Lecture 1 Flashcards
What is metabolism?
A collection of coupled and interlinked series of chemical reactions which starts with a particular molecule and converts it to some other molecule(s).
2 main functions of metabolism?
Extract biologically useful energy from cell’s environment.
Synthesise building blocks of cell (simple molecules to complex macromolecules).
2 types of metabolic reactions, and description?
Catabolic - extraction of biologically useful energy.
Anabolic - Synthesise complex structures/molecules from simple ones. Requires input of energy from catabolism.
Six types of chemical reactions in metabolism?
Redox, Ligation requiring ATP cleavage, Isomerisation, Group transfer, Hydrolytic, Addition/removal of function groups.
Example of oxidation reaction?
Succinate + FAD -> Fumarate + FADH2.
Are ligation reactions energy dependent?
Yes.
An example of a ligation reaction?
Pyruvate + CO2 + ATP + H2O Oxoloacetate +ADP + Pi + H+.
Example of isomerisation reaction?
Citrate Isocitrate.
Example of group transfer (involving high energy phosphate)?
Glucose + ATP -> ADP + G-6P
Example of condensation reaction?
Oxaloacetate + Acetyl CoA -> Citryl CoA.
How do condensation reactions work?
Functional groups added to double bonds to form single bonds or removed from single bonds to form double bonds.
3 main components of ATP?
Triphosphate, Ribose, Adenine.
What type of molecule is ATP?
Activated carrier (been conserved through evolution).
What is the reduced form of FAD (oxidised)?
FADH2.
Does oxidation require or release electrons?
Releases.
Is Acetyl CoA an activated carrier?
Yes, of acetyl unit.
3 main parts of coenzyme A?
β-mercapto-ethylamine unit.
Pantothenate unit.
ADP + Extra phosphate.
What are the reactive group for Acetyl CoA?
Sulphur on CoA.
Why are activated carriers typically biologically stable?
Why is this important?
Because they require specific catalysts.
Enables enzymes to control flow of electrons and free energy.
In the absence of a catalyst, what to NADH and FADH2 resist?
Oxidation and release of electrons.
Are ATP and Acetyl CoA hydrolysed in absence of catalyst?
Yes, but slowly.
Is generation of ATP one of the primary roles of catabolism?
Yes.
4 uses of ATP?
Motion,
Active transport,
Biosynthesis,
Signal amplification.
2 uses of ADP?
Oxidation of fuel,
Photosynthesis.
Which has a lower ΔGºOxidation, methane or carbon dioxide?
Methane, as more possibility to release energy through oxidation.
Is glucose or fatty acids a more efficient fuel? Why?
Fatty acids are a more efficient fuel, as they are reduced more and can be oxidised much further than glucose.
Where do electrons lost in metabolism go?
To NAD and FAD carriers.
When are NAD and FAD oxidised? What happens?
At electron transport chain.
Causes H+ to be pumped out of mitochondria.
What forms ATP in final stage of fuel catabolism with influx of H+? Where?
Oxidative phosphorylation. Mitochondria (eukaryotes).
What happens after final stage of ETC?
Electrons fed to O2, combining with H+ to form H20.
Broadly speaking, what happens in the first stage of catabolism?
Complex C fuels (fats, polysaccharides, proteins) degraded into smaller units.
Broadly speaking, what happens in the second stage of catabolism?
Convergence of small units into a few simple units. Acetyl CoA.
Broadly speaking, what happens in the third stage of catabolism?
Acetyl oxidised to CO2,
Reduction of NAD+ and FAD,
Generation of H+ gradient and synthesis of ATP.
