Energy and Metabolism Flashcards
where does energy come from?
nutrients are necessary in order to produce energy in the human body
what are the laws of thermodynamics?
energy can neither be created or destroyed but it is transferred from one form to another or from one place to another.
what is metabolism?
the sum of all chemical reactions in which energy is made available and consumed in the body. basically oxidation of food to CO2 and H20
what are some examples of why the body needs energy?
-contraction of muscle
-generation of heat maintenance
what is Gibbs free energy?
-if product has more energy than the substrate it is G positive
-if the product has less energy than the substrate it is G negative
what does exergonic mean?
when the Gibbs free energy of the products is smaller than the reactants (gibbs negative)
what happens when reactions are exergonic?
the cells can harass this extra energy as ATP
can ATP move around the body?
no it can’t move through the body from one tissue to another.
what is ATP
-adenine
-ribose
-phosphate groups (held together by phospho and ribose bones which are very strong so when broken release lots of energy)
how is ADP released from ATP?
ATP binds with water and creates an inorganic phosphate and ADP along with energy (50kj)
what is the TCA cycle?
-acetyl CoA condenses with oxaloacetate to produce citrate. only produces one ATP
what are the 2 stages of the TCA cycle?
-decarboxylating (citrate to 4 carbon succinyl CoA. 2 carbon lost in the form of CO2)
-reductive (succinyl CoA to oxalocaetate)
what is the electron transport chain?
highly exagonic process, uses lots of energy. role is pump protons across inner mitochondrial membrane to inter membrane space. vast majority of ATP made
for one molecule of acetyl coA what do we get?
-reduction of 3 molecules of NAD+ to NADH
-reduction of one molecule of FAD to FADH2
what are the steps of ETC?
-NADH delivers electrons to first proteins
-electrons move along and make energy
-this energy is used to pump hydrogen ions across the inner membrane from the matrix to the inter membrane space.
-high conc of hydrogen ions in intermemebrane space
-oxygen accepts the electrons to make water
-ATP synthase makes a channel which allows hydrogen ions flow out of the inter membrane space along conc gradient
-ATP synthase spins and creates ATP
how much ATP is yield?
-1 in the GTP (substrate level phosphorylation)
-one NADH yields 2.5 ATP and each FADH2 yields 1.5 ATP in the ETC
thus total yield for one CoA is 10 ATP
what is glycolysis?
the breakdown of six carbon glucose molecule to 2 3 carbon pyruvate molecules. occurs in the cytosol in cells and can occur in all cells (shortage of oxygen and no mitochondria) some energy is required for the first phase.
what is the 1st phase?
energy investment phase, needs glucose and requires 2 ATP
what is the 2nd phase?
where we get payback and more molecules. 2 molecules of NADH and 4 ATP
what happens under anaerobic conditions?
-pyruvate is converted to lactacte.
-this regenerates NAD+ (oxidised form) to keep glycolysis going.
overall equation is
glucose +2ADP +2P -> 2 lactate 2 ATP
what happens under aerobic conditions?
pyruvate is transported into the mitochondrion and converted to acetyl coA by the action of pyruvate dehydrogenase
-overall equation is
CH3-CO-CO2 + NAD+ + CoASH -> CH3-CO-SCoA + CO2 + NADH
what is fatty acid metabolism?
-fatty acid and glycerol are released from triglyceride stores in adipose tissue via the action of lipase enzymes
-fatty acids are transported in the blood as a complex with albumin (because they’re hydrophobic) and are taken up by cells for oxidation
-fatty acid modification and entry into mitochondria
-beta oxidation (break down of fatty acid to ATP) leading to ATP formation
what does the breakdown of fatty acids consist of?
-modified by addition of Co enzyme A in the presence of acetyl coA synthesise (requires 2 ATP)
how does it cross the inner mitochondrial membrane?
carnitine shuttle
-co enzyme A present on fatty acid is removed and replaced with carnitine
-this gives fatty ACyL carnitine
-can now enter through a specialised transport protein
-once it enters the matrix the carnitine is removed
what is beta oxidation?
-cleaves the carbon backbone between the alpha and beta carbons so they are proximal to this carboxyl terminus. you get a break in this section which forms acetyl co A
-has to take place 7 times to produce 8 co enzymes A
what is yielded from one beta oxidation reaction?
-one NADH
-one FADH2
-can go directly to ETC
how does protein metabolism take place?
2 steps;
-transamination
-deamination
what is transamination?
removes amine group and transfers it to a keto acid. when it accepts this it in turn donates its ketone residue to the original amino acid.
what is deamination?
the removal of this amine group, takes place in the liver. ammonia is removed from the body and released in urine. releases the carbon backbone of the amino acid which then can be regenerated to glucose, fatty acids or various Krebs cycle intermediates.
what are glucogenic?
-make glucose
-pyruvate
-oxaloacetate
-intermediate of TCA
what are ketogenic?
make fatty acids
-acetyl CoA
-acetoacetyl CoA
where does metabolic fuel come from in prolonged periods of starvation?
fat- triacylglycerols in adipose tissue which is sufficient to prolong life for 3 months
protein - provides approx 14 days worth of energy but is spared as long as possible to permit mobility
what is fatigue?
overwhelming sense of tiredness, lack of energy and exhaustion
what is the BMR?
basal metabolic rate, represents the energy required to maintain basic function
what are the major causes of fatigue?
-phosphocreatine depletion
-phosphocreatine depletion and proton accumulation
-proton accumulation
-glycogen depletion
under aerobic condition what stage of cellular respiration makes the most ATP?
oxidative phosphorylation
