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CARBOHYDRATES

METABOLISM

CARBOHYDRATES

METABOLISM

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Metabolism

Metabolism is a set of processes performedby the living beings that allow them to

interchange matter and energy with theirenvironment.

The living beings use the metabolic processesto grow and organize themselves internally.

The metabolism consists of two basic types ofinterdependent phases, the catabolism andthe anabolism.

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Catabolism “breakingdown”Catabolism means disintegration.Catabolism implies release of

energy.

They are exergonic.

In a catabolic reaction largemolecules are broken down into

smaller ones.

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Anabolism “building up”

 nabolism means reorganization. nabolism implies capture of

energy.

 nabolic reactions build newmolecules and!or store energy.

They are endergonic.

In an anabolic reaction smallmolecules "oin to make largerones.

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MetabolicPathway

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Stage 1 – igestion o!Carbohydrates

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Stage "" # $lycolysis

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$lycolysis

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$lycogen Metabolism%$lycogenisis&

$tores glucose by convertingglucose to glycogen.

%perates when high levels of

glucose&'&phosphate are formedin the (rst reaction of glycolysis.

)oes not operate when energy

stores *glycogen+ are full, whichmeans that additional glucose isconverted to body fat.

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$lycogenesis

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$lycogenolysis

lycogen is broken down toglucose.

lucose molecules are removed

one by one from the end of theglycogen chain to yield glucose&-&phosphate.

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$lycogenolysis

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Pathways !or Pyru'ate

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1(

)nder aerobic conditions %o*ygen present&+ ,hree#carbon pyru'ate is decarbo*ylated.

 ,wo#carbon acetyl CoA and C- are produced.

  - - pyru'ate

  // // dehydrogenase

  C02C2C2-#  3 0S2CoA 3 4A3

  pyru'ate

  -  //  C02C2S2CoA 3 C-  3 4A0

acetyl CoA

Pyruvate: Aerobic Conditions

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Citric Acid Cycle %5rebs Cycle&

Mitochondrial matri*6nergy 7ield  A,P and more e#

Acetyl#CoA combines with -*aloacetate to!orm Citric acid

Citric Acid changed to Alpha#5etoglutaratethen to a -*aloacetate.

Cycle always re!orming -*aloacetate.5rebs Cycle Product

◦ A,P#)sable energy◦ 84A0#$oes to 6,C

◦ 9A0 #$oes to 6,C

◦ C- #:yproduct

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 6lectron ,ransport Chain

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 ,he 6lectron ,ransportChain ,he 6,C is a series o! proteins

located in the mitochondrialmembrane.

"t uses high energy electrons !romthe 4A0 and 9A0 pro'ided bythe 5rebs Cycle to mo'e 03%protons& across the concentration

gradient. ,hese protons pass back down theconcentration gradient through A,Psynthase to !orm A,P.

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Anaerobic <espiration

"! o*ygen is not present+ theproducts o! glycolysis %pyru'icacid and 4A0& will enter an

alternati'e process calleder!entation"

9ermentation pro'ides enough

A,P and recycles 4A0 into4A3 so that glycolysis maycontinue until more o*ygenbecomes a'ailable.

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 ,wo ,ypes o! 9ermentation

=actic Acid -ccurs in muscle cells in thebody.

A!ter glycolysis   pyru'ic acidchanged to lactic acid

=actic acid is a waste product o!

!ermentation that will build upand cause your muscles to “burn”during hard e*ercise.

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Alcoholic 9ermentationAlcoholic !ermentation is aprocess used by many yeasts andplants.

Also uses the products o!

glycolysis %4A0 and pyru'icacid& to pro'ide enough 4A3and A,P !or glycolysis to

continue. 6thyl alcohol and carbon dio*ide

are the end products

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#$uconeo%enesis & synt'esis o

%$ucose ro! noncarbo'ydrate

(recursors

iver and kidney are ma"or sites ofglucose synthesis

Main precursors/ lactate, pyruvate,glycerol and some amino acids

0nder fasting conditions,gluconeogenesis supplies almost allof the body1s glucose

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Reactions in #$uconeo%enesis

1. Phosphoenolpyru'ate is !ormed !rom pyru'ate by way o!o*aloacetate through the action o! pyru'ate carbo*ylase andphosphoenolpyru'ate carbo*ykinase.

Pyru'ate 3 C- 3 A,P 3 0- → o*aloacetate 3 AP 3 Pi 3 03-*aloacetate 3 $,P → phosphoenolpyru'ate 3 $P 3 C-

. 9ructose >#phosphate is !ormed !rom !ructose 1+>#bisphosphate.6n?yme # !ructose

1+>#bisphosphatase.

9ructose 1+>#bisphosphate 3 0- → !ructose >#phosphate 3 Pi

. $lucose is !ormed by hydrolysis o! glucose >#phosphate in areaction cataly?ed by glucose >#phosphatase.

$lucose >#phosphate 3 0- → glucose 3 Pi

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 ,0A45 7-)@

Prepared by

Ma. =uisa B. Palomo"'y Boyce A. :uan:S C06M"S,<7 "#A