Chapter 15 Metabolism:Basic Concepts and Design Flashcards
What is the first stage of generation of energy from food?
Large molecules in food are broken down into smaller molecules in the process of digestion
What is the second stage of generation of energy from food?
The many small molecules are processed into key molecules of metabolism, most notably acetyl CoA
What is the third stage of generation of energy from food?
ATP is produced from the complete oxidation of acetyl CoA
Energy is required to meet what three fundamental needs?
1.To do work: power muscle contraction, cell movement
2.Active transport
3.Biosynthesis
What is a Phototroph?
Something that obtains energy by capturing sunlight
What is a Chemotroph?
Something that obtains energy through the oxidation of carbon fuels.
What are metabolic pathways
This is when molecules are degraded or synthesized stepwise in a series of reactions
How can ATP be formed?
By oxidation of carbon fuels
What is a metabolism?
It is a series of linked reactions that convert a specific reactant into specific product
What do the Catabolic pathways do?
They combust carbon fuels to synthesize ATP or ion gradients
What do Anabolic pathways do?
They use ATP and reducing power to synthesize large biomolecules
In order to construct a metabolic pathway, what two criteria must be met?
1.The individual reactions must be specific
2.The pathway in total must be thermodynamically favorable
What do Heterotrophs do?
They extract the chemical potential energy stored in sugars and other organic compounds and release CO2 and H2O
The hydrolysis of ATP is ___________ because the triphosphate unit contains ___________________________________ that are unstable
Exergonic, Two Phosphoanyhdride bonds, unstable
What is the Phosphoryl-transfer potential?
This is the means of comparing the tendency of organic molecules to transfer a phosphoric group to an acceptor molecule
What factors cause ATP to have a high phosphoryl-transfer potential
1.Charge repulsion
2.Resonance Stabilization
3.Increase in entropy
4.Law of Mass Action
5.Stabilization by hydration
Phosphate esters are thermodynamically ______, yet they are kinetically _________
unstable, stable
Why are phosphate esters stable?
Because the inherent negative charges resist hydrolysis
What other roles do ATP have ?
ATP can function as a biological hydrotrope and it can also play a role in maintaining protein solubility
What is the immediate donor of free energy for biological activities
ATP
Why are fats more efficient food source than glucose?
Because fats are more reduced
As prominent fuels, Why do we use carbs more than fatty acids when FAs store my energy
Its because carbs are biological more available compared to fatty acids
The oxidation of the carbon atom may form a compound with high phosphoryl transfer potential to later form what?
ATP
What two characteristics are common to activated carriers?
- The carriers are kinetically stable in the absence of specific catalysts
- The metabolism of activated groups is accomplished with a small number of carriers
What do NAD+ and FAD carry?
They carry activated electrons derived from the oxidation of fuels.
In the structure of NAD+ which H is the reactive site and in the standard form what charge does N have?
Top right H of the hexagon is the reactive site and the N has a positive charge.
In the structure of FAD what Ns are the reactive site?
in the three hexagons in a line the bottom right N and the N at the very top are reactive sites
The transfer of the acyl group is _____________ because the thioester is ___________
Exergonic,unstable
In the structure of CoA what is the reactive site ?
The HS on the left of the CoA is the reactive site
What is more stable the oxygen esters or Acyl CoA and why?
Its because oxygen esters are more stable because they are stabilized by resonance structure.
What do B vitamins function as?
Coenzyme
Metabolic processes are regulated in which three ways?
1.The amount of enzymes present
2. The catalytic activity of enzymes
3. The accessibility of substrates
