Physio Test 1 Ch3

anabolic

oxidation-reduction reactions

oxidation

The chemical reaction catalyzed by a protein kinase is an endergonic reaction.

true

1.The (E (change in energy) is negative. + 2.The reaction does not occur spontaneously. 3.Reactants have less energy than products. 4.Energy must be added.

Anabolic reactions are able to occur in cells because cellular mechanisms link these reactions with catabolic reactions.

is an endergonic reaction

anabolism and condensation

As this reaction proceeds to the right, its rate of sucrose production will decline.

when the reactant is converted to product at the same rate that product is converted to reactant

the difference in energy between the reactants and products

1.temperature 2.height of the activation energy barrier 3.reactant and product concentration 4.transition state ++

coenzyme D

Enzymes increase the rate of reactions by decreasing the amount of energy needed for the colliding reactant molecules to enter into a transitional state.

an enzyme with high affinity for substrate

Allosteric activators increase enzyme reaction rates by binding to the active site of the enzyme molecule.

PFK is an allosteric enzyme that is inhibited by ATP and stimulated by AMP.

oxidative phosphorylation

the potential energy of the transition state is greater than that of either of the reactants or products

two pyruvate

glycogenolysis

beta oxidation

the ATP synthesis that occurs at the inner mitochondrial membrane

40

glycolysis

linking step; 0 ATP synthesized per molecule of glucose

Before glycogen can be used in glycolysis, it is first broken down into glucose molecules.

metabolism

oxidation

hydrolysis

glycogenesis

The sum of all chemical reactions occurring in the body. These reactions take place in the cells of all organ systems

the study of energy transfer in biological systems

Synthesis - energy must be put into the reactions

Breakdown - energy is given off when the reactions occur

Energy can not be created or destroyed, but is transformed from one form to another without being depleted.

Illustrated as body transforms chemical energy in food to heat and ATP, which serves as the exclusive chemical to power biological work

All of the energy of the Universe will inevitable be degraded to heat and the organization of matter will become totally randomized Entropy (randomness) of a closed system will progressively increase and the amount of energy capable of performing work will diminish. Thus, a nonrandom system (entropy low) contains potential energy by virtue of its orderliness - in becoming disordered (increase in entropy) energy is released and work may be performed

As entropy increases, potential energy decreases, i.e., energy available to do work decreases

Proceeds spontaneously because it obeys 2nd Law (Entropy ?) spontaneous because change in free energy is negative. which means reactants have more energy than products. catabolic

Does not proceed spontaneously. Needs added energy source to go nonspontaneous because change in free energy is positive. which means products have more energy than reactants. anabolic

Exergonic reaction will not proceed until activation energy barrier is overcome. So, a little bit if energy must be put into an exergonic reaction before it can proceed spontaneously. The coupled reaction A + C ? B + D will occur if 2 conditions are met - activation energy barrier overcome and energy released A ? B is greater than energy required for C ? D.

having no apparent external cause or influence; occurring or produced by its own energy, force, etc. or through internal causes; self-acting

Alter the Activation Energy Barrier

Enzymes are proteins that bind to reactants (substrates) and act as catalysts to speed the rate of product formation

Enzymes are specific for one set of substrates or a group of similar substrates -2 Models of Substrate Specificity ---Lock and Key model and Induced-fit model (next) Enzymes are not changed in the reaction Enzymes are not consumed in the reaction Almost all Enzymes are identified by the suffix -ase

Enzyme's catalytic rate: how fast reactants (substrates) are consumed and products generated ---Main factors affecting catalytic rate are: Substrate concentration - ?S will ? chance of ES binding Enzyme concentration - ?E will ?ES binding and ?max rate of S?P Affinity of enzyme for substrate - affected by activators and inhibitors for selected (allosteric) enzymes Temperature and pH (temp increase faster rate)

Allosteric enzymes have an active site and one or more regulatory sites where modulators (activators and inhibitors) bind

phosphate group.

kinase-moving a phosphate

Cofactors -Trace metals: Mg, Cu, Zn, Fe Allow the substrate to bind to the active site (modulation by magnesium on right Coenzymes: Organic molecules that participate in a reaction catalyzed by an enzyme. Typically transfer an atom or small chemical groups Vitamins, such as NAD and FAD that we will see in action soon

K=products/reactants

ATP is the only chemical that can be directly used to power biological work. Several metabolic pathways coordinate to keep ATP concentration constant at all times and under all conditions. Variation in speed, capacity, and location

Creatine kinase reaction - fastest, smallest capacity. Regulated by Law of Mass Action. Location: Cytosol. Very important in muscle metabolism. Minor pathway in most organs Glycolysis - next fastest, limited capacity. Cytosol Aerobic glucose oxidation - pretty fast, decent capacity. Mitochondria Fatty acid oxidation - considerably slower than above, unlimited capacity. Mitochondria Protein oxidation - very, very slow; big capacity, but lethal if overused. Mitochondria (mostly) & cytosol

Energy from exergonic reactions is used to synthesize adenosine triphosphate (ATP) 2 types of ATP synthesis reactions Substrate-level phosphorylation. Does not involve O2 X-P + ADP--> X + ATP Ex. - Creatine kinase Oxidative phosphorylation: requires electron transport chain & O2 ADP + Pi--> ATP

the fastest ATP producing pathway in the body. It's reversible and obeys Law of Mass Action

an important regulator of enzyme activity in metabolic pathways. Low initial concentration of ADP and its huge relative increase make it one of the most important stimulators of enzymes involved in ATP production. ATP itself is much less important in regulating its own production.

Glycolysis -- cytosol Krebs cycle -- mitochondria matrix Electron transport chain -- inner mitochondria mem. Oxidative phosphorylation -- mitochondria

Key players (enzymes and carriers): 1. Hexokinase 2. Phosphofructokinase (PFK) 3. Glyceraldehyde-3-phosphate dehydrogenase (G3PD) 4. Lactate dehydrogenase (LDH) 5. NADH shuttle from cytosol to mitochondria

Key players: 1. Pyruvate dehydrogenase (PDH) 2. Citric acid - 2 3C molecules at top of citric acid (Krebs) cycle 3. Citric acid (Krebs) cycle 4. Cytochrome oxidase and rest of electron transport chain 5. Oxidative phosphorylation

Breakdown of glucose to two pyruvate molecules(2 3C molecues). Sequence of 10 enzyme-catalyzed reactions that take place in the cytosol. Net gain of 2 ATP molecules 2 NAD+ molecules reduced to 2 NADH molecules No O2 consumed (anaerobic), no CO2 produced

All enzymes except PFK (3) are reversible. For almost all physiological conditions, HK is irreversible.

Glucose enters tissues from the blood and is phosphorylated by HK. This traps it in the cell. Added phosphate group will eventually return to ATP. G6P will enter glycolysis immediately or be added to glycogen and stored for later use.

muscle (mostly), liver, and kidney (very little)

Liver and kidney, but not muscle, have G-6-phosphatase to dephosphorylate G-6-phosphate so glucose can leave their cells.

Provide glucose to other cells as needed and keep blood glucose constant

Endogonic - energy put in PFK controls it. Only allosteric enzyme in glycolysis. Modulators: ADP & AMP activate; citric acid inhibits

Exergonic (spontaneous)- energy released

Note - the two molecules are different when first split, but both become glyceraldehyde-3-phosphate almost immediately - Pi is attached to #3 carbon

GLY- keep NAD level high and NADH level low Mito- opposite

This addition must be removed before NAD is ready to be used again, but the normal mechanisms for this type of reaction are found in the mitochondria. This is a problem, because glycolysis occurs in the cytoplasm, and NAD and NADH cannot enter the mitochondria. The body overcomes this difficulty by using glycerol phosphate, a molecule that can pass across the mitochondrial membranes. In fermentation, the hydrogen is instead removed when NADH helps convert pyruvic acid to lactic acid.

In (a) the H is removed and transported into a mitochondria where it is reattached to NAD from the mitochondria pool of NAD forming a new NADH. Mitochondrial NADH provides energy to synthesize 3 ATP molecules. Pyruvate will not be converted to lactate, but enters mitochondria too where it is used to synthesize many ATPs. Almost always the choice under resting aerobic conditions. In (b) NAD is regenerated when pyruvate is converted to lactate by lactate dehydrogenase (LDH) reaction. No ATP synthesized, but glycolysis can keep going. Only option when O2 concentration is too low for aerobic energy pathways in mitochondria to work. Which energy producing pathways can work under anaerobic conditions? Even when O2 is abundant, some lactate produced. When rate of NADH generation exceeds capacity of option (a), more lactate is produced even when high O2 is present.

It's released into blood. Lactate buildup lowers pH and is toxic to cell. Most handled by Cori cycle

pyruvate enters mitochondrion-- PDH complex

mitochondrial matrix

citric acid cycle, begins with Citrate synthase, high levels inhibit PFK

acetyl CoA + 3 NAD+ + FAD + ADP + Pi + 3 H2O--> 2 CO2 + 3 NADH + 3 H+ + FADH2 + ATP + CoA

Energy from NADH & FADH2 transferred to electrochemical gradient, which is then transferred to ATP when ATP Synthase is stimulated to open by elevated ADP concentration. ATP synthase allows only H+ to pass through its open pore - operates similar to mechanical box and is another example of the breakdown products of ATP stimulating its synthesis. 1?2 O2 required by both NADH and FADH2, but less ATP produced by FADH2 because of where it enters the chain. NADH = 3 ATP / 1?2 O2; FADH2 = 2 ATP / 1?2 O2.

10 NADH + 10 H+ + 2 FADH2 + 34 ADP + 34 Pi + 6O2 ---> 10 NAD+ + 2 FAD + 12 H2O + 34 ATP

C6H12O6 + 6O2 = 6CO2 + 38 ATP C16H32O2 + 23O2 = 16CO2 + 130 ATP Lots of ATP from fat, but all of it comes from aerobic pathways inside mitochondria. Cannot synthesize ATP in cytosol w/fats. if there's a 16 C fat, there will be 16 CO2 molecules in it.

Because they form many acetylCoA molecules Lots of AcetylCoA also means lots of citrate (Krebs cycle), which can signal glycolysis to slow down (PFK inhibition) because it is not needed as much. Saves those precious carbohydrates when fat is able to provide more of the energy.

?-oxidation. A 5 enzyme pathway located in the mitochondria matrix.