Summary
Summary Carbohydrate Metabolism
- Institution
- University Of Cape Town (UCT)
Carbohydrate Metabolism summary including glycogenesis, glycogenolysis, pentose phosphate pathway and regulation of all mechanisms
[Show more]
Content preview
Carbohydrate MetabolismGlycogen Metabolism
Glycogenolysis à occurs in liver and muscles
• Glycogen à glucose when needed
Gluconeogensis Glycogenolysis
Glucose-6-phosphatase in ER of kidney and Liver + muscles
liver leads to location of reaction
Not allowed in skeletal muscle and brain
• Glycogen phosphorylase àprinciple enzyme of glycogen catabolism
o Glycogen -> G1P
o ∆G0 is + 3kJ/mol
o Reaction uses phosphate – reaction driven by high intracellular phosphate
levels: [Pi] ~ 100 x [glucose 1-P]
§ Dependent on ratio of G1P to inorganic phosphate
§ Allows for forward reaction to be favoured
o Shortening glycogen chain
à glycogen = polymer of glucose subunits linked by a(1à4) bonds
• Synthesized and stored when glucose levels are high
A+B →C+D
[𝑪][𝑫]
∆G = ∆Go + RT ln [𝑨][𝑩]
• Phosphoglucomutase à
o G1P -> G6P
o G6P used in glycolysis – no additional ATP needed (only the case when rxn
occurs in muscles)
§ Favorable to the cell!
§ Bypasses first step of glycolysis that does require ATP to add
phosphate to glucose
§ If glycogenolysis occurs in the liver à G6P or G1P must be converted
into glucose before being transported in bloodstream to muscle cells
§ ATP saving mechanism is only relevant in muscle cells
o Phosphate position is moved from carbon 1 to carbon 6
, o Reaction uses phosphate
§ Rxn is driven by high intracellular phosphate levels
*excess glucose is stored as glycogen in the liver
Glycogenesis à
• Glucose -> glycogen
• UDP- glucose pyrophosphorylase
o Glucose -> UDPG
o High concentration of phosphate in the liver favours glycogenolysis
o Glucose units are activated for transfer by formation of sugar nucleotides
§ Sugar nucleotides are used in synthesis of oligo and polysaccharides
o Addition of nucleotides activates molecules for subsequent reactions
o Mechanism =
§ Attack by a phosphate oxygen of G1P on the a-phosphorous of UTP
§ Loss of pyrophosphate anion
• 1 phosphate from G1P and 1 from UTP used
• Hydrolysis of pyrophosphate drives reaction forward
• UDP glucose is the glucose donor in glycogen synthesis
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller erinsnotes. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R100,00. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
72042 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy summaries for 14 years now