Into to metabolism flashcards
Metabolism
Sum of all chemical reactions that occur in a cell, tissue, or the body. Process is heavily regulated and every reaction is catalyzed by enzymes.
Catabolic
Break down fuel molecules
Anabolic
Build molecules to produce fuel. Glucose, fatty acids, and some amino acids can be produced.
Exergonic reaction
delta G < 0 and proceeds towards equilibrium (spontaneous). Make ATP, NADH, and NADPH
Endergonic reaction
delta G > 0 and energy is needed for it to occur (not spontaneous). Use ATP and NADPH
Equation for delta G
delta G = delta H - T (delta S)
NADH
Intermediate which can be oxidized in terminal oxidation to produce ATP
5 reasons to use ATP
- Stores energy in high-energy chemical bonds 2. Links energy producing and energy using systems (universal free energy currency) 3. Chemical energy in ATP can be turned into other energies (chemical, mechanical, heat) 4. Acts as a second substrate (like in kinases/phosphatases) 5. May act as an allosteric effector (change conformation of protein to turn pathway on or off)
Energy-rich molecules
ATP, CTP, GTP, NADPH, NADH, UTP, Acetyl CoA and succinyl CoA (TCA cycle) , 1,3-biphosphoglycerate and phosphoenolpyruvate (glycolysis)
Anaplerotic reactions
Amino acids can join up in the pathway anywhere and fill in missing intermediates
What is the only energy-generating path in the cytosol?
Glycolysis utilizing glucose which is an anaerobic process
How do brain cells get fatty acid nutrients?
Ketone bodies produced in the liver which can pass the blood-brain barrier
How does the presence of mitochondria and oxygen affect types of fuel molecules which can be used in cells?
All cells use glucose through glycolysis to make energy (oxygen and mitochondria are not required). Need both mitochondria and oxygen to use glucose, fatty acids, and amino acids in the citric acid cycle.
Stepwise degredation of nutrients (3)
- Take up and digest nutrient macromolecules 2. Building blocks further degraded 3. Energy generated to yield ATP
4 major energy-generating reactions in the mitochondria
- Pyruvate dehydrogenase complex (PDH) 2. Fatty acid beta-oxidation 3. Krebs cycle (TCA) 4. Terminal oxidation (Electron transport + Oxidative phosphorylation) takes place in the mitochondrial inner membrane. All other reactions are in the mitosol (mitochondrial matrix)
Pyruvate dehydrogenase complex (PDH)
Mitochondrial complex of 3 enzymes which convert pyruvate into acetyl-CoA using pyruvate decarboxylation which is IRREVERSIBLE
Outer membrane of mitochondria
Simple membrane with a few enzymatic/transport functions. Permeable for most molecules.
Inner membrane of mitochondria
Complex with 80% protein content. Very selective permeability. Contains most of electron transport and oxidative phosphorylation enzymes, various dehydrogenases, and transport systems.
Mitochondiral DNA
Circular because of bacterial origin. Many disorders are related to the circular DNA. Passed down through mother.
2 ways for molecules to pass inner mitochondrial membrane
- Transporters 2. Shuttles
Transporters
Exchange ATP for ADP and Pi to move TCA intermediates in and out of mitochondrial membrane
Shuttles
Transport protons and electrons from NADH derived from glycolysis across inner mitochondrial membrane where they are oxidized
Atractyloside
Plant toxin which inhibits the adenine nucleotide transporter (exchanges ADP for ATP) on the inner mitochondrial membrane
Mersalyl
Mercury compound which inhibits the phosphate transporter on the inner mitochondrial membrane
Malate-aspartate and Alpha-glycerol phosphate shuttles
Irreversible transfer reducing of equivalents (protons and electrons) from cytosol to the mitosol where they are oxidized. Also reconstruct NAD+ to get back to cytosol so there is enough for glycolysis and other NAD+ requiring reactions.
