Metabolism: Gibb's Free Energy Flashcards
Catabolic reactions
Breaking down reactions/molecules
What do catabolic reactions provide?
Building blocks necessary for anabolic reactions (amino acids, nucleic acids, fatty acids, vitamins, C HOPKINS CaFe)
Electrons
What is the purpose of electrons in catabolic reactions?
A source of energy for the synthesis of ATP
Anabolic reactions
Building up reactions
Gibbs free energy equation
Delta G = Delta H - (T*Delta S)
Delta G
Gibb’s free energy, a measure of the spontaneity of a reaction
What does a - Delta G mean?
Spontaneous, energy-yielding reaction (exergonic)
What does a + Delta G mean?
Non-spontaneous, energy-requiring reaction (endergonic)
Delta H
Enthalpy, a measure of the energy content of a substance
What does a - Delta H mean?
Heat releasing, exothermic reaction
What does a + Delta H mean?
Heat absorbing, endothermic reaction
Delta S
Entropy, a measure of the order of a substance
What does a - Delta S mean?
Decreased disorder, increased order
What does a + Delta S mean?
Increased disorder, decreased order (preferred)
The second law of thermodynamics
In every physical and chemical reaction, the universe always tends toward greater disorder; adds direction to every reaction
What does the second law of thermodynamics require for an endergonic reaction?
That endergonic reaction be coupled with a greater exergonic reaction to proceed
What is the most abundant organic molecule in the biosphere?
Glucose
What uses glycolytic pathways to obtain energy and carbon?
Chemoorganoheterotrophs
What is the most common glycolytic pathway?
Embden-Meyerhof-Parnas Pathway (EMP)
What is the overall reaction in the EMP Pathway?
Glucose + 2ADP + 2Pi + 2NAD+ –>
2 pyruvate + 2 ATP + 2NADH + 2H+
EMP pathway is not only for glucose
Other carbohydrates can be converted to various intermediates in the pathway and shunted in
What are the other molecules that the EMP pathway can use?
Galactose, Fructose, Mannose, Glycerol
What is the main objective of EMP Pathway
Partial oxidation of substrates, produces little ATP and NADH and prepares carbon (pyruvate) for entry into the Citric Acid Cycle/ Kelvin Cycle
What are the enzymes involved in the EMP Pathway?
Hexokinase (EC 2): Transferase
Glucose-6-phosphate Isomerase (EC 5): Isomerase
Phosphofructokinase (EC 2): Transferase
Aldolase (EC 4): Lyase
Triosephosphate Isomerase (EC 5): Isomerase
Glyceraldehyde-3-phosphate dehydrogenase (EC 1):
Oxidoreductase
Phosphoglycerate kinase (EC 2): transferase
Phosphoglycerate mutase (EC 5): Isomerase
Enolase (EC 4): Lyase
Pyruvate kinase (EC 2): transferase
What is the less common glycolytic pathway?
Entner-Doudoroff Pathway
What bacteria use the EDP pathway?
When they are restricted to this pathway as they are missing one or more of the enzymes required by the EMP pathway
Can organisms use both the EDP pathway and the EMP pathway?
Yes some archaea can switch between both pathways
What can not be used in the EMP pathway?
Carbohydrates so they are shunted in as 6-phosphogluconate or 2-keto-3-deoxy-6-phosphogluconate
What is the overall reaction of the EDP Pathway
Glucose + NADP+ + NAD+ + ADP + Pi –> 2 pyruvate + NADPH + 2H+ + NADH + ATP
What uses the EDP Pathway?
Obligate aerobes
Why do only obligate aerobes use the EDP Pathway?
Aerobes are not impaired by the lower ATP levels generated
Most ATP is generated in the electron transport chain
What does “Pentose” refer to in the Pentose Phosphate Pathway
The production of 5-carbon intermediates
What Pathway does the PP Pathway work with?
EMP Pathway
What is the primary purpose of the Pentose Phosphate Pathway?
Generate NADPH and precursors for biosynthesis (anabolism)
Enzymes?
Ribonucleotides
Deoxyribonucleotides
Aromatic amino acids (W, Y, F)
Other aromatic metabolites
Proteases
Break down proteins to peptides
Peptidases
Break down peptides to amino acids
Deaminases
Remove the amino group
What does EC stand for?
Enzyme commission number
EC 1
Oxidoreductases: transfer electrons from one molecule to another molecule
EC 2
Transferases: transfer a functional group from one molecule to another molecule (PO4, OH, CH3)
EC 3
Hydrolases: break covalent bonds using a molecule of water (have water in the equation/reaction)
EC 4
Lyases: break covalent bonds without water