Metabolism Flashcards
(19 cards)
Define anabolism
Anabolic processes involve the synthesis of larger, more complex molecules from simpler ones
- requires energy
- Builds macromolecules like proteins, nucleic acids, lipids, and carbohydrates
Examples of anabolism
Protein synthesis from amino acids.
DNA synthesis from nucleotides.
Glycogen synthesis from glucose
Define Catabolism
Catabolic processes involve the breakdown of complex molecules into simpler ones, releasing energy in the process
- releases energy
- Involves the degradation of macromolecules to smaller units
Examples of catabolism
Glycolysis (breakdown of glucose).
Lipolysis (breakdown of fats).
Protein degradation into amino acids.
Why are metabolic pathways interconnected?
Efficiency, energy transfer, flexibility, compartmentalization, and regulation of feedback mechanisms
which two main strategies do cells use to carry out individual endergonic reactions with a positive ΔG…
- Coupling with Exergonic Reactions to drive reactions forward
- Alteration of Reaction Conditions to shift equilibrium
Explain ATP as the energy currency (reactive coupling)
Adenosine triphosphate (ATP) is the primary energy carrier molecule used by cells to power endergonic reactions due to the large amount of energy released when its phosphate bonds are broken.
Explain Enzymes facilitate coupling:
Enzymes play a crucial role in linking exergonic and endergonic reactions by bringing reactants together in a favorable orientation to facilitate the transfer of energy
Why hydrolysis of ATP releases a lot of energy?
Hydrolysis of ATP releases a large amount of energy because the bonds connecting the phosphate groups in ATP are considered “high-energy bonds” due to the electrostatic repulsion between their negative charges,
- electrostatic repulsion
- resonance stabilization
- increased entropy
Compounds with High Phosphoryl Transfer Potential
Compounds that readily donate phosphate groups to ADP or other substrates due to their inherent instability or high energy:
- ADP
- Phosphoenolpyruvate (PEP)
- 1,3-Bisphosphoglycerate (1,3-BPG)
Compounds with Low Phosphoryl Transfer Potential
Compounds that do not readily donate phosphate groups and are generally more stable:
- Glucose-6-phosphate
- ADP
Define coenzymes and examples
Coenzymes are organic molecules that transiently associate with enzymes and are essential for their activity. They often act as carriers for specific atoms or functional groups during the reaction
- NAD+
- FAD
- CoA
Often derived from vitamins that bind loosely to the enzyme and participate directly in the chemical reaction by transferring functional groups.
Define metal ions and examples
Metal ions can act as cofactors by providing structural stability to enzymes or participating directly in the catalytic process.
- Iron, Magnesium, Zinc
Metal ions can be tightly or loosely bound to enzymes, and their presence can enhance enzymatic activity or stabilize structures.
Define Prosthetic Groups and examples
Prosthetic groups are non-polypeptide entities that are permanently attached to an enzyme and are integral to its function.
- Heme
- Flavin
Unlike coenzymes, prosthetic groups are not released after the reaction; they remain bound to the enzyme and play a continuous role in its activity.
Define feedback regulation
Feedback regulation involves the modulation of an enzyme’s activity based on the concentration of end products. It is a common form of regulation in metabolic pathways.
Define the negative feedback mechanism
When the end product of a pathway accumulates, it can inhibit an upstream enzyme, thereby reducing the pathway’s activity. This prevents overproduction of the product.
Define the accessibility of substrates
The availability of substrates can influence the rate of enzymatic reactions in metabolic pathways.
If substrates are abundant, enzymes can catalyze reactions more readily, increasing the flux through the pathway. Conversely, if substrates are scarce, the reaction rate will decrease.
Define expression of enzyme genes
The regulation of gene expression that encodes enzymes can have long-term effects on the levels of metabolic enzymes available for catalysis.
Describe how metabolic pathways are generally regulated
feedback inhibition, where the end product of a pathway inhibits an earlier enzyme in the pathway, effectively controlling the rate of production when the product is already present in sufficient quantities.
