Paper Topic:

Cellular Metabolism

: Cellular Metabolism

p : language Title : `The mitochondria and the cytoplasm of mammalian cells have distinct roles

in intermediary metabolism , but the overall metabolism of the cell depends on their cooperation . Discuss . `

Guidelines

You are expected to answer this with reference to the metabolic pathways that have been covered in the lectures

I .E

-Glycolysis

-TCA cycle

-Carbohydrate metabolism (gluconeogenesis , pentose phosphate pathway etc

-Fat metabolism (beta Oxidation and oxidation of glycerol

-Nitrogen Metabolism (e .g . urea cycle

Where citations are appropriate in the

text , they should be linked to a reference list at the end in Harvard style

The following points are suggested to focus your reading and thinking before

Writing your answer they are not intended to constrain your approach or essay structure

Consider where in the mammalian cell different metabolic processes occur

What metabolites are transferred between cytoplasm and mitochondria , and vice versa ? Is there any part of metabolism that can take place wholly in the cytoplasm

Illustrate your answer with appropriate diagrams

The mitochondria contain two membranes , an inner membrane (that is selectively permeable and is thrown into folds or cristae in to increase the surface area ) and the outer membrane (which does not offer a permeable barrier . The outer membrane contains several enzymes such as monamine oxidase , acyl-COA synthetase , glycerolphosphate acyltransferase and phospholipase A2 . In the inter-membrane space region adenylyl kinase and creatine kinase are present . Phsopholipid cardiolipin is present in the inner membrane . The mitochondrial matrix contains several enzymes that play an important role in the citric acid cycle and the beta-oxidation of fatty acids (Beattie , D .S , 2006 568-572 , and Mayes ,

.A , 2003 , 137

Glycolysis does not utilize oxygen and it involves conversion of glucose into pyruvate . This pyruvate is converted into lactic acid and is transported into the liver , or can be transported through the inner membrane of the mitochondria to enter the Kreb 's cycle , TCA cycle or the Citric Acid cycle (Applegate , E , 2001 , 353-360

Several enzymes are present on the mitochondrial inner membrane Succinate dehydrogenase and 3-hydroxybutryrate dehydrogenase is present in the inside of the membrane , whereas , glycerol 3-phosphate dehydrogenase is present on the outside (Mayes ,

.A , 2003 , 137

Various transport systems are located in the mitochondria to help transport substance across the inner membrane . The transport systems can move several substrates opposing concentration gradients . These transporters include monocarboxylate transporters (that transports pyruvate into the mitochondria and OH- ions into the cytoplasm from the mitochondria , dicarboxylate transporter (that transport phosphate ions into the mitochondria and malate into the cytoplasm , tricarboxylate transporter (that transport malate into the mitochondria , and citrate into the cytoplasm , phosphate transporter (that transport phosphate ions into the mitochondria and hydrogen ions into the cytoplasm adenine nucleotide translocase (that transports ADP into the mitochondria and ATP into the cytoplasm , Aspartate-glutamate transporter (that transports glutamate into the mitochondria and aspartate into the cytoplasm ) and malate-alpha-keoglurate transporter (that transports malate into the mitochondria and alpha-ketoglutarate into the cytoplasm (Beattie , D .S , 2006 , 568-572...

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