2. ⦿Polyhydroxy aldehydes or ketones or
substances that yield such compunds on
hydrolysis.
⦿Empirical formula: (CH2O)n
⦿Some carbohydrates may contain nitrogen,
phosphorous or sulphur.
3. ⦿Monosaccharides:
◼glucose, fructose and galactose in fruits and
honey & obtained by hydrolysis of oligo- &
polysacs.
⦿Disaccharides:
◼sucrose, lactose, maltose (by hydrolysis of
starch).
⦿Polysaccharides:
◼starch (in potatoes, rice, corn and wheat)
◼Cellulose (in cell wall of plants) not digested by
humans due to absence of cellulase
5. ⦿Simplest carbohydrates.
⦿Cannot be hydrolysed into smaller carbohydrates.
⦿They are either aldehydes or ketones with two or
more hydroxyl groups.
⦿All carbon atoms are linked by single bonds.
⦿If carbonyl group is attached at the end of carbon
chain monosaccharide is an “aldose”.
⦿If carbonyl group is at any other position then it is
“ketose”.
8. ⦿Reducing nature: due to pressure of free
aldehyde and ketone group. It reduces Cu²+
to Cu+ and thus called reducing sugars.
⦿This property is basis for Benedict’s test and
Fehling’s test for detection of glucose level in
urine and blood in diagnosis of Diabetes
mellitus.
⦿Aldehyde and ketone group can join an
alcoholic group of another organic compound
and forms new compound linkage called as
“glycosidic bond”.
9. ⦿Have a chiral center. Carbon having four
different substituents attached to it. E.g.
glyceraldehyde. When hydroxyl group on the
reference carbon is on right, then the sugar is
D-isomer and when on left, it is L-isomer.
⦿In aqueous solution monosachharides with
five or more carbon atoms in the backbone
occurs as cyclic ring structures.
10. ⦿ Trioses are intermediates in photosynthesis.
⦿ Glucose is the main fuel in all cells and is an
instant source of energy.
⦿ Monosachharides such as ribose are components
of macromolecules.
⦿ Acts as building block of the formation of
disachharides and polysachharides.
⦿ Glucose is also used in the formation of fats and
amino acids
11. ⦿Formed by joining together 2-6
monosachharide molecules.
⦿Units are joined by glycosidic bond which is
formed when hydroxyl group of one sugar
reacts with anomeric carbon of the other.
13. ⦿Called as double sugars
⦿Biologically important disaccharides are:
Maltose, sucrose and lactose.
⦿Maltose is also called “Malt sugar” is
composed of two glucose molecules.
⦿Sucrose is commonly known as “Cane sugar”.
Glucose and fructose form sucrose. It is a
non-reducing sugar.
⦿Lactose also called as “milk sugar”.
Composed of glucose and galactose.
14.
15. ⦿Sweetish to taste
⦿Dissolves in water to form true solution
⦿Hydrolyse into free monosaccharide units
when treated with dilute acid.
⦿Maltose and lactose are reducing sugars and
sucrose is not.
16. ⦿Serves as energy source.
⦿Act as reserve food material e.g. sucrose in
sugarcane and sugarbeet.
⦿Oligosaccharides attach to cell membrane and
help in recognizing cells of their own kind.
17. ⦿Consists of more than six molecules of
monosachharides joined by glycosidic linkage.
⦿They may be linear branched or unbranched
chains.
⦿Types: homopolysaccharides and
heteropolysaccharides.
⦿Important biological polysaccharides are:
◼Starch : strorage polysaccharide in plants
◼Glycogen: storage polysachh in animals
◼Cellulose : structural polysacch.
19. ⦿Starch and glycogen act as reserve food
material for plants and animals.
⦿Serves as energy source
⦿Chitin provides protection and support.
⦿Heparin prevents clotting of blood in blood
vessels.
20. Glucose has three major fates:-
⦿Stored as polysaccharide
⦿Oxidized to three carbon compound
(glycolysis and kreb’s cycle)
⦿Uptake by other tissues (by faciltated
diffusion)
21. ⦿Formation of glycogen from glucose.
⦿Takes place in liver and muscle cells.
⦿Consists of 5 steps:
⦿Phosphorylation
⦿Rearrangemment
⦿Dephosphorylation
⦿Condensation
⦿Branching
22. ⦿Phosphorylation: glucose is phosphorylated
to glucose-6-phosphate by glucokinase with
the help of ATP.
⦿Rearrangement: glucose -6 phosphate
rearranges to glucose-1- phosphate with help
of phosphoglucomutase and cofactor Mg2+.
⦿Dephosphorylation: glucose-1-phosphate
then reacts with uridine triphosphate (UTP)
and forms uridine diphosphate glucose
complex (UDGP) and PPi. This reaction is
catalysed by UDPG pyrophosphorylase.
23. ⦿Condensation: glucose UDPG is transferred to
a to a preformed glycogen molecule through
glucogen synthetase with release of UDP.
Leads to formation of glycogen molecule
longer by one glucose unit.
⦿Branching: when glycogen molecule becomes
6-11 glucose units long, a branching enzyme
leaves fragments from one chain and
transfers them to 1,6 linkage in another
thereby starting a branching point in glycogen
molecule. Synthetase then lengthens branch
by adding glucose units until desired length is
reached.
24.
25. ⦿ Breakdown of glycogen to release glucose units so
that it can enter glycolytic cycle and energy can
be derived from it.
⦿ Occurs in liver when blood glucose level falls
below normal.
⦿ Has four steps:
⦿ Phosphorylation
⦿ Debranching
⦿ Rearrangement
⦿ Dephosphorylation
26. ⦿Phosphorylation: glycogen phosphorylase in
presence of inorganic phosphorous breaks 1-4
glycosidic bond in glycogen molecule and
removes glucose unit as glucose-1-phosphate.
⦿Debranching: debranching enzyme known as
oligo-α (1-6) to α (1-4) glycantransferase
hydrolytically split the glucose molecule from
1,6- linkage and liberates free glucose.
⦿
27. ⦿Rearrangement: Glucose-1-phosphate
released in 1st step is converted to glucose-6-
phosphate by phosphoglucomutase in
presence of magnesium ion.
⦿Dephosphorylation: glucose-6-phosphate is
then converted to glucose by glucose-6-
phosphatase with release of phosphate group.
⦿Note: glycogenolysis is stimulated by
hormones epinephrine and glucagons.
28.
29. ⦿Splitting of sugar.
⦿Molecule of glucose is degraded in series of
enzyme-catalysed reactions to yield two
molecules of three carbon compound-
pyruvate.
⦿Takes place in cytoplasm of the cells. It is
said to be aerobic because it uses oxygen.
⦿Anaerobic phase includes conversion of
glucose to lactate.
30. ⦿Phosphorylation: Glucose is activated for
subsequent reactions by its phosphorylation
at C-6 to yield glucose-6-phosphate with ATP
as donor of phosphoryl group. Reaction is
catalyzed by hexokinase in presence of Mg
ion.
⦿Isomerization: glucose-6-phosphate is
isomerized to fructose-6-phosphate by
phosphoglucoisomerase.
31. ⦿Phosphorylation: phosphofructokinase-1
catalyses the transfer of a phosphoryl group
from ATP to fructose-6-phosphate to yield
fructose 1,6-biphosphate.
⦿Splitting: fructose 1,6 biphosphate now splits
into two different triose phospate,
glyceraldehyde 3-phosphate and
dihydroxyacetone phosphate.
32. ⦿Phosphorylation and dehydrogenation:
glyceraldehyde 3- phosphate is phosphorylated
in presence of inorganic phosphate and is
dehydrogenated to 1,3- biphosphoglycerate by
gylceraldehyde 3- phosphate dehydrogenase.
NAD+ acts asa hydrogen acceptor.
⦿Dephosphorylation: Phosphoglycerate kinase
transfers high energy phosphoryl group from
1,3 biphosphoglycerate to ADP forming ATP and
3-phosphoglycerate.
33. ⦿Isomerization: 3-phosphoglycerate is
converted to its isomer 2-phosphoglycerate
by phosphoglycerate mutase in presence og
Mg2+.
⦿Dehydration: 2-phosphoglycerate then loses
water in presence of enzyme enolase and
changes to phosphoenol pyruvate.
⦿Dephosphorylation: phosphoryl group from
phosphoenol pyruvate to ADP catalyzed by
pyruvate kinase which requires Mg2+
34.
35. ⦿In glycolysis net gain is 2ATP molecules, 2
pyruvate and 2NADH2 molecules.
⦿NADH2 when enters into electron transport
chain leads to production of 3ATP.
⦿Total ATP production is thus 8ATP per glucose
molecule.
36. ⦿If sufficient oxygen is available, each 3-
carbon pyruvate molecule enters
mitochondrial matrix where it is completely
oxidized.
⦿Carboxyl group is removed from pyruvate as a
molecule of CO2 and leaves behind 2-carbon
acetyl group. The reaction is catalysed by
enzyme pyruvate-dehydrogenase complex.
37.
38. ⦿Under aerobic conditions, Pyruvate is
oxidized to acetate which enters citric acid
cycle and is oxidized to CO2 and H2O. NADH
formed by dehydrogenation of glyceraldehyde
-3- phosphate is ultimately reoxidized to
NAD+ by passage of its electron to O2in
mitochondrial respiration.
⦿Under anaerobic conditions or hypoxic
conditions such as in very active skeletal
muscle, NADH generated cannot be oxidized
to O2.
40. ⦿ Condensation: condensation of acetyl CoA with
oxaloacetate to form citrate by citrate synthase
enzyme.
⦿ Dehydration: citrate undergoes rearrangement in
presence of aconitase forming cis-aconitate and
releases water molecule.
⦿ Hydration: water molecule adds to ci-aconitate
and converts into iso-citrate by enzyme
aconitase.
⦿ Oxidative decarboxylation: isocitrate is
decarboxylated to form α-ketoglutarate, in
presence of enzyme iso citrate dehydrogenase.
NADH2 is produced in this step.
41. ⦿Dehydrogenation and decarboxylation: α-
ketoglutarate is converted to succinyl~CoA
and CO2 by action of α-ketoglutarate
dehydrogenase. NAD+ is electron acceptor
and CoA act as carrier of succinyl group.
⦿Substrate level phosphorylation:
succinyl~CoA has thioster bond and energy
released by breakage of this bond is used to
drive synthesis of ATP. Succinyl~CoA
synthetase catalyses the reaction and
converts succinyl~CoA to succinate with
liberation of energy in form of GTP.
⦿
42. ⦿Dehydrogenation: process converts succinate
to fumarate by succinate dehydrogenase with
production of 1 FADH2.
⦿Hydration: molecule of water is added which
converts fumarate to malate. Reaction is
catalysed by fumarase.
⦿Dehydrogenation: malate dehydrogenase
catalyses the conversion of malate to
oxaloacetate and 1 NADH2 is produced.
43.
44. ⦿Glycolysis – 8ATP (gained 10ATP, Lost 2ATP)
⦿Oxidative decarboxylation- 3 X 2= 6ATP
⦿KREB’S cycle- 24ATP
⦿TOTAL GAIN: 38ATP.
45. ⦿Whole glucose is not synthesized by glycolysis
and citric acid cycle.
⦿Rest of the part is oxidized by Hexose
Monophosphate Shunt (HMP shunt)
⦿It occurs mainly in liver, adipose tissue,
lactating mammary glands, adrenal cortex,
gonads and erythrocytes.
47. ⦿ Glucose -6-phosphate is the starting point. It is
oxidized to 6-phosphoglucono lactone by NADP
linked glucose-6-phosphate dehydrogenase.
⦿ 1 molecule of NADPH2 is produced.
⦿ 6-phosphoglucono lactone is hydrolysed to 6-
phosphogluconic acid by lactonase.
⦿ 6-phosphogluconic acid is oxidised and
decarboxylated by NADP linked 6 phosphogluconic
acid dehydrogenase. Reaction need Mg2+ to form
ribulose-5-phosphate and liberates NADPH2.
48.
49. ⦿Ribulose-5-phosphate is converted to isomer
ribose-5- phosphate by phosphoriboisomerase
enzyme. While some gets converted to
xylulose-5-phosphate by epimerase.
⦿Ribose and xylulose-5-phosphate are acted
upon by transketolase which transfers keto
group from xylulose to ribose-5-phosphate. So
a seven carbon keto sugar –sedoheptulose-7-
phosphate and triose glyceraldehyde-3-
phosphate are formed.
50. ⦿Sedoheptulose -7-phosphate
⦿ and glyceraldehyde -3-phosphate are
converted into fructose -6-phosphate and
erythose-4-phosphate by transaldolase.
⦿Erythrose-4-phosphate and xylulose-5-
phosphate formed in step 1 of regenerative
phase react in presence of transketolase
forming fructose-6-phosphate and
glyceraldehyde-3-phosphate.
52. ⦿NADPH produced provides power for
biosynthetic reactions.
⦿Ribose-5-phosphate acts as a precursor for
nucleotide and nucleic acid synthesis.
⦿Fructose -6-phosphate and glyceraldehyde -3-
phosphate, may be metabolised in glycolysis
to produce energy.
53. ⦿Conversion of pyruvate and related
compounds like lactate, glycerol and amino
acids into glucose.
⦿Occurs during starvation and diabetes
mellitus.
⦿Takes place in liver and renal cortex.
54. ⦿Conversion of pyruvate to phosphoenol: it is
first coverted oxaloacetate by pyruvate
carboxylase with utilization of energy. Later
it gets converted to phosphoenol pyruvate.
Requires GTP for completion.
⦿Conversion of Fructose: 1,6- biphosphate to
fructose-6-phosphate: occurs with the help of
fructose-1,6- biphosphatase. Inorganic
phosphate is released in this reaction.
55. ⦿Conversion of glucose-6-phosphate to
glucose: in presence of glucose-6-
phosphatase by release of inorganic
phosphate.
⦿Gluconeogenesis requires 4ATP, 2GTP and
2NADH + 2H+ for production of glucose.
2pyruvate +4ATP+2GTP+2NADH+2H+ + 4H2O
Glucose+ 4ATP+ 2GDP+ 6Pi +2NAD+
56. ⦿A circuit in which lactate produced by
anaerobic glycolysis in skeletal system returns
to liver and converted to glucose moves back
to muscles to get converted into glycogen.
57. ⦿Extremely active muscles use glycogen stores
as energy source by generating lactate via
glycolysis.
⦿Lactate is transported to liver and is
converted to glucose via gluconeogenesis.
⦿Glucose is released in blood and returned to
muscles to replenish their glycogen stores.
⦿Overall pathway is called as cori cycle.
58. ⦿Blood glucose level- 60-100mg/100ml in
fasting.
⦿100-140mg/100ml following ingestion of
carbohydrate containing meal.
⦿Regulated by various hormones:
◼Insulin
◼Glucagon
◼Epinephrine
◼Glucocorticoids
59. ⦿Glucose enters the blood stream from
intestine after carbohydrate rich meal,
resulting in rise in blood glucose and
increased secretion of insulin.
⦿Insulin lowers the blood glucose level.
⦿It promotes glycolysis and speeds up the
uptake of glucose by tissues via glycogenesis.
⦿It suppresses glycogenolysis and
gluconeogenesis.
60. ⦿It is secreted by alpha cells of islets of
langerhans of the pancreas.
⦿Low blood glucose triggers the release of
glucagon which stimulates glucose release
from liver glycogen by promoting
glycogenolysis.
⦿Promotes gluconeogenesis and compensates
the low blood glucose level
61. ⦿Secreted by adrenal medulla
⦿Prepares body for increased activity by
mobilizing blood glucose from glycogen and
other precursors.
⦿Promotes glycogenolysis and gluconeogenesis
⦿Inhibits release of insulin
62. ⦿Secreted by adrenal cortex in response to low
blood glucose levels
⦿Stimulates gluconeogenesis from amino acids
and glycerol in liver, thus raising blood
glucose and counter balancing effects of
insulin.
63. ⦿Hyperglycemia
⦿Hypoglycemia
⦿Hyperglycemia: elevated blood glucose
levels. Caused by:
◼Overproduction of glucose
◼Under utilization of glucose.
◼Higher levels of glucose leads to more
loss of water in urine, as it contains
osmotically more active glucose
secretion. Leads to diabetes mellitus
64. ⦿A metabolic disorder occurring as a result of
deficiency of insulin characterized by
hyperglycemia and glycosuria.
⦿Two types:
◼Insulin- dependent DM
◼Non-insulin dependent DM
65. ⦿Occurs usually in childhood and younger age
group.
⦿Also called as juvenile-onset diabetes.
⦿Caused due to auto-immune destruction of
pancreatic beta cells. Fails to release insulin
hormone.
⦿Characterized by: hyperglycemia,
hyperlipoproteinemia, severe ketoacidosis.
66. ⦿Also called maturity onset diabetes.
⦿Occurs in middle age group especially in
obese.
⦿Adequate insulin is present, but fails to act
on target tissues.
⦿Decline in number of insulin receptors or
blocking interaction of insulin with its tissue
receptors is underlying cause.
67. ⦿It is the decrease in blood glucose level below
the fasting level (below 70mg/dL)
⦿At a level of 50mg/100 mL convulsions occur
⦿At a level of 30 mg/100 mL coma and death
result.
⦿-Hypoglycemia is more dangerous than
hyperglycemia because glucose is the only
fuel to the brain.
68. ⦿Causes:
i. Excess insulin:
a) Overdose of insulin.
b) Tumor of B-cells of pancreas (insulinoma).
ii. Hyposecretion of anti-insulin hormones:
(hypo-functions of the pituitary gland,
adrenals & thyroid gland). insulin acts
unopposed causing lowering of blood glucose
iii. Liver disease:
hypoglycemia is due to decreased glycogen
stores and
69. ⦿A glucose tolerance test measures how well
body is able to break down glucose, or sugar.
⦿Those who suffer from diabetes (type 1) have
trouble processing glucose because the body
is not able to make an adequate supply of
insulin.
⦿This test is also used to diagnose the
presence of gestational diabetes and type 2
diabetes.
71. ⦿ Patient is asked to give a blood sample, which is a
fasting blood sample.
⦿ Patient is asked to drink an extremely sweet and
concentrated solution of glucose within a given
amount of time (usually five minutes).
⦿ After this, patient is asked to wait until glucose levels
are tested again.
⦿ If patient is given 50-gram, or one-hour test, blood
sample will be taken after one hour.
⦿ If patient is given 75-gram, or two-hour test, blood
sample will be taken after every hour for two hours.
⦿ By taking several samples of blood, healthcare
provider will be able to tell how quickly body can
process glucose.
72. ⦿Normal glucose levels are:
⦿50-gram (one-hour test): equal or less than
140 mg/dL
⦿75-gram (two-hour test): fasting levels 60-100
mg/dL ; one-hour levels less than 200 mg/dL;
two-hours less than 140 mg/dL
73. ⦿Mitochondrial oxidation and oxidative
phosphorylation is the culmination of energy
yielding metabolism.
⦿During oxidation respiratory substrates,
reduced coenzymes like: FADH2, NADH2 and
NADPH2 are produced.
⦿These transfer protons and electrons by series
of reactions to O2 and get oxidized.
⦿This takes place in mitochondria and so called
as mitochondrial oxidation.
74. ⦿It consists of electron transfer chain which
ultimately results in ATP generation through
coupled process called oxidative
phosphorylation.
75. ⦿Consists of four electron carriers which are
large enzyme complexes capable of
catalyzing electron transfer.
⦿Four complexes are:
◼Complex I: NADH dehydrogenase complex
◼Complex II: Succinate dehydrogenase complex
◼Complex III: cytochrome C oxidoreductase.
◼Complex IV: cytochrome oxidase.
76. ⦿Energy obtained through the transfer of
electrons down the ETC is used to pump
protons from the mitochondrial matrix into
the intermembrane space, creating an
electrochemical proton gradient across the
inner mitochondrial membrane.
⦿This electrochemical proton gradient allows
ATP synthase (ATP-ase) to use the flow of
H+ through the enzyme back into the matrix
to generate ATP from adenosine
diphosphate (ADP) and inorganic phosphate.
77. ⦿Complex I (NADH coenzyme Q reductase;
labeled I) accepts electrons from the Krebs
cycle electron carrier nicotinamide adenine
dinucleotide (NADH), and passes them to
coenzyme Q (ubiquinone; labeled Q), which
also receives electrons from complex II
(succinate dehydrogenase; labeled II). Q
passes electrons to complex III (cytochrome
bc complex; labeled III), which passes them
to cytochrome c (cyt c). Cyt c passes
electrons to Complex IV
(cytochrome c oxidase; labeled IV), which
uses the electrons and hydrogen ions to
reduce molecular oxygen to water.
78.
79.
80. ⦿It catalyzes transfer of a hydride ion from
NADH to FMN, from which 2 electrons pass
through series of Fe-S centers.
⦿Electron transfer drives expulsion of 4 protons
(H+) from matrix.
81. ⦿Simpler and smaller than complex I.
⦿Complex transfers electrons from succinate to
FAD and then to Fe-S center.
⦿Finally transfering to ubiq-uinone and
reducing it to ubiquinol.
82. ⦿Transfers electrons from ubiquinol to cyt b
and then to Fe-S center.
⦿ finally to Cyt C. accompanied by flow of
four protons from matrix to intermembrane
space.
83. ⦿It carries electrons from cytochrome c to
molecular oxygen, reducing it to H2O.
⦿For every four electron passing through this
complex, the enzyme consumes four
substrate H+ from the matrix in converting O2
to H2O.
84. ⦿Overall transfer of two electrons from NADH
to O2 is accompanied with pumping of 10H+
from the matrix to inter-membrane space.
⦿It creates proton gradient.
⦿Higher concentration of proton concentration
in the inter-membrane space causes the
protons to pass inwardly into matrix through
inner membrane.
85. ⦿Inner membrane possess F◦ - F1 particles.
⦿ When proton flow through these particles, it
induces them to function as ATP synthetase and
proton motive force generated by proton gradient
then synthesizes ATP from ADP and Pi.
⦿ This process is called oxidative phosphorylation.
86. ⦿ In the mouth:
◼ Salivary amylase hydrolyzes starch into dextrin +maltose
⦿ In the stomach:
◼ due to drop of pH salivary amylase acts for a very short time
⦿ In the small intestines:
◼ Pancreatic and intestinal enzymes hydrolyze the oligo- and polysaccharides as
follows:
Pancreatic amylase
⦿ Starch maltose + isomaltose
Maltase
⦿ Maltose 2 glucose
Lactase
⦿ Lactose glucose + galactose
Sucrase
⦿ Sucrose glucose + fructose
87. ⦿ Simple diffusion:
◼ Depending on the concn gradient of sugars between
intestinal lumen and mucosal cells. e.g. Fructose and
pentose
⦿ Facilitated transport:
◼ It requires a transporter. e.g. Glucose, Fructose and
galactose
⦿ Active transport (co-transport):
◼ It needs energy derived from the hydrolysis of ATP.
glucose & galactose are actively transported against
their concentration gradients by this mechanism.
88. Anabolic in response to hyperglycemia
⦿Liver
◼Stimulates glycogen synthesis, glycolysis, and
fatty acid synthesis
⦿Muscle
◼Stimulates glycogen synthesis
⦿Adipose
◼Stimulates lipoprotein lipase resulting in uptake
of fatty acids from chylomicrons and VLDL
◼Stimulates glycolysis for glycerol phosphate
synthesis (precurser to triglycerides)
89. ⦿Catabolic, in response to hypoglycemia
⦿Liver
◼Activates glycogen degradation, gluconeogenesis
⦿Adipose
◼Stimulates lipolysis and release of fatty acids