MCB Exam 4
An energy carrier that accepts electrons and feeds them into the electron transport chain
flavin adenine dinucleotide (FAD)
- glucose is metabolized to pyruvate in 10 linked reactions. Under anaerobic conditions, pyruvate is metabolized to lactate and, under aerobic conditions, to acetyl CoA. The glucose-derived carbons of acetyl CoA are subsequently oxidized to CO2 The process by which cells commonly obtain energy by breaking the chemical bonds of glucose molecules and use this energy to form ATP
glucose metabolism
Processes that obtain, release, and use energy
intermediary metabolism
6 seconds - atp stores in muscles is used first 10 seconds - atp is formed when creatnine phosphate and ADP (direct phosphrylation) 30/40 sec - end of exercise - glycogen stores in muscles is broken down to glucose, which is oxidized to generate ATP (anaerobic pathway)
short-duration exercise
The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism.
substrate-level phosphorylation
The formation of ATP by directly transferring a phosphate group to ADP from an intermediate substrate in catabolism.
substrate-level phosphorylation
protons
Which one of the following flows down its concentration gradient in order to power an ATP-synthesizing enzyme?
musclle and fat cels
GLUT4 transporters are found in:
liver
Glucokinase is found in:
pyruvate
Glucose can be metabolized in 10 steps to _____, which can then be processed further either aerobically or anaerobically.
1) molecules are degraded or synthesized stepwise in a series of reactions termed metabolic pathways 2) ATP is the energy currency of life. 3) ATP can be formed by the oxidation of carbon fuels 4) Although, many reactions occur inside a cell, a limited number of reaction types that involve intermediates are common to all metabolic pathways. 5) Metabolic pathways are highly regulated 6) The enzymes involved in metabolism are organized into large complexes
6 basic principles govern energy manipulations in all cells
amino acids
Glucose is an essential fuel for the brain. In times of starvation, glucose is generated from non-diet precursors. As skeletal muscle breaks down, _____ is/are generated and enter the gluconeogenic pathway to generate fuel for the brain.
unstable; stable
A key property of phosphate esters is that they are thermodynamically _____ and kinetically _____.
two; pyruvate; two
Glycolysis is the sequence of reactions that metabolizes one molecule of glucose to _____ molecule(s) of _____ resulting in the net production of _____ molecule(s) of ATP.
K; subdermal hemorrhaging
A deficiency in vitamin _____ can lead to _____.
zero
How many flavin moieties does NADH contain?
0
How many niacin moieties does FADH2 contain?
e is the natural log.
A reaction's equilibrium constant and change in free energy under standard conditions are related by a log function. More specifically, the log function is in base _____.
cleavage of either of its two phosphoanhydride bonds proceeds with a large negative delta G of bydrolysis
ATP has a high phosphoryl group transfer potential because:
recycling the ADP by phosphorylating it to generate another ATP molecule.
After an ATP molecule is used, the primary means of generating another ATP molecule is BEST described as _____.
no vitamin b serves as a coenzyme though
Are Vitamins A, C, D, E and K coenzymes?
oxidizing organic fuels and use it to make ATP
Catabolic pathways yield energy by
intermediate metabolism
Catabolism and Anabolism are considered to be _____________.
breakdown of macromolecules into smaller molecules
Catbolism
acyl
CoA is an important carrier of _____ groups in metabolism.
A coenzyme that carries acetate from the link reaction of respiration to Krebs cycle. a coenzyme, a small molecule required for enzymatic activity, present in all cells; necessary for cell respiration and fatty-acid metabolism
Coenzyme A
the amount of a particular enzyme depends on both its rate of synthesis and its rate of degradation. the level of many enzymes is adjusted by a change in the rate of transcription of the genes encoding them - rate of synthesis - rate of degradation
Controlling the amounts of enzymes
catalytic activity is regulated allosterically or by covalent modification. allosteric control = rapid. hormones coordinate metabolic relations between different tissues, often by regulating the reversible modification of key enzymes - allosteric control - reversible covalent modification - hormonal control
Controlling the catalytic activity of enzymes`
can regenerate aTP from ADP, allowing a short burst of activity s in a sprint. once the creatine phosphate stores are depleted, ATP must be generated by metabolic pathways
Creatnine Phosphate
carbon dioxide
In carbohydrate catabolism, which one of the following best indicates the carbon-containing oxidation product?
one; O2
During the metabolic oxidation of fuel molecules, the oxidation takes place _____ carbon(s) at a time, with the electrons passed to _____.
1. Oxidoreductases 2. Transferases 3. Hydrolases 4. Lyases 5. Isomerases 6. Ligases
Enzyme classes
releases energy
Exergonic
slowly; slowly
For metabolism to be efficient, it is important that an electron carrier like NADH react _____ with oxygen in the absence of a catalyst, and that ATP be hydrolyzed _____ in the absence of a catalyst.
large molecules; smaller units
In the first stage of generating energy from foodstuffs, _____ in food are broken down into _____ in the process of digestion.
vitamins
Many activated carriers are derived from
catabolic
Metabolic reactions that release energy are called _____ reactions.
`A recurring theme, subject or idea
Motif
coenzymes that carry activated electrons derived from the oxidation of fuels electron carriers that are oxidized
NAD+ and FAD are
an activated carrier of electrons for reductive biosynthesis
NADP+
- Each nucleotide added to a growing DNA strand comes from a nucleoside triphosphate, which is a nucleoside (a sugar and a base) with three phosphate groups - dATP, the nucleoside triphosphate that supplies an adenine nucleotide to DNA - Nucleoside triphosphates used for DNA synthesis are chemically reactive, partly because their triphosphate tails have an unstable cluster of negative charge - As each monomer joins the growing end of a DNA strand, two phosphate groups are lost as a molecule of pyrophosphate - Subsequent hydrolysis of the pyrophosphate to two molecules of inorganic phosphate is a coupled exergonic reaction that helps drive the polymerization reaction
Nuceloside Triphosphates
formation of ion gradients
Oxidation of carbon fuels is linked to ATP formation by the _____.
The standard free energy of hydrolysis A means of comparing the tendency of organic molecules to transfer a phosphoryl group to an acceptor molecule ex: ATP
Phosphoryl-transfer potential
obtain energy by capturing sunlight
Phototrophs
pyruvate
Some amino acids can enter the gluconeogenic pathway at the level of:
coenzymes normally after some chemical modification
The B vitamin function as..
acetaldehyde
The enzyme pyruvate decarboxylase in yeast produces what product?
glycolysis
When glucose is abundant, the predominant pathway in mammals will be:
the more free energy is released upon oxidation
The more reduced a carbon atom is...
-13.8 kJ mol-1
The phosphorylation of glucose has a ΔG°′ of +16.7 kJ mol-1. Glucose + Pi ⇌ glucose 6-phosphate What would be the ΔG°′ of the reaction if coupled to the hydrolysis of ATP? ATP + H2O → ADP + Pi ΔG°′ = -30.5 kJ mol-1
ATP
The universal currency of free energy in biological systems is _____.
citrate
Which of the following CANNOT be transformed to glucose via gluconeogenesis?
skeletal produces liver
Under normal conditions, what type of muscle produces lactate and where is it converted back to pyruvate?
They are both thermodynamically favorable; the rate for each reaction will depend on whether a catalyst is present.
Under standard conditions, is it more likely that ATP will be hydrolyzed to ADP or that acetyl CoA will be hydrolyzed to acetate and CoA?
1) Muscle contraction 2) Active trasnport 3) biosynthesis
What are the 3 fundamental needs energy is required to meet?
Digestion: [ endogenous: lipolysis, glycogenolysis, protein degradation exogenous: specific hydrolases] Generation of key metabolic intermediates: [ fatty acid and degradation and glycolysis & pyruvate dehydrogenase complex] Complete oxidation the citric acid cycle, electron transport chain, and oxidative phosphorylation
What are the 3 stages of generation of energy from food?
1. large molecules in food are broken down into smaller molecules in the process of digestion 2. the many small molecules are processed into key molecules of metabolism 3. ATP is produced from the complete oxidation of key molecules such as acetyl CoA
What are the 3 stages that chemotrophs obtain energy? (3 stages of generation of energy from food)
1. the individual reactions must be specific 2. the pathway in total must be thermodynamically favorable
What are the criterias in order to construct a metabolic pathway?
Compounds with higher standard free energies of phosphorylated compounds than ATP: 1. phosphoenolpyruvate (PEP) 2. 1,3- diphosphoglycerate 3. Creatnine phosphate
What are the other compounds with higher phosphoryl transfer potential?
metabolic pathways must be ablw to create = homoeostasis = STABLE BIOCHEMICAL ENVIRONMENT Homeostasis is maintained by 3 crucial regulatory strategies: 1. controlling the amount of enzymes 2. controlling catalytic activity 3. controlling the accessibility of substrates
What are the three principle ways metabolic processes are regulated?
- extract chemical energy from substances obtained from the external environment - form and degrade the biomolecules of the cell - convert exogenous foodstuffs into building blocks and precursors of macromolecules - assemble the building-block molecules into macromolecules
What function is a purpose of metabolism?
smaller amino acids being linked together to make a protein
What is an example of anabolic pathway?
equilibrate extracellular substances and the biomolecules of the cell
What is not a purpose of metabolism?
-1
What is the net charge on a hydride ion?
dna synthesis rna synthesis
What processes use phosphodiester bond formation?
vitamin B2 This is riboflavin, which makes FAD.
What vitamin is mixed with ADP to make FAD?
methane
Which of the following has the largest negative ΔG°′oxidation?
pyruvate
Which of the following is NOT a potential ending point for fermentation?
to alter the conformation of a protein
Which of the following is a way that phosphoryl transfer can be used in a biological organism?
Mg2+
Which of the following is required for the biologically active form of ATP?
Alcoholic fermentation produces CO2, while lactic acid fermentation produces no CO2.
Which of the following is true for alcohol fermentation but not true of lactic acid fermentation?
riboflavin (vitamin B2)
Which of the following vitamins is a precursor to a coenzyme that carries out oxidation-reduction reactions?
an oxidation
Which one of the following best describes a reaction that creates a carbon-carbon double bond, converting a —CH2—CH2— to a —CH=CH—?
All organisms use and make ATP. Even phototrophs use and make ATP.
Which one of the following types of organisms does not use or make ATP?
1. resonance stabilization [orthophosphate (Pi) has greater resonance stabilization than ATP] 2. electrostatic repulsion [repulsion between phosphates is reduced when ATP is hydrolyzed] 3. increase in entropy [entropy of the products of ATP is hydrolysis is greater: 2 products instead of 1] 4. stabilization due to hydration [water binds to ADP and Pi, stabilizing these molecules]
Why does ATP have a high phosphoryl-transfer potential?
1. activated carrier of phosphoryl groups: ATP 2. activated carriers of electrons for fuel electrons for fuel oxidation: NADH/NAD+ and FADH2/FAD 3. an activated carrier of electrons for reductive biosynthesis: NADPH/NADP+ 4. An activated carrier of 2 carbon fragments: coenzyme A ___________________________________________________________ 2 characteristics are common to activated carriers: 1. the carriers are kinetically stable in the absence of specific catalysts. 2. the metabolism of activated groups in accomplished with a small number of carriers
activated carriers exemplify the modular design and economy of metabolism
metabolic pathways that have both catabolic and anabolic functions
amphibolic pathways
use ATP and reducing power to synthesize large biomolecules
anabolic pathways
Useful energy + simple precursors -- (anabolism) --> complex molecules Glycogen synthesis: glucose to glycogen Gluconeogenesis: glucose from non carbohydrate precursors Triacylglycerol synthesis: fatty acids & glycerol to triacylglycerol Fatty acid synthesis: acetyl CoA to fatty acids
anabolism process and what it needs
acyl phosphayrylation
carbon oxidation of GAP generates an..
combust carbon fuels to synthesize ATP or ion gradients
catabolic pathways
Fuel (carbohydrates, fats) -- (catbolism)-> CO2 + H2O + useful energy Glycogenolysis : glycogen breakdown to glucose Glycolysis: glucose to pyruvate Pyruvate dehydrogenase: pyruvate to acetyl CoA Lipolysis: triacylglycerol to fatty acids & glycerol Fatty acid degradation: fatty acids to acetyl CoA
catabolism process and what it needs
obtain energy through the oxidation of carbon fuels
chemotrophs
opposing reactions, such as fatty acid synthesis and degradation, may occur in different cellular compartments. compartmentalization segregates opposed reactions. controlling the flux of substrates between compartments is used to regulate metabolism .
controlling the accessibility of substrates
the energy status of the cell is often an important regulator of enzyme activity 2 common means are used to assess energy status: - energy charge - phosphorylation potential
enzyme activity is often regulated by energy statis
Produced outside the body
exogenous
1. activated carriers exemplify the modular design and economy of metabolism 2. key reactions are reiterated throughout metabolism 3. metabolic processes are regulated in 3 principle ways 4. the enzymes involved in metabolism are organized into large complexes.
metabolic pathways contain many recurring motifs.
An energy carrier that accepts electrons and feeds them into the electron transport chain
nicotinamide adenine dinucleotide (NAD+)
ATP + NDP --> NTP + ADP
nucleoside diphosphate kinase
ATP + NMP --> ADP + NDP
nucleoside monophosphate kinase
ion gradients can couple endergonic reactions with exergonic reactions. in animals 90% of ATP is generated when the energy of a proton gradient is coupled with ATP synthesis in the process of oxidative phosphorylation The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.
oxidative phosphorylation
multienzyme complexes increase catalytic efficiency by making it easier for one product to become a reactant of another reaction, as well as aid in coordinated regulation
the enzymes involved in metabolism are organized into large complexes
exergonic [bc the triphosphate unit contains 2 phosphoanhydride bonds that are unstable ATP + H2O -> ADP + Pi (-G) ATP + H2O -> AMP + Pi
the hydrolysis of ATP is highly..
exergonic b/c thioester is unstable
the transfer of the acyl group is highly..
1. kinetically stable in absence of specific catalysts 2. the metabolism of activated groups is accomplished w a SMALL # of carriers
what are characteristics of activated carriers?
1. oxidation-reduction : e- transfer 2. group transfer: transfer of a functional group from one molecule to another 3. Hydrolytic : cleavage of bonds by the addition of water 4. carbon bond cleavage by means other than hydrolysis or oxidation : two substrates yielding one product or vice versa. when h2O or CO2 are a product, a double bond is formed 5. isomerization: rearrangement of atoms to form isomers 6. ligation requiring ATP cleavage : formation of covalent.bonds (i.e: carbon-carbon bonds)
what are the types of chemical reactions in metabolism
NADH is primarily used for ATP generation (in NAD form) NADPH is primarily used for biosynthesis [presence of P is the anabolic tag]
what best characterizes NADH and NADPH?
- enzyme compartmentalization (separate opposing pathways - so they not active at the same time as other ones) - action of hormones (glucagon insulon) - covalent modification of an enzyme (mostly phosphorylation) - regulation of enzyme activity (mostly at the level of allosteric control and lowkey level of covalent modification which is c
what can be used as a metabolic control mechanism?
adenosine triphosphate (ATP) oxidation of food molecules [primarily carbohydrates and fats] is transformed into ATP which acts as the energy free donor in most energy requiring processes such as motion, active transport, and biosynthetic reactions.
what is the universal currency of free energy?
tRNA charging ubiquitin activation
what processes use adenylation?
