Metabolism Flashcards
*Understand the three stages of food oxidation.
3 stages of food oxidation:
- Large molecules in food are broken down into smaller molecules in process of digestion (preparation stage)
(ex: fats broken to fatty acids, glycogen; proteins to amino acids, polysaccharides to glucose and other sugars). - The many small molecules are processed into key molecules of metabolism, most notably acetyl COA (Some atp here)
- ATP is produced from the complete oxidation of the acetyl from acetyl COA
*Have an appreciation for the central role played by acetyl CoA.
Acetyl COA- activated two-carbon unit that is the fuel for final stages of aerobic metabolism.
Acetyl COA brings the breakdown products of proteins, carbs, lipids into the citric acid cycle to be oxidized to CO2.
*Understand the terms anabolic, catabolic and amphibolic.
Metabolic pathways have two types:
1. Catabolic- combust fuels to synthesize ATP (fuels break down to Co2, H2O and energy.
2. Anabolic- use ATP and reducing power to make synthesize large biomolecules (energy and simple precursors form complex molecules)
Amphibolic pathways- can function anabolically or catabolically.
although anabolic and catabolic pathways have reaction in common, the regulated irreversible reactions are always distinct.
*Biosynthetic and degradative pathways often have reactions in common, the regulated
irreversible reactions of each pathway are largely distinct, have general understanding as
to why this is so.
The regulated, irreversible reactions of the pathways are irreversible since it helps control metabolism.
also, the irreversible reactions are distinct so that both pathways (catabolic, anabolic) will not happen at the same time and you can drive reaction forward. ?????
- Understand the distinction between anaerobic and aerobic metabolism.
anaerobic metabolism- process where you create energy through combustion of carbs in ABSENCE of OXYGEN.
aerobic metabolism- create energy in PRESENCE of OXYGEN, through combustion of carbs, fats, amino acids.
*Understand coupled reactions in terms of ΔG and the idea that free-energy changes are
additive.
A reaction takes place spontaneously only if delta G (change in free energy) is negative. the overall free-energy change for a chemically coupled series of reactions is equal to the sum of the free-energy changes of the individual steps. hence, since free energy changes are additive, a thermodynamically unfavorable reaction can be driven by a favorable reaction coupled to it
*Understand the role of ATP in metabolic reactions.
energy derived from fuels or light is converted into adenosine triphosphate (ATP), which is cellular energy currency.
ATP acts as the free-energy donor in most energy-requiring processes such as motion, active transport, or biosynthesis.
A large amount of free energy is liberated when ATP is hydrolyzed to ADP and pi and AMP and ppi.
ATP drives reactions that require an input of free energy, such as muscle contraction.
Unfavorable reaction like endergonic ones (delta g is positve) can be made possible by coupling ATP hydrolysis, which changes equilibrium by 100,000 fold.
*What is creatine phosphate?
Creatine phosphate- high phosphoryl transfer potential molecule in muscle that serves as a reservoir of high potential phosphoryl groups.
Creatine phosphate can regenerate ATP from ADP, allowing a short burst of activity as in a sprint.
muscle contains only enough ATP to power muscle contraction for less than a second.
once the creatine phosphate stores are depleted, ATP must be generated by metabolic pathways (anaerobic and aerobic).
creatine phosphate and ADP (through creatine kinase) forms ATP and creatine.
*Understand the concepts of oxidation and reduction and why these reactions are coupled.
Are fats or glucose more energy efficient?
Oxidation reactions involve loss of electrons, and these reactions must be coupled with reactions tat gain electrons.
The paired reactions are called oxidation-reduction reactions or redox reactions
The carbon atoms in fuels are oxidized to yield CO2, and the electrons are ultimately accepted by oxygen to form H2O.
the more reduced a carbon atom is, the more free energy is released upon oxidation.
fats are more efficient food sources than glucose because fats are more reduced.
*What are activated carriers of electrons?
Activated carriers of electrons are Nicotinamide adenine dinucleotide (NAD+) and Flavin adenine dinucleotide (FAD) which carry activated electrons derived from oxidation of fuels.
NAD can accept 2 electrons, take up 1 H
FAD can accept 2 electrons, take up 2 H’s
*Understand the three principle ways metabolism is regulated.
Homeostasis- stable biochemical environment that is maintained by careful regulation of chemical processes.
metabolism regulated by three ways:
1. The amount of enzyme present (gene expression)
2. The catalytic activity of enzymes (Allosteric regulation, covalent modification
3. The accessibility of substrates.
Which two processes do cells get the most ATP from?
The citric acid cycle and oxidative phosphorylation.
Describe the main reasons why energy is required, and discuss the different sources of how energy is obtained.
Energy is required to power:
1. muscle contraction and movement of cells
2. active transport of molecules and ions
3. biosynthesis of cellular components.
Energy sources:
phototrophs (plants) obtain energy by capturing sunlight
chemotrophs (humans) obtain energy though oxidation of carbon fuels.
What are the basic principles that govern energy manipulations in all cells?
- molecules are degraded or synthesized stepwise in a series of reactions termed metabolic pathways
- ATP is energy currency of life.
- ATP can be formed through oxidation of fuels.
- although many reactions occur inside the cell, there are limited number of reaction types involving particular intermediates common to all metabolic pathways.
- metabolic pathways are highly regulated.
What is metabolism?
Metabolism is a series of linked reactions that convert a specific reactant into a specific product.
entire set of cellular metabolic reactions are called INTERMEDIARY METABOLISM.
