Energy and Metabolism Flashcards
what is the first law of thermodynamics
energy can neither be created nor destroyed but is transferred from one form to another or from one place or another
what is the second law of thermodynamics
energy doesn’t transform without entropy in the universe (usually lost as heat)
what is metabolism
the sum of all chemical reactions in which energy is made available and consumed in the body
examples of metabolism
oxidation of fuel to CO2 and water
- achieved by a series of biochemical reactions
production of energy (ATP) and loss of energy (heat)
what does the body need energy for
contraction of muscle
- skeletal, cardiac, smooth -> blood vessels and gut
accumulation of ions and other molecules against conc. gradients (nerve impulses)
biosynthesis -> building of tissues
waste disposal -> getting rid of the end products of bodily function
generation of heat -> maintenance of body temperature
reaction to create glucose 6 phosphate
glucose + PO4^2 –> glucose 6 phosphate
reaction cannot happen spontaneously because the energy of the products is higher than the sum of the energy of the reactants
in order for this equation to become spontaneous, we need to couple it with another equation
ATP -> ADP + PO4 2-
rules of gibbs free energy
if the product contains more energy than the substrate -> delta G is +ve
if the product contains less energy than the substrate -> delta G is -ve
is the catabolism of nutrients exergonic or endogonic?
exergonic
the cells can harness this energy as ATP
ATP basic info
energy currency of living organisms
- hydrolysis to give ADP and Pi liberates a large amount of energy
ATP equations
ATP (+ H2O) –> ADP + Pi
- delta G = -30kJ/mol
- in cells, delta G = -50kJ/mol
ADP + Pi –> ATP + H2O
- delta G = +30kJ/mol
- in cells +50 kJ/mol
endergonic definition
products of greater free energy than the reactants; non-spontaneous
free energy definition
the energy available in a system to do useful work
exergonic definition
reactants of greater free energy than the products; spontaneous
The tricarboxylic acid cycle (TCA)
also known as Krebs cycle
acetyl CoA (2 carbon) condenses with oxaloacetate (4 carbon) to produce citrate (6 carbon)
this occurs in 2 phases
- deoxycarbylation (citrate -> succinyl CoA (4 C )) -> 2 C molecules lost as CO2
- reductive (succinyl CoA to oxaloacetate)
what is the overall reaction for TCA
acetyl CoA + 3NAD+ + FAD + GDP + Pi + 2H2) –> CoA + 2CO2 + 3NADH + FADH2 + GTP (ATP) + 3H+
what are the products of 1 turn of TCA cycle
3 x NADH
1 x FADH2
^ molecules produce ATP in the ETC
what are the main components of the ETC
four protein complexes
ATP synthase
intermembrane space in mitochondria
FADH2
NADH
H+
co-enzyme Q
cytochrome C
progress of e- through the ETC
intermembrane has a higher conc. of protons because of pump
1- co-enzymes donate 2e- and H+ to the ETC
2- electrons passed through redox centre (in the complex)
- moved between redox centres
- each one has a higher affinity
- produces ATP (used to pump protons against conc. gradient)
3- co-enzyme Q passes the electrons to the next protein complex (1-> 2 -> 3)
4- cytochrome C -> complex 4
5- when e- reaches the end of complex 4
- 2H+ + 1/2O2 -> H2O
O2 is the terminal electron carrier
where does FADH2 enter the ETC
complex 2
what is oxidative phosphorylation
ATP synthase
- only way H+ can get back into matrix
- ADP + Pi -> ATP
- main generator of ATP