Week 1B: Metabolism Basics, Organs and metabolic pathways, glycolysis and pentose phosphate pathway, TCA cycle Flashcards
HC03-06
HC03: Energy methods out of glycolysis
-NADH
-ATP
Requirement of free energy for:
-Mechanical work: cellular transport, muscle contraction
-Active transport of molecules and ions
-Synthesis of macromolecules from building blocks
-Thermogenesis
Energy is obtained from the … of food
oxidation
Metabolism consists of … pathways of chemical reactions
Interconnected
Anabolism
Synthesis of complex molecules
- useful energy + simple precursors > complex molecules
- Gluconeogenesis of glucose from pyruvate or lactate for example
Catabolism
Breakdown
> Carbohydrates and fats to CO2, H2O and useful energy
> Glycolysis of glucose
Metabolism is regulated, why?
You don’t want to make something and break it down simultaneously
-Glycolysis yields 2 ATP
-Gluconeogenesis costs 6 ATP
> organize the fluxes
The currency of free energy
ATP: adenosine triphosphate
ATP structure
Adenine, ribose and 3 phosphates
How many energy rich bonds does ATP have and how are they called?
Two phosphoanhydride bonds
> Gamma and beta phosphates are energy rich bond
> the outer bond (gamma) is between two phosphates (both negatively charged)
> alpha bond not between two phosphates, lower energy
ATP can be converted to … to release energy
ADP, or AMP
dG and entropy formula
dG = dH - T*dS
dG: delta Gibbs free energy
dH: delta enthalpy (heat content)
dS: entropy: degree of disorder
ATP>ADP+Pi is an … reaction (hydrolysis)
Exergonic (energy released for Gibbs free energy)
What is the dG0’ of ATP > ADP
-30.5 kJ/mole
What if dG0’ is negative?
Spontaneous reaction
> can be coupled to an energetically unfavorable reaction
Why are phosphoanhydride bonds energy rich
-A lot of resonance structures available where the energy can be located
- Force of the negative charges who lay in close proximity
> ATP 4- > outer phosphate 2- and middle and inner 1-
dG0’ of ATP > AMP + PPi. When is this used?
dG0’=-45.6 kJ/mole
> used if the energetically unfavorable reaction has a dG0’ > 30.5 kJ/mole
In which organisms is the ATP-ADP cycle the fundamental mode of energy exchange?
All
Why are phosphoenolpyruvate, 1,3-BPG and creatine phosphate, with a more negative dG0’ for conversion less good as energy currency
These compounds can be used to phosphorylate ATP fro ADP
> you can synthesize ATP without oxidative phosphorylation in mitochondria if higher energy molecules are oxidized. If the currency is a maximal energy carrier, this is not easily possible.
How is it called if high energy compounds are used/oxidized to make ATP? How much of the ATP is made through this mechanism?
Substrate-level phosphorylation (10%)
Creatine usage before exercise
In muscle cells, you make creatine phosphate using ATP before the sport in rest
> During exercise, creatine phosphate can be used to synthesize ATP as early reserve for substrate-level phosphorylation
> for sudden exercise
> oxygen cannot hold up with muscle activity, the oxidative phosphorylation cannot keep up with the use of ATP, creatine supplementation to make ATP with substrate level phosphorylation on short term
Creatine is synthesized in our …
Liver and kidneys
Creatine phosphate + ADP <=> ATP + creatine: enzyme?
Creatine kinase
ADP+ADP <=> ATP + AMP. Explain and enzyme
It costs two ATP to regenerate ATP from AMP. Enzyme is adenylate kinase
> this reaction is used when ATP levels run low in human cells including muscle. Produce ATP from ADP for extra energy
> AMP is useless until regeneration by AMP kinase if there is much AMP