Intro to metabolism (wk2) Flashcards
Define metabolism and its processes
(metabolism, reacts, basic principles)
-Metabolism = The sum of a series of chemical reactions or The sum of the chemical reactions occurring in a living organism or part of it
-The reactions are termed metabolic reactions, and the compounds that participate in them are referred to as metabolites.
-All reactions are: governed by the principles of mass conservation, reversible, complex – bit often form linked pathways
-Basic principles of metabolism -> Hydrolysis of Urea is a reversible chemical reaction. These factors are subject to chemical thermodynamics – energy changes in chemical systems and are applied to living organisms (through bioenergetic pathways)
Free energy change in chemical reactions
+draw the equation
-In cells, chemical reactions take place between products and reactants with different energy content. The change in free energy is names after the chemist Josiah Willard Gibbs.
Free energy change in chemical reactions
(enthalpy, entropy (S), entropy (S) in a biological field
-Enthalpy -> It is bond energy (how much energy is stored by/in the molecules). The enthalpy H of reactants or of products is equal to their total bond energies. The overall change in enthalpy (∆H) is equal to the overall change in bond energies.
-Entropy (S) -> A measure/degree of randomness/disorder. The second law of thermodynamics states that the state of entropy of an isolated system, will always increase over time.
-Entropy (S) in a biological field -> Many biological reactions are not isolated, but linked to others and therefore can see increases in order (decreased S). For example, the reactions that link amino acids to form proteins. Solution of proteins has more order (lower entropy) than a solution of the same amino acids unlinked. For the linking reaction to proceed, a compensatory decrease in free energy must occur elsewhere in the system (in a linked reaction).
Free energy change in chemical reactions
(exergonic, endergonic, equilibrium)
-Free energy change provides a single criterion as to which way a reaction will go
-Exergonic -> free energy of products is lower than the reactants
-Endergonic -> free energy of products is higher than the reactants
-Equilibrium -> dynamic state whereby energy of products and reactants is equal
Calculating free energy change in biochemical reactions
+ draw the equation
-Calculating free energy change in biochemical reactions -> We can estimate free-energy changes for different temperatures and initial concentrations using the equation:
Where R is a gas constant, T is temperature, and Q is the initial ratio of molar concentrations of products to reactants. In biology, organisms can affect the outcome for a favourbale reaction by changing the available concentrations of products and reactants
Expressing standard free energy changes
-Expressing standard free energy changes -> Comparisons of free energy changes between different reactions provide context e.g. free energy derived from different biomolecules. The standard free-energy changes of a reaction is (∆G) (‘delta G nought prime’) is the value of the change in free energy under standard conditions (25 C, 1atm pressure, pH 7.0)
Expressing free energy changes in metabolism (kcal)
-Expressing free energy changes in metabolism (kcal) -> Energy (kcal) released for work. Free energy changes are expressed in kcal. 1kcal is the amount of energy required to raise the temperature of 1kg of water by 1 C. In exergonic reactions, the (∆G) will tell us how much energy is available for work.
-ATP carries a lot of free energy
-Work production is vital to a multitude of biological functions, such as muscle activity and transport of solutes. This importance is a reason why exergonic reactions are desirable (apart form being able to proceed spontaneously).
-∆G is defined as the free-energy change of the reaction when the concentration of every participating substance in solution is 1 mol L-1 (called the standard state).
Draw the hydrolysis of ATP for energy
Define and describe catabolism
+draw the equation
-Catabolism = A series of reactions that breaks down biomolecules into smaller molecules.
* Catabolism generates ATP by:
* ATP synthesis is endergonic, therefore unfavoured. Linking it to the catabolic reaction allows it to proceed:
Define and describe anabolism
+draw the equations
-Anabolism = Growth, cell division, energy storage
* Synthesis requires energy (endergonic), therefore unfavoured
* ATP hydrolysis can help:
* More ATP hydrolysis is still needed to generate:
Draw the phases of metabolism
ATPases
-Describe and draw the table
-ATPases -> Proteins catalysing the hydrolysis of ATP to liberate free energy for cellular ‘work’.
Redox reactions in metabolism
-Oxidation and reduction
-Oxidation and reduction > Metabolic reactions often involve oxidations and reductions of biological substances:
* When a compound accepts oxygen atoms, it is oxidised
* When a compound loses oxygen atoms, it is reduced
* When a compound loses hydrogen atoms, it is oxidised
* When a compound accepts hydrogen atoms, it is reduced
-Since no atoms are lost or gained, oxidation and reduction are in constant equilibrium i.e. when one substance is reduced, another is oxidised -therefore ‘redox’ reactions
Draw the redox reactions in metabolism + describe NAD, other redox compounds, and oxidants and reductants
-NAD -> AMP plus nicotinamide mononucleotide derived from the vitamin Niacin. NAD exists in oxidised and reduced forms. The oxidised form, NAD+ can accept a hydrogen form an oxidising metabolite, forming NADH (the reduced form).
-Other redox compounds that assist hydrogen transactions are : NADP+/ NADPH (Nicotinamide adenine dinucleotide phosphate) and FAD/FADH (Flavin adenine dinucleotide)
-Oxidants and reductants -> NAD+, NADP+ and FAD serve as oxidants by accepting H from metabolites. NADH, NADPH and FADH2 serve as reductants, donating H (electrons).
