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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