Chapter 4: Energy/Metabolism Flashcards
what is energy?
the capacity to do work
Define kinetic energy.
the energy of motion
Define potential energy.
Stored energy
In what two ways is energy stored in the body?
- Concentration gradients
- Chemical Bonds
Define reactant.
substance or compound that is added to a system in order to bring about a chemical reaction
Define product.
Compounds formed during chemical reactions as reagents are consumed.
Define reactant rate.
the speed at which a reaction takes place
equal to the disappearance rate of reactants or appearance rate of products
Define exergonic
Releasing energy (usually as heat)
Define endergonic.
Requiring a net input of energy, which often remains trapped in chemical bonds formed via the reaction.
Define enzymes.
Proteins that speed up the rate of chemical reactions.
- they lower the activation energy for the reaction
Define substrate.
the reactants in enzymatically catalyzed reactions
Define coenzymes.
organic cofactors for enzymes
- they do not alter the binding sites of enzymes but rather act as receptors and carriers for atoms and functional groups removed from substrates
Define phosphorylation.
the addition of a phosphate group
ex: ADP becomes ATP
Define oxidation-reduction reaction.
Explain their metabolic significance.
the transfer of electrons from one molecule to another
they are important reactions in energy extraction and transfer in cells and occur throughout all three stages of respiration
If a molecule gains electrons, what is it said to be?
Reduced
If a molecule loses electrons, what is it said to be?
Oxidized
define metabolism
all chemical reactions that take place in an organism
define catabolism
reactions that release energy through the breakdown of large biomolecules
define anabolism
energy-utilizing reactions that result in the synthesis of large biomolecules
What are the three steps of cellular respiration?
- Glycolysis
- Krebs Cycle/Citric Acid Cycle/Keto Acid Cycle
- Electron Transport Chain
What are the major steps in glycolysis?
- 6-C glucose enters cell via facilitated diffusion
- 2 ATP are used to phosphorylate glucose into 1,6 - diphosphate fructose
- Sugar cleavage occurs, breaking 6-C, 2-P molecule into two separate C-C-C-P molecules
- each C-C-C-P molecule undergoes several reactions, producing 2 ATP and 1 NADH each for a total of 4 ATP and 2 NADH produced
- The end product is two C-C-C pyruvic acid molecules which continue on to the citric acid cycle
What is consumed and what is produced by glycolysis?
Consumed
- 1 glucose
- 2 ATP
Produced
- 2 NADH
- 4 ATP
- 1 H20
- 2 Pyruvate
What are the major steps of the citric acid cycle and intermediate step?
- the 2 pyruvates formed by glycolysis enter the mitochondrial matrix via double membrane
- in the intermediate step between glycolysis and the cycle, each pyruvate is oxidized, giving off a NADH and CO2 and gaining Coenzyme A to form Acetyl-CoA
- Acetyl-CoA enters the cycle, combines with 4-C product of previous cycle and forms 6-C citric acid
- 6-C citric acid is oxidized, gives off NADH and CO2, forms 5-C molecule
- **5-C is oxidized, gives off NADH and CO2, forms **4-C
- 4-C undergoes several reactions, forms 1 ATP, 1 FADH2, and 1 NADH, and continues to beginning of cycle, bonding with incoming acetyl-CoA
What is consumed and what is produced by the krebs cycle, including the intermediate step, for each pyruvate that goes into it?
Consumed
- 1 H20
Produced
- 4 NADH
- 1 FADH2
- 1 ATP
- 3 CO2
What are the major steps of the electron transport chain?
- NADH and FADH2 from C.A. cycle release H+ and e- into the intramembranal proteins of the ETC
- H+ is concentrated in the intermembranal space of the mitochondria
- Concentrated H+ flows back into the mitochondrial matrix via ATP Synthase, which it activates, creating ATP via oxidative phosphorylation
- H+ back in matrix combines with spent e- from the ETC and O2 to form H20
What is consumed and what is produced by the ETC and oxidative phosphorylation (per glucose molecule)?
Consumed:
- 10 NADH
- 2 FADH2
Produced:
- 28 ATP (10 NADH x 2.5 ATP + 2 FADH2 x 1.5 ATP)
- 6 H20
What is the overall reaction for respiration?
C6H12O6 + O2 ——> 6CO2 + 6 H2O + energy (ATP)
Compare substrate-level and oxidative phosphorylation.
Substrate-level phosphorylation:
- does not consume oxygen
- takes place in glycolysis and the kreb cycle
Oxidative phosphorylation:
- consumes oxygen
- takes plave in the ETC on the cristae membrane of mitochondria
How and where is ATP produced via glucose metabolism?
- in all three steps of respiration
How and where is ATP produced via lipid metabolism?
- triglycerides are broken down into glycerol and fatty acid chains by lipase
- 3-C glycerol molecules enter glycolysis at the same point where C-C-C-P molecules start after sugar cleavage
- F.A. chains are broken up in to 2-C fragments via beta oxidation and enter the Krebs cycle as C-C-CoA (Acetyl CoA)
( 15-16 ATP per glycerol, b/c it’s equal to half a glucose
each 2-C F.A. chain fragment runs through Krebs once, creating 3 NADH, 1 FADH2 and 1 ATP)
How and where is ATP produced via protein metabolism?
- liver removes amine group from fatty acids via oxidative deamination
- leftover multicarbon acid goes to respiration for ATP production
