Nursing Biochemical Energy Production .pdf

Bio

1. BIOCHEMICAL ENERGY
PRODUCTIONS
JEMIMAH JOY I. GUARIN

2. METABOLISM
•Is the sum total of all the biochemical reactions that take place in a living organism.
•The simplest living cell is continually carrying on energy-demanding processes such as protein
synthesis, DNA replication, RNA transcription, and membrane transport.
Two Subtypes of Metabolic Reactions:
-Catabolism
-Anabolism

3. CATABOLISM VS. ANABOLISM
Catabolism
•is all metabolic reactions in which large biochemical molecules are broken down to smaller ones.
•A reactions usually release energy.
•E.g., reactions involved in the oxidation of glucose.
Anabolism
•Is all metabolic reactions in which small biochemical molecules are joined together to form larger
ones.
•These reactions usually require energy in order to proceed.
•E.g., the synthesis of proteins from amino acids.

4. METABOLIC PATHWAY
•Is a series of consecutive biochemical reactions used to convert a starting material into an
end product.
•Linear-a series of reactions to generate a final product.
•Cyclic-a series of reactions that regenerate the first reactant.

5. METABOLISM AND CELL STRUCTURE
•Prokaryotic cells-have no nucleus and are found only in bacteria.
•The DNA that governs the reproduction of prokaryotic cells is usually circular molecule found
near the center of the cell in a region called the nucleoid.
•Eukaryotic cell-is a cell in which the DNA is found in a membrane-enclosed nucleus. Cell that
are found in all higher organisms.

6. THE CELL
Cytoplasm
-the water-based material of a eukaryotic cell that lies between the nucleus and the outer
membrane of the cell.
Organelles-a minute structure within the cytoplasm of a cell that carries out a specific
cellular function.
Cytosol-is the water-based fluid part of the cytoplasm of a cell.
The three important types of organelles: are ribosomes, lysosomes, and mitochondria.

7. •Ribosomes-are the sites of protein synthesis.
•Lysosome-an organelle that contains hydrolytic enzymes needed for cellular rebuilding,
repair, and degradation.
•Bacteria and viruses “trapped” by the body’s immune system are degraded and
destroyed by lysosome enzymes.
•Mitochondrion-an organelle that is responsible for the generation of most of the energy for a
cell.
Outer membrane-50% lipid and 50% protein; freely permeable to small molecules.
Inner membrane-20% lipid and 80% protein; highly impermeable to most substances.

8. OVERVIEW OF BIOCHEMICAL ENERGY PRODUCTION
Stage Description
Stage 1-Digestion Begins in the mouth, continues in the stomach, and is completed in the small
intestine.
The end product-glucose and other monosaccharides from carbohydrates; amino
acids from proteins; fatty acids and glycerol from fats and oils.
Stage 2-Acetyl group formationInvolves numerous reactions some of which occur in the cytosol of cells and some
in cellular mitochondria.
Small molecules from digestion are further oxidized.
Primary products include two-carbon acetyl units and the reduced coenzyme
NADH.
Stage 3-Citric acid cycle Occurs inside mitochondria.
Acetyl groups are oxidized to produce CO2 and energy.
Some of the energy released by these reactions is lost as heat, and some is carried
by the reduced coenzymes NADH and FADH2 to the 4
th
stage.
CO2 that is exhaled as part of the breathing process comes primarily from this
stage.
Stage 4-Electron transport chain
and Oxidative phosphorylation
Occurs inside mitochondria.
NADH and FADH2 supply the “fuel” needed for the production of ATP molecules,
the primary energy carriers in metabolic pathways.
O2, inhaled via breathing, is converted to H2O in this stage.

10. CITRIC ACID CYCLE
•Is the series of biochemical reactions in which the acetyl portion of acetyl CoA is oxidized to
carbon dioxide and the reduced coenzymes FADH2 and NADH are produced.
•Also known as the “Krebs cycle” and tricarboxylic acid cycle.
•The chemical reactions of the citric acid cycle take place in the mitochondrial matrix.
•Oxidationproduces NADH or FADH2 (4 of the 8 steps.)
•Decarboxylationof a carbon chain is shortened by the removal of a carbon atom as a CO2
molecule (2 of the 8 steps.)
•It is the main source of energy for cells and an important part of aerobic respiration.

12. CITRIC ACID CYCLE
•Overall summary equation:
•This is obtained by adding together the individual reactions of the cycle.

13. Important Features of the cycle:
1.The “fuel” for the cycle is acetyl CoA, obtained from the breakdown of carbohydrates, fats, and proteins.
2.Four of the cycle reactions involve oxidation and reduction. The oxidizing agent is either NAD+ (three
times) or FAD (once). The operation of the cycle depends on the availability of these oxidizing agents.
3.In redox reactions, NAD+ is the oxidizing agent when a carbon-carbon double bond is formed.
4.The three NADH and one FADH2 that are formed during the cycle carry electrons and H+ to the electron
transport chain through which ATP is synthesized.
5.Two carbon atoms enter the cycle as the acetyl unit of acetyl CoA, and two carbon atoms leave the cycle
as two molecules of CO2. The carbon atoms that enter and leave are not the same ones. The carbon
atoms that leave during one turn of the cycle are carbon atoms that entered during the previous turn of
the cycle.
6.Four B vitamins are necessary for the proper functioning of the cycle: riboflavin (in both FAD and the a-
ketoglutarate dehydrogenase complex), nicotinamide (in NAD+), pantothenic acid (in CoA—SH), and
thiamin (in the a-ketoglutarate dehydrogenase complex).
7.One high-energy GTP molecule is produced by phosphorylation.

14. ELECTRON TRANSPORT CHAIN
•It is a series of biochemical reactions in which electrons and hydrogen ions from NADH and
FADH2 are passed to intermediate carriers and then ultimately react with molecular oxygen
to produce water.
•NADH and FADH2 are oxidized in this process.
•Electrons that pass through the various steps of the electron transport chain (ETC) lose some
energy with each transfer along the chain.

15. ELECTRON TRANSPORT CHAIN
•The enzymes and electron carriers needed for the ETC are located along the
inner mitochondrial membrane.
•Four protein complexes, which are tightly bound to membrane.
Complex I: NADH-coenzyme Q reductase
Complex II: Succinate-coenzyme Q reductase
Complex III: Coenzyme Q-cytochrome c reductase
Complex IV: Cytochrome oxidase

16. •Cytochromeis a heme-containing protein in which reversible oxidation and
reduction of an iron atom occur.

17. OXIDATIVE PHOSPHORYLATION
•Is the biochemical process by which ATP is synthesized from ADP as a result of
the transfer of electrons and hydrogen ions from NADH or FADH2 to O2
through the electron carriers involved in the electron transport chain.
•Coupled Reactions-are pairs of biochemical reactions that occur concurrently
in which energy released by one reaction is used in the other reaction.
e.g., Oxidative phosphorylation and oxidation reactions of the ETC.

18. •Complex I, III, and IV proton pumps
•Proton pumps
electrons: matrix sideinner mitochondrial membraneintermembrane space
ATP synthesisthe basis of this came from the high concentration of protons that build up in
the intermembrane space.
Chemiosmotic coupling-is an explanation for the coupling of ATP synthesis with electron
transport chain reactions that requires a proton gradient across the inner mitochondrial
membrane.