
in to sugar units. 3) Separation by
CHROMATOGRAPHY - HPLC - Gas chromatography (use
of derivatives) 4) High capacity to interact
with water - Hydrophilic Naturally Occurring
Monosaccharides TRIOSES D-GLYCERALDEHYDE-3-PHOS
PHATE DIHYDROXYACETONE PHOSPHATE
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PENTOSES
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HEXOSES
D-MANOSE is a naturally occuring aldose. The
combined form is Polysaccharides
Mucopolysaccharides
D-GLUCOPYRANOSE is the most abundant monosaccharid
e in nature. We can find the free form in animal
blood. It feeds the brain and is found in plant
sap. The combined form is Oligosaccharides
Polysaccharides.
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a anomer
Combined form in Oligosaccharides and
Polysaccharides.
In free form it occurs as Pyranose, but
in combined form it occurs as Furanose. In the
a-anomer, the OH hangs down (involved in cyclic
form of sugar).
Ring structures have to involve aldehyde or
ketone groupings.
Fructose in free form is sweet component of
foetal animal blood component of
photosynthetic plant sap present in seminal
fluid (provides energy for sperm) basic
building blocks of oligo and polysaccharides
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MONOSACCHARIDES DERIVATIVES modification of
structure 1) AMINO SUGARS
Frequently NH2 (basic) occurs as
(neutral)
(N acetyl grouping). This removes the basicity
of NH2 .
D- GALACTOSAMINE D- MANNOSAMINE these amino
sugars give us MUCOPOLYSACCHARIDES (components
by definition) associated with structure and
protection of cells they are also occasionally
acylated
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MONOSACCHARIDES DERIVATIVES 2) SUGAR ACIDS
COH
COH
COOH
o
o
readily oxidized
readily oxidized
COOH
CH2OH
CH2OH
URONIC ACID FAMILY
ALDONIC ACID FAMILY
D-GLUCURONIC ACID D-GALACTURONIC
ACID D-MANNURONIC ACID
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MONOSACCHARIDES Detoxication Detoxication makes
sugar acids more water soluble so they can be
excreted (eg. ASPIRIN derivative of D-glucuronic
acid). In combined form, these turn up in various
polysaccharides. Can vary the behaviour of
carbohydrates by potential basic group (negative
group) on uronic acid. Monosaccharides are
joined via glycosidic link. OLIGOSACCHARIDES
a and b exist in equilibrium if
starting off with the b form ? METHYL-b-D-GLUCOSID
E there would be a potential for two entirely
different compounds
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OLIGOSACCHARIDES
1) a-GLUCOSIDE is easily hydrolyzed
succeptible to attack by a-GLUCOSIDASE enzyme
2) b-GLUCOSIDE is less easily hydrolyzed
also attacked by b-GLUCOSIDASE enzyme
a-GLYCOSIDIC LINKS polysaccharides involved in
energy production is easily hydrolyzed and can
be attacked by an enzyme b-GLYCOSIDIC LINKS
is extremly hard to hydrolyze and very stable
has biological importance in structure and
protective compounds OH group can be provided
by another sugar (naturally occurring
disaccharides)
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NATURALLY OCCURING DISACCHARIDES
1)
Maltose a naturally occuring disaccharide a
degradation product of starch easily hydrolyzed
Maltose is the same as Methanol except that it
uses OH on the second sugar group. As soon as
this occurs the ring structure cannot be opened.
2)
Cellobiose a degradation product of cellulose
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3)
Lactose
Lactose is a milk sugar (5 composition of milk).
It provides energy for infants. Lactose
intolerance is the lack of enzyme that helps to
digest lactose.
no unreacted OH grouping locked tight
shut no potential reducing group
NON-REDUCING SUGAR it does not have the
capacity to reduce heavy metals or salts
4)
Sucrose sweetener plant product commercial
- sugar cane - sugar beet
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5) TREHALOSE a non reducing sugar
in insects contains 2 glucose
molecules POLYSACCHARIDES GENERAL a) most
abundant type of carbohydrate b) classification
1) ENERGY - a-glycosidic link 2)
STRUCTURE AND PROTECTION - b-glycosidic
link ENERGY POLYSACCHARIDES GENERAL - why are
these used by the cell? 1) Large molecular
weight - large mass 1) large aggregates of
small MW compounds vrs. 2) colloid state found
with larger molecules 2) Protection of cells
colligative properties - the properties of
solution are dependent upon the particles -
larger molecules are easier to store (carry
around) and also protect against water
loss - water balance - osmotic properties of a
cell depend upon the number of particles in
solution and not the mass of those particles - 1
gram of polysaccharide has the same osmotic
properties as a milligram of individual
glucose units
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POLYSACCHARIDES 3) PLANT STARCH a) Occurs as
granules in cell cytoplasm (30 - 100 nm
chains). b) They are heterogenous (molecular
similarity). Plant starch is composed of 1
part AMYLOSE and 3 parts AMYLOPECTINE. c) Plant
starch composes 60 of our daily caloric
intake. AMYLOSE composed of D- glucose units
joined in 1-4 a glycosidic links polymers
of maltose molecular weight is 60,000 to
1,500,000 daltons AMYLOPECTINE structure is
not linear branched (tree-like) with chains
of D-glucose units joined in a 1-4
a-glycosidic link branch points of 1-6
a-glycosidic link (anomeric C atom (aldose
and ketose C)) - always involves C1
branching provided by OH on C6 25 units per
chain compacts the space taken by many
glucose units into a smaller volume
25 units
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POLYSACCHARIDES 4) GLYCOGEN animal product
and is present in muscle and liver muscle is a
primative sort of tissue with primative energy
derivation it has very large molecular weight
(millions) it's structure is similar to
amylopectine except that it is more highly
branched the molecules in glycogen are more
compact and it has 1 to 6 a-glycosidic
links every 8 to 10 units is a D-glycose
unit 5) DEXTRANS form of energy storage in
bacteria it is composed of D-glucose joined
via various glycosidic links STRUCTURAL
POLYSACCHARIDES CELLULOSE the most abundant
natural product and 50 of all natural organic
material in biosphere contain cellulose has
linear chains of D-GLUCOSE units joined via 1-4
b-glycosidic links the polymer of
CELLOBIOSE has the same chemical component of
amylose and is involved in structure and
rigidity of plant cells (H-bonding between
chains) not utilized by mammals except the
ruminants (ruminants possess symbiotic
microorganisms in lumen) cellulose provides an
easy and cheap way to feed cattle
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MUCOPOLYSACCHARIDES a) Generally occur in
association with proteins GLYCOPROTEINS lt 4
hexosamine (amino sugars) MUCOPROTEINS gt 4
hexosamine b) Chitin (no protein)
N-ACETYL-D-GLUCOSAMINE units joined via1-4
b-glycosidic link compare to structure of
cellulose exoskeletons of insects and
crustaceans important in pesticide
development c) Mucopolysaccharides have a wide
range of activities Hyaluronic acid,
D-Glucuronic acid, N-Acetyl-D-Glucosamine
joined by 1,3 b- and 1,4 b-glycosidic links
found in cell coat joint lubricants blood
group factors and blood typing reflects in
surface of red blood cell an anticoagulant
(heparine) is a mucopolysaccharide
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POLYSACCHARIDE DEGRADATION General a)
polysaccharides undergoes degradation to permit
use of constituent monosaccharides (plant
starch, glycogen) b) Pathway of degradation
varies with cellular location. Release of
monosaccharides 1) Extracellular (outside of the
cell) hydrolysis eg. D-GLUCOSE
gastrointestinal tract - still considered outside
of the body - cells secrete enzymes to
outer body that conduct
hydrolysis salivary amylase and pancreatic
amylase - catalyze the hydrolysis of 1-4
a-glycosidic links - amylo-1,6-a-glucosidase -
hydrolysis of any branch
points (1-6 a) - introduction
of water - important to digestion (broken down
before being absorbed)
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Release of monosaccharides 2) Intracellular
phosphorolysis - bond cleavage with phosphoric
acid (uses elements of phosphate) -
working from non-reducing end of molecule -
nucleophilic attack of phosphate on C1 - chopping
off at non reducing end (branching points are
obstacles) - phosphorilytic degradation of
glycogen results in release of D-glucose-1-phospha
te - controlled by consumption of the product -
enzyme ? phosphorylase regulated and this system
is crutial in deriving energies from energy
bank - 2 forms of phosphorylases a and b -
bond breaking, covalent modification
balance
Phosphorylase b (inactive)
Phosphorylase a (active)
2 Pi
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Phosphorylase phosphatase conversion between
active and inactive forms inactive form is in
muscle if using phosphate group from ATP ? ADP
and AMP accumulate (trouble) AMP positively
modifies system (changes shape of the phosphatase
to make it active) take AMP and use it as an
allosteric modifier to convert to an active
form ATP (negative) and AMP (positive) compete
for allosteric sites What turns
phosphorylase kinase on? hormones ADRENALIN in
muscle, GLUCAGON in liver stimulate the release
ATP upon hormone stimulation releases 2
pyrophosphate cAMP stimulates the enzyme system
and turns the protein kinase inactive to a
protein kinase active. The active protein
kinase stimulates the phosphorylase kinase.
release of glucose from glycogens creates instant
release of energy
always operational
2 Pi
() AMP
(-) ATP
Phosphorylase a active
Phosphorylase b inactive
Phosphorylase phosphatase
allosteric modification
covalent modification
Phosphorylase kinase
phosphotase cleaves off Pi
2 ATP
2 ADP
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Phosphorylase phosphatase cAMP intracel
lular messenger ATP AMP PP (
pyrophosphate) Protein Kinase
(inactive) Protein Kinase (active) adenylate
cyclase cAMP Phosphorylase Kinase cAMP
stimulates the enzyme system and turns the
protein kinase inactive to a protein kinase
active the active protein kinase stimulates the
phosphorylase kinase How does the system know
when to shut down? - by consuming cAMP
upon hormonal stimulation
covalent modification
stimulates
forms
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