Chap 15- Metabolism Flashcards
What is the first stage of generating energy from the oxidation of food?
Digestion: large molecules in food are broken down into smaller units.
What does digestion do?
Digestion renders the macromolecules in our meals into biochemically more manageable fragments.
In the digestion step, what is everything hydrolyzed to?
Proteins are hydrolyzed to the 20 amino acids, polysaccharides are hydrolyzed to simple sugars and fats are hydrolyzed to fatty acids. No useful energy is captured at this point.
What is the second stage in metabolism?
These numerous small molecules are degraded to a few simple units that play a central role in metabolism. Most of them, sugar, fatty acids, glycerol and amino acids, are converted into acetyl CoA.
What is generated during the second step of metabolism?
Some adenosine triphisohate (ATP) is generated, but the amount is small compared with that obtained in the third stage.
What happens during the third step of metabolism?
ATO is produced from the complete oxidation of acetyl CoA. The third stage consists of the citric acid cycle and oxidative phosphorylation, which are the final common pathways in the oxidation of fuel molecules.
What does acetyl CoA do in the third steel and what is made?
Acetyl CoA brings the breakdown products of proteins, sugars, and fats into the citric acid cycle, where they are completely oxidized to CO2.
Living organisms require a continual input of free energy for what three major purposes?
1) The performance of mechanical work in muscle contraction and cellular movements
2) the active transport of molecules and ions
3) the synthesis of macromolecules and other bio molecules from simple precursors
What are the differences between phototrophs and chemotrophs
Phototrophs are photosynthetic organisms that obtain energy by trapping sunlight ina chemical form. Chemotrophs, include humans, obtain energy through the oxidation of carbon fuels.
Principles that underlie energy flow in all living systems
1) Fuels are degraded and large molecules are constructed step by step in a series of linked reactions called metabolic pathways.
2) An energy currency common to all life forms, ATP , links energy-releasing pathways with energy-requiring pathways.
3. The oxidation of carbon fuels powers the formation of ATP.
4)Althouigh there are many metabolic pathways, a limited number of types of reactions and particular intermediates are common to many pathways
5) Metabolic pathways are highly regulated to allow the efficient use of fuels and to coordinate biosynthesis processes.
6) The enzymes involved in metabolism are organized into large complexes. The formation of metabolic enzymes into complexes increases efficiency by facilitating substrate and product movement between;the individual enzymes if the complex. ,
Metabolism def
Metabolism is a linked series of chemical reactions that begins with a particular bio molecule and converts it into some other required biomeolcule in a carefully defined fashion.
What do these metabolic pathways do to a bio molecule?
These metabolic pathways process a bio molecule from a starting point, glucose, to an end point (carbon dioxide, water, and biochemically useful energy, in regard to glucose) without the t generation of wasteful or harmful side products.
Intermediary metabolism def
Interdependent pathways - a biochemical ecosystem- and their activities are coordinated by exquisitely sensitive means of communication in which Allosteric enzymes are predominant
What are the broad classes of metabolic pathways?
1) Those that convert energy from fuels into biologically useful forms such as ATP or ion gradients.
2) Those that require inputs of energy to proceed
Catabolism def
Reactions that transform fuels into cellular energy.
Anabolism def
Those reactions that require energy- such as the synthesis of glucose, fats, or DNA.
Amphibolic pathways def
Pathways that be an be either anabolic or catabolic, depending on the energy conditions if the cell.
What is an important general principle of metabolism?
That although bio synthetic and degradation pathways often have reactions in common, the regulated, irreversible reactions of each pathway are almost always distinct from each other. This separation is necessary for energetic reasons, as will be evident in subsequent chapters. It also facilitates the control metabolism.
What criteria must a pathway satisfy?
1) the individual reactions must be specific
2) the entire set if reactions that constitute the pathway must be thermodynamically favoured.
A reaction that is specific will yield only one particular product or set of products from its reactants.
How can a thermodynamically unfavourable reaction be driven?
Can be driven by a thermodynamically favourable reaction to which it is coupled.
What is ATP?
ATP is a nucleotide consisting of adenine, a ribose, and a triphosphate unit. When looking at ATP as an energy carrier, we focus solely on the triphosphate moiety.
WHy is ATP an energy rich molecule?
Because its triphosphate unit contains two phosphoanhydride linkages, which are formed between two phosphoryl groups accompanied by the loss of water.
How can a thermodynamically unfavorable reaction sequence be converted into a favorable one?
A thermodynamically unfavorable reaction sequence can be converted into a favorable one by coupling it to the hydrolysis of ATP molecules in a new reaction.
What are the four factors that differentiate the stability of the reactants and products?
Electrostatic Repulsion
Resonance Stabilization
Increase in Entropy
Stabilization due to Hydration
