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Metabolism

9

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objectivesUnderstand the concept of metabolic pathways.

Identify types and characteristics of metabolic pathways:(anabolic and catabolic)

Identify ATP as the energy source for cells

metabolismMetabolism consists of:

Anabolic pathways:Consuming energy(Endergenic) building up

Catabolic pathways:Producing energy(Exergenic) breaking down

All the chemical reactions taking place inside a cell are collectively known as METABOLISM

Metabolic Pathway:➢ A multi-step sequence of chemical reactions➢ A product of first reaction becomes a substrate for second reaction ➢ Integrated pathways: Metabolism

Pathway Vs chemical reaction

Note :A ——> BB——>CC——>DEach product is a substrate for another reaction Note : Pathway is a Sequence of reactions

The Metabolic map● Different pathways can intersect(تتقاطع

( مكونین شبكة متكاملة forming an integrated and purposeful network of chemical reactions “The Metabolic Map”

● Pathways that regenerate or produce a component are called cycles

Note : don’t memorize this map just get the idea

فكرتھا زي قوقل ماب ولو واحد وصف لك تروح مكان بیقول لك تمشي لین جامعة الملك سعود من طریق االمام وبعدین تاخذ یمین... كذا ما راح تقدر تجیھ اال من طریق

واحد لكن لما یعطیك خریطة او اللوكیشن بالجوال راح یعطیك قوقل ماب اكثر منطریق عشان تصل

Dr’s note :The porpoises of metabolic map:1-to get a clear vision2- if there are any changes in one pathway it will help us to know what other pathways will be affected

Pathway classified into

Catabolic pathway Anabolic

Divergent process

Precursor molecules into

complexmolecules

Stage 1 : hydrolyze the complex

molecule to their components building

blocks

Stage 2: convert the

building blocks into Acetyl CoA

Stage3: oxidation acetyl CoA,oxidative

phosphorylation To produce ATP

Energetic reaction

require ATP

Note : it breaks down so many complex molecules

Note : it will make more complex and multiple different molecules from few building blocks

Note : 1- Energetic: energy consuming 2- Divergent : We can make complex molecules from few building blocks

Requires NADPH

Clas

ses

of

met

abolism

Anabolic

Catabolic

EndergonicRequires ATP

Simple to complexmolecule

Involves oxidationsLose H+ (electron)

ExergonicProducing ATP

Complex to simplemolecules

Involves reductionsGain H+ (electron)

Convergent process

Divergent processRequires NAD+

Comparison of catabolic and anabolic pathways

Energy currency : ATPATP H O ADP P 2 i

Adenosine Triphosphate= ATPwhich consists of ( 3 Phosphate groups + Nitrogen Base (Adenosine)).When ATP loses its 3rd phosphate group, will become ADP + P group and the energy released (when fuel molecules are oxidized).

● The free energy liberated in the hydrolysis of ATP is used to drive the endergonic reactions

● ATP is formed from ADP and Pi when fuel molecules are oxidized

● This ATP-ADP cycle is the fundamental mode of energy exchange in biological systems

Note : if you hydrolyze them , they will produce a lot of energy

i

Amphibolic Pathway1- Amphi = Dual, amphibolic: dual pathway (both catabolic and anabolic).

2- 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.

Regulation Of Metabolism

Intercellular communications(outside the cell)

Intracellular signals(inside the cell)

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)

Substrate availability:

if the substrates needed are

available in cell

Chemical signaling

Second messengersProduct

inhibition:a type of enzyme

inhibition: it is ability of the products to control the metabolism

Note : A hormone (1st) binds to a receptor outside the cell, leading to the activation of cell messengers (2nd) inside the cell.

(hormones or neurotransmitters):

first messenger

-(cAMP, cGMP) c= cyclic m= mono

-(Ca++ /phosphatidylinositol)

Just know the names

Oxidation & Reduction in metabolism

- Energy rich compounds

Reduction“anabolic”

Oxidation“catabolic”

loss of electrons

Loss of hydrogen

Gain of hydrogen

gain of electrons

They are E-rich reduced coenzymes, gain hydrogen. Oxidation

NAD= Nicotin-amide Adenine Di-nucleotide From NADH to NAD+ (oxidation) “loss of hydrogen” From NAD+ to NADH (reduction) “gain of hydrogen”

في عملیات األیض(metabolism)

یحدث نقل اإللكترونات من الغذاء(oxidized) إلى الكوانزیم(reduced)

(reducing Agent)

(Oxidation Agent)

used for energy

production

CARBOHYDRATES (Glucose): the major metabolic fuel of most

tissues, major source of energy.

LIPIDS (fatty acids):major source of energy

PROTEINS (Amino acids):

a minor source of energy -little existent-

Electron transport

chain

Take home messageMetabolism is the sum of all biochemical pathways that occur inside the cells. A metabolic pathway is a multistep sequences of enzyme-catalyzed reactions.

Catabolism is a convergent process that provides energy to cells in the form of ATP.Anabolism is a divergent process that consumes energy for the synthesis of complex molecules.

Metabolic pathways are tightly regulated and highly integrated.

ATP is the energy currency of the cells

Quiz Q5: what is the pathway that Producing energy?

A) Anabolic Pathway B) Catabolic Pathway C) Both D) None of the above

Q6: ATP is

A) Adenosine twophosphate

B) Adenotine Triphosphate C) Adenosine Triphosphate D) Adrenal Triphosphate

Q7: Which types of pathways that Krebs cycle use :

A) Anabolic Pathway B) Catabolic Pathway C) Amphipolic D) None of the above

Q8: From NADH to NAD+ by

A) Oxidation reaction B) reduction reaction C) Both D) none of them

Q1:what is the pathway that consumes ATP?Q2:what is the pathway reaction and give an example?Q3: What is the reduction reaction ?Q4: Hydrolysis of ATP will produce ?

MCQs SAQ

1)B2)C3)C4)A

MCQs answers

A1: Anabolic Plat wayA2: multi-step sequence of chemical reactions like glycolysis A3: gains electron or H+A4: ADP+P (free energy)

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