biochem bioenergetics Flashcards
the sum of a l chemical reactions involved in maintaining the dynamic state of a cell or organism.
metabolism
a series of biochemical reactions.
pathway
the biochemical pathways that are involved in generating energy by breaking down large nutrient molecules into sma ler molecules with the concurrent production of energy.
catabolism
the pathways by which biomolecules are synthesized.
anabolism
is the sum of catabolism and anabolism
metabolism
where replication of DNA takes place
nucleus
remove damaged cellular components and some unwanted foreign materials
lysosomes
package and process proteins for secretion and delivery to other cellular components.
golgi bodies
organeles in which the common catabolic pathway takes place in higher organisms; the purpose of this catabolic pathway is to convert the energy stored in food molecules into energy stored in molecules of ATP.
mitochondria
electron transport chain & phosphorylation together is called
oxidative phosphorylation
also ca led the tricarboxylic acid (TCA) or Krebs cycle.
citric acid cycle
_______&_______ together is called
oxidative phosphorylation
- Four principal compounds participating in the common catabolic pathway are:
- AMP, ADP, and ATP
- NAD+/NADH
- FAD/FADH2
- coenzyme A; abbreviated CoA or CoA-SH
is the most important compound involved in the transfer of phosphate groups.
ATP
- ATP contains
two phosphoric anhydride bonds and one phosphoric ester bond
- Hydrolysis of the terminal phosphate
anhydride
- Hydrolysis of the terminal phosphate (anhydride) of ATP gives
ADP, phosphate ion, and energy
- Hydrolysis of a phosphoric anhydride ____________than hydrolysis of a phosphoric ester.
liberates more energy
- We say that ATP and ADP contain
two high-energy phosphoric anhydride bonds.
is a universal carrier of phosphate groups
- ATP
is also a common currency for the storage and transfer of energy
ATP
is a biological oxidizing agent
nicotine adenine dinucleotide
The plus sign on NAD+ represents the
positive charge on this nitrogen
is a two-electron oxidizing agent, and is reduced to NADH.
- NAD+
is a two-electron reducing agent, and is oxidized to NAD+.
- NADH
is an electron and hydrogen ion transporting molecule.
- NADH
is a two-electron oxidizing agent, and is reduced to FADH2.
- FAD
is a two-electron reducing agent, and is oxidized to FAD.
- FADH2
is an acetyl-carrying group.
coenzyme A (CoA)
Like NAD+ and FAD, coenzyme A contains
a unit of ADP
- The vitamin part of coenzyme A is
pantothenic acid.
- The acetyl group of acetyl CoA is bound as a
high-energy thioester.
- The high-energy thioester of acetyl CoA is hydrolyzed.
step 1
- Citrate synthase, an a losteric enzyme, is inhibited by
NADH, ATP, and succinyl-CoA
dehydration and rehydration, catalyzed by aconitase, gives isocitrate.
Step 2:
- _____ and _____ are achiral; neither has a stereocenter.
Citrate and aconitate
is chiral; it has 2 stereocenters and 4 stereoisomers are possible
- Isocitrate is chiral; it has__ stereocenters and___stereoisomers are possible.
2
4
oxidation of isocitrate fo lowed by decarboxylation gives a-ketoglutarate.
- Step 3
is an a losteric enzyme; it is inhibited by ATP and NADH, and activated by ADP and NAD+.
- Isocitrate dehydrogenase
oxidative decarboxylation of a-ketoglutarate to succinyl-CoA.
- Step 4:
formation of succinate.
- Step 5:
- This is the first, and only, energy-yielding step of the cycle; a molecule of GTP is produced.
- Step 5
- The two CH2-COO- groups of succinate are now equivalent.
- Step 5
oxidation of succinate to fumarate.
Step 6:
hydration of fumarate to L-malate.
Step 7
is chiral and can exist as a pair of enantiomers; It is produced in the cycle as a single stereoisomer.
- Malate
: oxidation of malate.
- Step 8
- Oxaloacetate now can react with acetyl CoA to start another round of the cycle by repeating Step 1.
- Step 8
- Controlled by three feedback mechanisms
citric acid cycle
inhibited by ATP, NADH, and succinyl CoA; also product inhibition by citrate.
citrate synthase
activated by ADP and NAD+, inhibited by ATP and NADH
isocitrate dehydrogenase
inhibited by ATP, NADH, and succinyl CoA; activated by ADP and NAD+.
ketoglutarate dehydrogenase complex
- Carried out by four closely related multi subunit membrane-bound complexes and two electron carriers, coenzyme Q and cytochrome c.
oxidative phosphorylation
- O2 is reduced to H2O
oxidative phosphorylation
- This large complex contains some 40 subunits, among them are a flavoprotein, several iron-sulfur (FeS) clusters, and coenzyme Q (CoQ, ubiquinone).
complex 1
- Complex I oxidizes _____ to ____
NADH to NAD+.
- The oxidizing agent is CoQ, which is reduced to
CoQH2.
oxidizes FADH2 to FAD.
- Complex II
delivers electrons from CoQH2 to cytochrome c (Cyt c).
- Complex III
- Complex IV is also known as
cytochrome oxidase
- Complex IV It contains ___ subunits,
13
- electrons flow from Cyt c (oxidized) in _______to Cyt a3 in _______
Complex III
Complex IV
- From Cyt a3 electrons are transferred to
O2.
- During this redox reaction, H+ are pumped from the matrix into the
intermembrane space.
- Summing the reactions of Complexes I - IV, six H+ are pumped out per NADH and four H+ per FADH2.
- The energy-releasing oxidations give rise to proton pumping and a ________ is created across the inner mitochondrial membrane.
ph gradient
- There is a _______ of H+ in the intermembrane space than inside the mitochondria.
higher concentration
- This proton gradient provides the driving force to propel protons back into the mitochondrion through the enzyme complex called
proton translocating ATPase
- The overa l reactions of oxidative phosphorylation are:
NADH + 3ADP +
1 O2 + 3P + H+ NAD+ + 3ATP + H O
2 i 2
FADH2 + 2ADP +
1 O2 + 2Pi FAD + 2ATP + H2O
- Protons flow back into the matrix through channels in the
F0 unit of ATP synthase.
- Oxidation of each NADH gives
3ATP.
- Oxidation of each FADH2 gives
2 ATP
- Thus, the yield of ATP per two-carbon acetyl group oxidized to CO2 is:
3 NADH x
1 FADH2 x
3 ATP NADH
2 ATP
FADH2
= 9 ATP
= 2 ATP
1 GTP = 1 ATP
= 12 ATP
- The chemical energy of ATP is converted by the body to several other forms of energy:
electrical energy
mechanical energy
heat energy
- It also maintains a Na+ concentration gradient across cell membranes
lower inside, higher outside.
- The body maintains a K+ concentration gradient across cell membranes;
higher inside and lower outside.
- This pumping requires energy, which is supplied by the hydrolysis of
ATP to ADP.
the chemical energy of ATP is transformed into ___________, which operates in neurotransmission.
electrical energy
- ATP drives the alternating association and dissociation of actin and myosin and, consequently, the contraction and relaxation of muscle tissue.
mechanical energy
- Hydrolysis of ATP to ADP yields 7.3 kcal/mol.
- Some of this energy is released as heat to maintain body temperature.
heat energy
