Energy Reactions In Cells Pt 1 Flashcards
What is metabolism ?
Metabolism is a set of pathways that derive energy and raw materials from food stuff to use them to support repair, growth and activity of the tissues of the body to sustain life.
What occurs in catabolic pathways?
- Break down of larger molecules into smaller ones (intermediary metabolites)
- releases a large amount of free energy
- oxidative - reduces H atoms - reducing power
What occurs in anabolic pathways?
- Synthesis of larger important cellular components from intermediary metabolites
- Uses energy released from catabolism (ATP)
- reductive - uses H released in catabolism
Why are fuel molecules metabolised?
To Supply
- Building block materials(sugars, amino acids and fatty acids).
- Dynamic state of cell components (turnover)
- Cell growth and division
- Repair - Organic precursors (Acetyl CoA)
- allow for inter conversion of building block materials - Biosynthetic reducing power (NADH, NADPH)
- Energy for Cell function (ATP)
What type of energy is used in Biology?
- Chemical bond energy is predominantly used to drive energy requiring activities
- used directly without conversion to heat
- man is isothermal - can not use heat energy for work
What occurs in an exergonic reaction?
- Release energy
- Only reaction that occurs spontaneously as the products are at a lower energy level than the substrates and some energy is released during the reaction.
- negative change in free energy (delta G)
What are the key point in exergonic and endergonic reactions?
- Exergonic reaction
- Delta (triangle) G is less than 0
- Reaction is spontaneous
- Energy levels of products is lower than energy level of reactants - Endergonic reaction
- Delta G is more than 0
- Reaction is not spontaneous
- Requires energy input
- Energy level of products is higher than reactants
What conditions required for standard free energy change ?
- kjoule.mole-1
- kcal.mole-1
Delta G nought : 25 degrees, 1 atmosphere pressure, 1 molar concentration of reactants and products (not really happening as our metabolism is working in milimolar)
Delta G nought prime: pH = 7
What is the formula for non-standard conditions ?
Pg 20
- Delta G indicates whether reaction is spontaneous, does not indicate rate.
What is oxidation?
- Chemical bond energy in a fuel molecule is released by oxidation reactions.
- oxidation is the removal of electrons (e-) or removal or H-atoms (H+ + e-)
What is a redox reaction?
- All oxidation reactions accompanied by a reduction reaction is known as a redox reaction.
OIL RIG = oxidation is loss of e-, reduction is a gain
What happens when fuel molecules are oxidised? And What are the major carrier molecules and information on them?
- Electrons and protons are transferred carrier molecules.
Oxidised and then reduced forms -
NAD+ NADH + H+
NADP+ NADPH + H+
FAD FADH2
- Total concentration of oxidised and reduced carriers are constant.
- Therefore, must be a cycle between oxidative processes and reductive processes
- Act as carriers of reducing power for
a) ATP production (NADH + H+)
b) Biosynthesis (NADPH)
What are the key concepts about H-carrier molecules?
- Complex molecules - contains components from vitamins (B vitamins)
- Converted to reduced forms by adding 2 H atoms (H+ + e-)
- H+ dissociates into solution
- For structure in NAD(P)+and NAD(P)H - one hydrogen binds to the nicotinamide group and one is released/lost into solution
- in FAD both H atoms bing to the flavin part
How can energy released during oxidative metabolism be used?
- Energy released from food by oxidation - exergonic
- Energy released as reducing equivalents can be used to drive energy requiring activities through coupling systems.
- Directly e.g. use of NADPH in biosynthesis
- Indirectly e.g. mitochondrial system to couple NADH and FADH2 to the production of an intermediate ‘energy currency’ molecule - ATP
What is the H-carrier redox cycles?
Pg 27
