Write the balanced equation for the catabolism of six...

Key Concepts

Pentose Phosphate Pathway

This metabolic pathway serves as an alternative route to glycolysis, where glucose-6-phosphate is oxidized to produce NADPH and ribose-5-phosphate. It plays a crucial role in redox balance and biosynthetic processes, such as fatty acid and nucleotide synthesis, by providing reducing equivalents in the form of NADPH.

Gluconeogenesis

Gluconeogenesis is the process by which organisms synthesize glucose from non-carbohydrate precursors. It effectively reverses glycolytic and other catabolic processes to regenerate glucose, ensuring energy supply and maintaining blood sugar levels, especially during fasting or strenuous activity.

Metabolic Stoichiometry

Balancing metabolic reactions involves ensuring that atoms, particularly carbon, hydrogen, oxygen, and phosphorus, are conserved across all reactants and products. This concept is essential in writing overall balanced equations that accurately represent the net conversion of substrates to products in interconnected pathways like the pentose phosphate pathway and gluconeogenesis.

Transcript

00:01 So today we will do problem 14 chapter 16 glycogen metabolism and gluconeogenesis.

00:07 And the question is right the balance equation for the carbon catabolism of six molecule of 6g6p by the pentose phosphate pathway followed by conversion of ribolose 5 phosphate back to g6p by gluconeogenesis right.

00:28 So first we should i think understand the flow of the pentose phosphate pathway which are made of actually mostly made of carbon right so the easiest ways to understand this pathway is to follow the carbon right so the breakdown of the simple molecule glucose and glycolysis provide the first six carbon molecule required for the pentose phosphate pathway so during the first step of glycolysis glucose is transformed, you know, by the addition of a phosphate crop, regenerating glucose 6 -phosphate and other 6 -carbon molecule, the pentose phosphate pharpe can use any available molecules of glucose -6 phosphate, whether they are produced by glyclysis or, you know, other method, right? so now we are ready to enter the first of the two phases of the pentose phosphate pathway, which are actually oxidative and non -acidative phase, right? so the oxidative phase includes, you know, the step one in which the oxidative word of this phase actually comes from the process of oxidation.

02:05 Oxidation is the breakdown of the molecule as it loses at least one of its electron.

02:11 This phase is made up of two irreversible steps.

02:15 So in the first step, the glucose 6 -phosphate is oxidized to form lectone, right? so nadph is produced as a byproduct of this reaction as nad plus.

02:32 Right and is reduced as glucose 6 phosphate is oxidized so following those oxidation of glucose 6 phosphate another reaction catalyzed by different enzyme uses water to form 6 phosphoglyconeate the linear product right so nadph is similar in structure and function as the high energy electron shutter so nadh mentioned in the cellular respiration articles you know nadph has an added phosphate group and is used in the cell to donate its electron just like nadh right so once nadph has denoted its electron it is said to be oxidized so oxidation is equal to loss of electron right so and is now symbolized as an a dhs plus right so so nadh is often used in the reactions that build molecules and occur in high concentration in the cells so that it is readily available for these types of reactions so in the first step we over here we can see this so in the second in the second step next a carbon is removed or cleaved here know and carbon dioxide is released over here right so once again the electron's released from this cleavage and is used to reduce nad plus right to nad ph right so this new five carbon molecule is called the ribolose five phosphate right five phosphate.

04:44 So in the non -oxidative part in the step three we will say the non -oxidative phase is really handy because these reactions are reversible right.

04:55 So over here as we can see the arrows so this allows different molecules to under the pentose phosphate pathway in different areas of the non -oxidative phase and be transformed up until the first molecule of non -oxidative phase which is right ribolose 5 phosphate, you know, so rabelous five phosphate is the precursor to the sugar that makes up a dna and rna and is also a product of the oxidative stage, right? so in the step three, so in the step three, you know, the non -oxidative rabulus five phosphate can be converted into two different five carbon sugar, right? so one is the sugar used to make up dna and rna called ribose -5 -phosphate, and this is the molecule we will focus on, right? so ribolose -5 -phosphate isn't being divided because the carbon count is the same in the next step, right? so anyhow, in the step four, in the step four, the rest of the cycle is now made up of different options that depend on...

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