M E TA B O L I S M : A N A B O L I S M

A N D C ATA B O L I S M
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“ I N O R D E R T O S U C C E E D , W E M U S T F I R S T B E L I E V E T H AT W E C A N ”
* N I KO S K A Z A N T Z A K I S
435 Biochemistry Team
OBJECTIVES:
•Understand the concept of metabolic
pathway.
•Identify types & characters of
metabolic pathways- anabolic and
catabolic.
•Identify ATP as the energy currency of
cells.

435 Biochemistry Team

 Note : Catabolism
Metabolism : All the chemical reactions taking place give energy to
inside a cell .(every chemical reaction in our body when anabolism.
we put it together it is called “metabolism”) It consist of :

Anabolic: energy consuming Pathways. Catabolic: energy producing Pathways.

- Endergonic function. - Exergonic function.
- it’s need energy to Build. - it’s produce energy by breaking down.

# They are collectively known as metabolism .

What is pathway ?
- A multi step sequence of chemical reactions.
The product of first reaction Becomes a substrate for second reaction.
- metabolism: Integrated pathways : .
‫يعني ال‬pathways ‫)هذي اذا جمعناها سوا وصار ناتج التفاعل االول هو المادة المتفاعلة للتفاعل الثاني يصير اسمه‬metabolism(
- example of a metabolic pathway: Glycolysis.
- “ The Metabolic Map”: Different pathways can intersect forming
an integrated and purposeful network of chemical reactions
- Pathways that regenerate a component are called cycles.

435 Biochemistry Team

 Metabolic Pathways Classification

catabolic anabolic

• Precursor molecules into complex molecules.

• Endergonic reactions require ATP.

• Divergent process.

Amphibolic Pathways
Amphi = Dual, amphibolic: dual pathway
-Example:
- Krebs cycle is mainly a catabolic cycle, but
with some anabolic features,
(e.g., part of Krebs cycle is used for the synthesis
of glucose from amino acids)
Therefore, Krebs cycle is amphibolic.
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Catabolism Vs Anabolism

Anabolic Catabolic
 Simple to complex  Complex to simple
molecules molecules

 Endergonic  Exergonic
 Involves reductions  Involves oxidations
 Requires NADPH  Requires NAD+
 Divergent process  Convergent process

435 Biochemistry Team

 Energy Currency : ATP
*Notes:
ATP + H2O Hydrolysis ADP + PI  The free energy liberated in the hydrolysis of
 ATP produces energy by breaking one ATP is used to drive the endergonic reactions.
phosphate , they are known as high-  Catabolism reactions produce energy in the
energy phosphate bonds . form of ATP (exergonic) . This reactions have
* check the figure bellow * an enzyme that will link “join” the phosphate
and the ADP to form ATP when the feul
molecule is oxidized.
 ATP gives energy to the anabolism reactions
by breaking the phosphate bond
(endergonic). This reactions have an enzyme
that will break the bond from the
ATP to give ADP and phosphate.
 This is a point where we will have coupling of
and reactions at the
level of ATP, because endergonic requires
energy from ATP and exergonic produces
energy in the form of ATP.
 This ATP- ADP cycle is the fundamental mode of
energy exchange in biological systems.

435 Biochemistry Team

 Oxidation-Reduction In Metabolism
- Oxidation lose electron , lose H
- Reduction receive electron , gain H

Fatty acids

carbohydrate Amino acids

- Catabolic is OXIDATION pathway, and Anabolic is REDUCTION pathway . Energy rich

- In oxidation energy-rich compounds are oxidized (broken down). compounds

Gives electron receives electron

(oxidation of energy-rich compounds = reduction of coenzymes )

*more explanation in the next slide*

^^
435 Biochemistry Team
 Oxidation-Reduction In Metabolism (Explanation)

Metabolism
- Food is getting oxidized - when something get oxidized something else will get reduced, the transform of electrons have to
be there - so the coenzymes are the ones whose getting reduced.
- Coenzymes got reduced because they received electrons from the food that have been oxidized and becomes energy-
rich .
Oxidative Phosphorylation
- the reduced coenzymes will be oxidized to produced NAD+ and FAD , they will give their electrons to the oxygen. The
oxygen accept the electron from NADH and FADH2 , that’s why we call it cellular respiration and the energy is captured
as
ADP + Pi = ATP . OXIDIZED
AND
SUMMERY : CATABOLIC PROSSES BECOME
REDUCED NADH and NAD+ and FAD
AND FADH2
BECOME
OXIDIZED
GIVE GIVE
FOOD ELECTRON ELECTRON
Coenzymes TO
NAD+ and FAD The Oxidative
Phosphorylation
OXYGEN start
CAPTURE
ENERGY AS H2O REDUCED
ATP “WATER” INTO

435 Biochemistry Team

 REGULATION OF METABOLISM REGULATE THE REACTIONS …

Withier it’s catabolism or anabolism, it should be according to the cell’s need .

For regulating it needs signals …

1- Intracellular signals: (inside cell)

• Substrate availability (if the substrates needed are available in cell).
. ‫ اذا فيه نقص ما يتم التفاعل‬، ‫اذا كل المواد الي نحتاجها للتفاعل موجودة يبدأ التفاعل‬

• Product inhibition (ability of the products to control the metabolism ).

. ‫ وعند حدوث نقص تبدأ التفاعل مره ثانيه‬، ‫عند توافر مواد ناتجة كثيرة و كافية للخلية هنا الخلية توقف التفاعل‬

• Allosteric activators(allosteric regulation is the regulation of enzymes or other

proteins by the binding of an effector molecule at the protein's allosteric site; that
is, a site other than the protein's active site).
2- Intercellular communications: (between cells)
Chemical signaling (hormones) from outside the cell :
Second messenger: cAMP, cGMP,
Ca\ phosphatidylinositol.
‫ هذي المستقبالت تنقل الرساله‬، ‫ لما توصل للخلية يكون فيه على سطح الخلية مستقبالت لها‬. ‫الهرمونات لما تفرز يكون معها رساله معينه تبي توصلها لخليه محددة‬
‫الى الخلية عن طريق السكند ماسنجرز‬
435 Biochemistry Team
 Intracellular signals in the REGULATION OF METABOLISM *summary*
Withier it’s catabolism or anabolism, it should be according to the cell’s need .
For regulating it needs signals …

Intracellular signals (within the cell ) :

 This kind of regulation is very fast !

Allosteric activator Substrate availability

allosteric regulation is Product inhibition
- if substrate is less  it
the regulation of
Feedback inhibition to won’t activate it.
enzymes or other
shut off the enzyme - If the substrate needed is
proteins by the binding avalible  it will activate it
of an effector molecule
and will make product
at the protein's allosteric
- if there’re lots of products
site; that is, a site other
there will be ..
than the protein's active
site 435 Biochemistry Team
 Metabolic Fuel Substance used for energy production.
• The most common metabolic fuels are :
CARBOHYDRATES  LIPIDS  PROTEINS (little existent).

• These are: glucose, fatty acids and amino acids.

• CARBOHYDRATES from inside and outside the body can be

converted into GLUCOSE .

• GLUCOSE is the major metabolic fuel of most tissues .

435 Biochemistry Team

 Summary
 Metabolism: chemical reactions  Most pathways can be classified:
taking place inside a cell. • Catabolic (energy producing) pathway.
• Anabolic (energy consuming) pathway.
 Metabolic pathways: (e.g.: glycolysis)
• Multi-steps sequence of chemical
reactions.
• A product of 1st reaction becomes a
substrate for 2nd reaction.
• Integrated pathways  metabolism.

 Metabolic map: different pathways

can intersect forming an integrated
and purposeful network of chemical
* Complex  simple. * Simple  complex.
reactions.
* Exergonic. * Endergonic.
* Oxidations. * Reductions.
 Pathways that regenerate a
* Requires NAD+. * Requires NADH.
component are called cycles.
* Convergent. * Divergent.

435 Biochemistry Team

Summary
 Amphibolic (e.g.: Krebs cycle):  Difference between oxidization and
It’s mainly a catabolic cycle but with reduction:
some anabolic features.
oxidation reduction
 Hydrolysis of ATP is used to drive the
endergonic reactions. Loss of hydrogen Gain of hydrogen
ATP + H2O  ADP + Pi + energy Loss of electrons Gain of electrons
 ATP is formed from ADP and Pi
when fuel molecules are oxidized.  Regulation of metabolism:
ADP + Pi  ATP
 ATP-ADP cycles is the fundamental Intracellular Intercellular
mode of energy exchange in signaling communications
biological systems. • Substrate availability • Chemical signaling
• Product inhibition (hormones):
 Fuel molecules: • Allosteric modulator second messenger
• Glucose is the major metabolic fuel. (activator/inhibitor) cAMP, cGMP
• Fatty acids. Ca/phosphatidylinositol
• Amino acids (little extent).
435 Biochemistry Team
 Videos
- Overview of Metabolism - Anabolism and Catabolism :
https://www.youtube.com/watch?v=ST1UWnenOo0&index=4&list=PLgL
Exqo2buqtRLeP75l38GMBNjS7t7ReP

-important Video:
https://youtu.be/fWQKlMqzkgo

435 Biochemistry Team

 MCQ’s 8.C
1- Breaking one phosphate bond from an ATP molecule in metabolism : 6.B
a. Store energy b. produce energy c. reduce molecule weight
5.C
2- Catabolism reactions producing energy in the form of ATP :
4.B
a. exergonic b. endergonic c. non
3.B
2.A
3- Where we will have coupling of endergonic and exergonic reactions ? 1.B
a. Metabolism of glucose b. at ATP level c. never
4- Receive electron :
a. Transfer NADH into NAD+ b. Transfer NAD+ into NADH c. Non
5- In cellular respiration energy captured as :
a. NADH and FADH b. ADP c. ATP
6- When there’re lots of products of Substrate availability
there will be :
a. Intercellular communications b. Product inhibition c. Allosteric activator
7- First messenger in metabolism regulation :
a. Blood b. Molecules that are generated inside the cell c. Hormone

435 Biochemistry Team

 13.F
12.A
11.T
9- The major metabolic fuel of most tissues :
10.C
a. Fatty acids b. Glucose c. Amino acids
9.B
10: Pathways that regenerate a component are called:
a. Anabolism.
b. Catabolism.
c. Cycles.
11: The Metabolic Map is: Different pathways can intersect forming an integrated and
purposeful networks of chemical reactions. (T) or (F)
12: cells use hormones for:
a. Intracellular communications.
b. Intracellular signals.
13: IF the substrate availability is high that means the cell is going to shut down the reaction.
(T)or(F)

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