WEEK 13 (Metabolism) Flashcards
What are enzymes of Metabolic pathways able to do?
They are able to capture the energy contained in CARBOHYDRATES, PROTEINS and FATTY ACIDS in small portions and store it in the form of INTERNAL HIGH ENERGY COMPOUNDS such as ATP which drastically reduces the amount of energy lost as heat
What are the properties of ATP?
- Source of immediate usable energy
- Adenine-containing RNA nucleotide with three phosphate groups
Why is ATP called a high-energy phosphate compound?
ΔG0 (Gibbs free energy) of hydrolysis is around -7.3 kcal/mol for each of the two terminal phosphate groups. Because of the large negative ΔG0 of hydrolysis, ATP is called a high-energy phosphate compound.
How many naturally occurring amino acids form proteins?
20
What is the difference between the Lock-and-Key model and the Induced-fit model?
LOCK-AND-KEY MODEL: the enzyme binding site is an exact match for the substrates
INDUCED-FIT MODEL: the enzyme binds most tightly to an intermediate form of substrate or product. The model is more compatible with reversible reactions that are catalysed by one enzyme
What is the mechanism behind enzyme action?
1) Enzyme binds with substrate forming an enzyme-substrate complex
2) Product is formed at a lower activation energy
3) Product is released
What is the difference between Anabolic and Catabolic?
Anabolism refers to the process which builds molecules the body needs; it usually requires energy for completion. Catabolism refers to the process that breaks down complex molecules into smaller molecules; it usually releases energy for the organism to use
What is Feedback Inhibition?
When the final product of a pathway controls the rate of its own synthesis through inhibition of its first step
Why is the Feedback Inhibition mechanism necessary?
Because it is the only way it can avoid wasting energy making end-products that are already in plenty
How does Enzyme inhibition work?
1) An inhibitor fixes itself to the active site of the enzyme and prevents the substrate from binding which stalls the sequence of the metabolic pathway (A CONFORMATIONAL CHANGE)
2) Binding is temporary so as soon as the inhibitor disengages, the enzyme goes back to its active shape and continues to work on this substrate, opening up the pathway once again
3) Homeostasis is maintained with respect to the amount of end product that is produced
Where is the uptake energy stored in the products of Anabolic reactions?
In the C-C bond of larger molecules
What are the major anabolic pathways?
- Photosynthesis
- Pentose phosphate pathway
- Gluconeogenesis
- Protein biosynthesis
- Fatty acid synthesis
- Glycogenesis
Energy stored in which bonds will get released in Catabolic reactions?
Covalent bonds (e.g C-C)
Can catabolic pathways also operate on energy storing molecules like lipids and glycogen to release energy and make ATP?
YES
What are the major catabolic pathways?
- Glycolysis
- Kreb’s cycle
- Oxidative phosphorylation
- Beta oxidation of fatty acid
- Urea cycle
- Glycogenolysis
