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Online Counseling Resource
YCMOU ELearning Drive…
School of Architecture, Science and Technology
Yashwantrao Chavan Maharashtra
Open University, Nashik – 422222, India
OC-SBT/ SBI/ SGS034-CP1-04
Introduction
Programmes and Courses
 SEP – SBT034 – Unit 01
 SEP – SBI034 – Unit 01
 SEP – SGS034 – Unit 01
School of Science and Technology, Online Counseling Resource…
Credits

Academic Inputs by
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Arun Punaji More.
M.Sc. (Microbiology)
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Experience: 11 Years

[email protected]
School of Science and Technology, Online Counseling Resource…
How to Use This Resource

Counselor at each study center should use this presentation to deliver
lecture of 40-60 minutes during Face-To-Face counseling.

Discussion about students difficulties or tutorial with assignments should
follow the lecture for about 40-60 minutes.

Handouts (with 6 slides on each A4 size page) of this presentation should
be provided to each student.

Each student should discuss on the discussion forum all the terms which
could not be understood. This will improve his writing skills and enhance
knowledge level about topics, which shall be immensely useful for end
exam.
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Appear several times, for all the Self-Tests, available for this course.
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Student can use handouts for last minutes preparation just before end
exam.
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Learning Objectives
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After studying this module, you should be
able to:
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Define catabolism in plants and mammals.
Describe Different biochemical reactions
involved in catabolism.
Describe various biochemical pathways of
catabolic metabolism and its Significances
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Introduction - 1
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Catabolism is set of biochemical reactions
involved in the production of chemical
energy and building blocks for the
synthesis of new cells and tissues
thereafter.
Carbohydrates, fats and proteins are
source of energy which is released by
catabolism.
90% of this energy comes from the
catabolism of carbohydrates and fats.
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Introduction - 2
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10 to 15% of the energy comes from the
catabolism of proteins.
90% of this energy comes from the
catabolism of carbohydrates and fats.
10 to 15% of the energy comes from the
catabolism of proteins.
In this presentation, you will get overview
of catabolism of carbohydrates, fats and
proteins.
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Catabolism - 1
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Catabolism is set of biochemical reactions
of breaking down carbohydrates, fats and
proteins to obtain energy in chemical form
to drive different biosynthesis processes
and mechanical jobs of cells.
Catabolic reactions are basically oxidation
reactions which uses oxygen.
Catabolic reactions produce chemical
energy in forms of ATP molecules and
NADPH.
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Catabolism - 2
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The catabolism is thus breaking down of
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Carbohydrates
Fats
proteins
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Catabolism Pathway-1
 Catabolic pathways in brief:Three stages of catabolism:• In first stage there is breakdown of
Large complex macromolecules
of energy source into basic
building blocks such as glucose,
amino acids and fatty acids and
glycerol.
• In second stage these simple
building blocks are oxidized to
common metabolite, Acetyl CoA to
release the free energy required
to drive the anabolic reactions.
• In third stage energy rich electron
released in citric acid cycle is fed
into respiratory chain to
synthesize ATP molecules.
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Catabolism of Carbohydrates
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Catabolism of carbohydrates is carried out
by the set of biochemical processes known
as glycolysis or Embden-Myerof pathway.
The complete glycolysis is shown by
chemical reaction as follow:
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C6H12O6 +6O2 + 6H2O +6CO2 + 686
Kcal/mole
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Role of ATP Molecules
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Catabolism of Carbohydrates
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The total glycolysis of carbohydrates is carried
out in two stages:
 In first stage of glycolysis the carbohydrates
are converted into pyruvic acid as follow:
 D-glucose +2Pi +2ADP +2NAD+ 2Pyruvate
+2ATP +2NADH.
 This first stage of glycolysis does not require
oxygen to convert the glucose molecule into
pyruvic acid.
 In the second stage of glycolysis pyruvic acid
is oxidized to CO2 and water by citric acid
cycle.
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Catabolism of Fats-1
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Energy content of fats is 9Kcal/g; whereas
the energy content of carbohydrates is
4Kcal/g.
In the few minutes of exercise, ATP and
glycogen reserve of skeleton muscles are
used, thereafter fats are the major source
of energy for the prolonged muscular
activity.
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Catabolism of Fats-2
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Since the fats are oxidized aerobically via
β-oxidation, consumption of oxygen
increases 16 folds during the first five
minutes of intense muscular activity.
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Catabolism of Fats-3
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Fats are oxidized solely in mitochondria.
The free fatty acids in cytosol can not pass
membranes of mitochondria and therefore
have to undergo series of enzymatic
reactions which convert the fatty acids to
fatty acyl-CoA.
Now this fatty acyl CoA is oxidized in
mitochondria to produce energy in form of
ATP molecules.
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Catabolism of Fats-4
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In mitochondria fatty acids in form of fatty
acyl CoA is oxidized in two stages:
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In the first stage fatty acyl CoA is oxidized to
Acetyl-CoA and ATP .
In the second stage the fatty acids are
oxidized to via citric acid cycle to CO2 and
H2O.
CH3(CH2)14CO2H +23O2 <--> 16CO2
+16H2O+ 130 ATP
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Catabolism of Proteins-1
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Catabolism of proteins contribute only
10% to 15% of total energy.
Amino acids produced after the breaking
down of proteins enter the catabolic
pathways .
The alpha amino group of 20 amino acids
is removed during the first stage of
degradation of amino acids by enzyme,
aminotransferase.
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Catabolism of Proteins-2
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If this removed alpha amino group is not
utilized for the synthesis of new amino
acid of any other nitrogenous compound
then it is excreted from the body in form
of urea.
Aminotransferase transfer amino group
from alpha carbon of amino acid to alpha
ketoglutarate, producing alpha keto acid
and L-glutamate.
L-glutamate is common acceptor of amino
group from amino acids.
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Catabolism of Proteins-3
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L-glutamate thus formed is either utilized
in biosynthesis reactions or enter into
citric acid cycle.
However different amino acids enter the
citric acid cycle as different intermidiates.
For example, arginine, histidine,
glutamine and proline enter the citric acid
cycle as glutamate.
Isoleucine, methionine and valine enter
the citric acid cycle as succinyl-CoA.
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Catabolism of Proteins-4
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Phenylalanine and tyrosine enter the citric
acid cycle as fumarate.
Aspartate and asparagine enter the citric
acid cycle as oxaloacetate.
Phenylalanine, tyrosine, leucine lysine
tryptophan enter the citric acid cycle as
acetyl-CoA via acetoacetate-CoA.
Alanine, threonine, glycine serine and
cysteine enter the citric acid cycle as
acetyl-CoA via pyruvate .
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Hormonal Control of Catabolism
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Metabolism of carbohydrates is controlled
by following hormones:
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Insulin
Glucagon
Epinephrine
Glucocoticosteroid
Thyroid hormones
Glucagon and epinephrine have opposite
effects to that of insulin.
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Hormonal Control of Catabolism-2
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Insulin : Insulin control uptake of glucose by
cells.
 Insulin stimulates glycolysis.
 Insulin inhibits gluconeogenesis.
 Insulin stimulates synthesis of
triglycerol and its breakdown.
 Insulin stimulates synthesis of glycogen
and its breakdown.
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Hormonal Control of Catabolism-3
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Glucagon:
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It is secreted by alpha cells of pancreas in
response to low blood glucose level.
Glucagon stimulates glycogen breakdown.
Epinephrine (adrenaline) :
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It is secreted by adrenal gland.
Epinephrine stimulates breakdown of glycogen
to glucose 1-phosphate which then converted
into glucose 6-phosphate.
© 2007, YCMOU. All Rights Reserved.
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What We Learn…..
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Concept of catabolism.
Carbohydrates, fats and proteins are source of
energy which is released by catabolism.
Catabolic reactions are basically oxidation
reactions which uses oxygen.
Catabolism of proteins contribute only 10% to
15% of total energy.
L-glutamate is common acceptor of amino
group from amino acids.
L-glutamate is common acceptor of amino
group from amino acids.
School of Science and Technology, Online Counseling Resource…
Critical Thinking Question

In healthy mammals which organic
compound is predominantly involved in
catabolism as starting material?
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Tips for Critical Thinking Question
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Organic compound that is abundantly
available as energy source in nature.
School of Science and Technology, Online Counseling Resource…
Study Tips
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Book
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Title: Fundamentals of Biochemistry
Author: Dr. J. L Jain
Publication: W S. Chand and Co. , New Delhi.
Book
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Title: Principles of Biochemistry
Author: Dr. H Robert Horton
Publication: W S. Chand and Co. , New Delhi.
End of the Presentation
Thank You !