Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Biochem Ch. 15
Metabolism: basic concepts and design
| Question | Answer |
|---|---|
| Energy is required for what three things? | muscle contraction, cell movement, and biosynthesis |
| _________ obtain energy by capturing sunlight. | Phototrophs |
| __________ obtain energy through the oxidation of carbon fuels. | Chemotrophs |
| Basic Principles of Energy Flow: (1) How are molecules degraded or synthesized ? | stepwise in a series of reactions termed metabolic pathways |
| Basic Principles of Energy Flow: (2) ____ is the energy currency of life | ATP |
| Basic Principles of Energy Flow: (3) ATP can be formed by the __________ of carbon fuels. | oxidation |
| Basic Principles of Energy Flow: (4) although there are many metabolic pathways, a ________ number of types of reaction and particular intermediates are common to many pathways | limited |
| Basic Principles of Energy Flow: (5) Metabolic pathways are highly __________ | regulated |
| Metabolism | series of linked reactions that convert a specific reactant into a specific product. |
| The entire set of cellular metabolic reactions are called _____________ metabolism. | intermediary |
| Metabolic pathways can be divided into two groups based on whether they are energy-yielding reactions or energy-requiring reactions: | catabolic and anabolic |
| Catabolic pathways | combust carbon fuels to synthesize ATP |
| Anabolic pathways | use ATP and reducing power to synthesize large biomolecules |
| Some pathways, called ___________ pathways, can function anabolically or catabolically. | amphibolic |
| Although anabolic and catabolic pathways may have reactions in common, the regulated, irreversible reactions are always ________ | distinct |
| Ex) Glucose is metabolized to __________ in 10 linked reactions | pyruvate |
| Ex) pyruvate is metabolized to ________ under anaerobic conditions and is metabolized to _________ under aerobic conditions | lactate, acetyl CoA |
| In order to construct a metabolic pathway, two criteria must be met: | the individual reactions must be specific and the pathway in total, must be thermodynamically favorable |
| A thermodynamically unfavorable reaction can be driven. How? | by coupling it to a MORE favorable reaction so that the net reaction is thermodynamically favorable |
| Energy is derived from ______ or ______ is converted into adenosine triphosphate (ATP), the cellular energy currency | fuels or light is converted |
| ATP hydrolysis is exergonic. Why? | the ∆G (free energy content) of ATP is higher than the ∆G of ADP. (the triphosphate unit contains two phosphoanhydride bonds that are unstable) |
| The energy released on ATP hydrolysis is used for what? | to power a host of cellular functions |
| ATP Hydrolysis drives metabolism by shifting the equilibrium of couple reactions. Explain | unfavorable reactions can be made possible by coupling to ATP hydrolysis |
| What are the structures of ATP, ADP, and AMP? | These adenylates consist of adenine, a ribose, and a tri-, di-, or monophosphate unit |
| ATP is an efficient energy currency because of its __________- _________ potential | phosphoryl-transfer potential |
| Phosphoryl-transfer potential | the standard free energy of hydrolysis (means of comparing the tendency of org. molecules to transfer a phosphoryl group to an acceptor molecule) |
| Phosphoryl-transfer potential: The higher the value of ∆G value, the _________ the transfer potential | higher |
| ATP has a high phosphoryl-transfer potential because of what 4 key factors? | charge repulsion, resonance stabilization, stabilization by hydration, and an increase in entropy (1 ->3 pieces) |
| ATP has a phosphoryl-transfer potential that is ______________ among the biologically important phosphorylated molecules. And therefor has a central position in phosphoryl-transfer reactions. | intermediate |
| Central Position of ATP: High phosphoryl-transfer–potential compounds (1,3-BPG, PEP, and creatine phosphate) derived from the metabolism of fuel molecules are used to power what? | |
| Central Position of ATP: In turn, ATP ________ a phosphoryl group to other biomolecules to facilitate their metabolism. | donates |
| where does the energy used to regenerate ATP from ADP and Pi come from? | the carbon in fuel molecules (glucose and fats) is oxidized to CO2, and the energy released is used to regenerate ATP |
| Carbon oxidation is paired with a __________ | reduction |
| oxidation reactions involves the ______ of electrons, reduction reactions involves the ______ of electrons. The paired reactions are called ____________-____________ reactions | loss, gain, oxidation-reduction |
| The more ________ a carbon atom is, the more free energy is released upon oxidation | reduced |
| Why are fats a more efficient food source than glucose? | because fats are more reduced |
| The number of hydrogen atoms corresponds to how _________ a molecule is | reduced (fats have lots of hydrogens, very reduced) |
| If we oxidize a substrate, electrons are being lost. Where are the electrons going? | electrons are removed from carbon atoms and passed to O2 in a series of oxidation-reduction reactions |
| Compounds with _____ phosphoryl-transfer potential can couple carbon oxidation to ATP synthesis | high |
| Electrons flow down a stability gradient, a process that releases energy. Explain the flow of energy from carbon oxidation to ATP synthesis | The energy of carbon oxidation can be trapped as high-phosphoryl-transfer-potential compounds, which can then be used to power the synthesis of ATP. |
| Metabolism is characterized by common motifs: A small number of recurring activated _________, such as ATP, NADH, and acetyl CoA, transfer activated groups in many metabolic pathways | carriers |
| ATP is an activated carrier of ____________ groups | phosphoryl groups |
| Other activated carriers are common in biochemistry and are often derived from __________ | vitamins |
| Many of these activated carriers function as ____________, small organic molecules that serve as cofactors for enzymes | coenzymes |
| Nicotinamide adenine dinucleotide (NAD+) is a major ________ carrier in the oxidation of fuel molecules | electron |
| In the oxidation of a substrate, NAD+ accepts a hydrogen ion and two electrons, which are equivalent to what? | a hydride ion (H:-) |
| What is the reduced form of NAD+? | NADH |
| NAD+ + 2H+ + 2e- --> | NADH + H+ |
| The other major electron carrier in the oxidation of fuel molecules is the coenzyme ____ | FAD (flavin adenine dinucleotide) |
| FAD, like NAD+, can accept 2 electrons. How does FAD differ from NAD+? | when it accepts 2 electrons it also takes up 2 protons (NAD+ only takes 1 proton) |
| What is the reduced form of FAD? | FADH2 |
| FAD + 2H+ + 2e- --> | FADH2 |
| In most biosyntheses, the precursors are more oxidized than the products, hence reducing power is needed in addition to ATP. This process is called _____________ ______________ | reductive biosynthesis |
| ________, which carries two electrons at a high potential, provides reducing power in the biosynthesis of cell components from more oxidized precursors | NADPH |
| NADPH carries electrons in the same way as NADH. Then why is NADPH used exlusively for reductive biosynthesis and NADH is used primarily for the generation of ATP? | the extra phosphoryl group on NADPH is a tag that enables enzymes to distinguish between high-potential electrons to be used in anabolism and those to be used in catabolism |
| Coezyme A (CoA) is an activated carrier of what? | 2 carbon fragments: acetyl/acyl groups |
| Acyl groups are linked the sulfhydryl group of CoA by _________ bonds | thioester |
| The resulting derivative is called ________ CoA | acyl CoA |
| an acyl group is often linked to CoA is the acetyl unit. This derivative is called _______ CoA | acetyl CoA |
| Acetyl CoA + H2O <-> | acetate _ CoA + H+ |
| The hydrolysis of acetyl CoA is exergonic. Why? | the ∆G of the thioester is higher than the ∆G of the thiol. |
| Acetyl CoA has a _____ acetyl-group-transfer potential because transfer of the acetyl group is exergonic | high |
| NADH, NADPH, and FADH2 react slowly with oxygen in the absence of a catalyst. Likewise, ATP and acetyl CoA are hydrolyzed slowly in the absence of a catalyst. Why is the kinetic stability of these molecules in the absence of catalysts essential? | it enables enzymes to control the flow of free energy and reducing power |
| Regulation: The quantity of enzyme present can be regulated at the level of what? | gene transcription |
| Regulation: _________ activity is regulated allosterically or by covalent modification | Catalytic |
| Regulation: The energy status of the cell is often an important regulator of _________ activity | enzyme |
| What two common means are used to asses energy status? | energy charge and phosphorylation potential |
| energy charge = | [ATP] + 1/2[ADP] / [ATP]+[ADP]+[AMP] |
| Phosphorylation potential = | [ATP] / [ADP] + [Pi] |
Created by:
cmccartney2