Metabolismo | Los secretos del cuerpo humano

METABOLISM

Metabolism: Ana (bolism) cata (bolism) ...

Welcome to a new blog post. Today I bring you the metro line of our body, anabolism and catabolism. I hope you find it interesting and help you with your study!

First of all, do you know what catabolism is? Catabolism is a process by which complex organic molecules are transformed into simpler ones. In it, energy is released that is stored in the phosphate bonds of ATP.

ATP acts as an energy molecule in metabolism. The synthesis of ATP is carried out in two different ways, by phosphorylation at the substrate level and enzymatic reaction with ATP-synthetases.

Enzymes are biocatalysts. When the activation energy is lowered, they increase the speed of the reaction and accelerate it. Also, all enzymes, except ribozymes, are globular proteins. There are also vitamins with coenzyme function.

The types of CATABOLISM that are distinguished are:

- CELLULAR RESPIRATION, which is divided into three phases:

The first is glycolysis by which pyruvic acid is obtained from glucose and takes place in the cytosol.
The second is the Krebs cycle where the pyruvic acid obtained in glycolysis is transformed into Acetyl-CoA and takes place in the mitochondrial matrix.
The third phase is the respiratory chain or electron transport chain made up of large protein complexes and small molecules that are ubiquinone and cytochrome c.

Chemosmosis , which is the energy lost by electrons, is used to pump the protons out. There they accumulate and when their concentration is high, the protons return to the mitochondrial matrix through internal channels with enzymes included in the membrane, called ATP synthetases.

By the way, in oxidative phosphorylation ATP-synthetases are made up of four parts. The parts move relative to each other when the protons flow through their inner channel. Fact that causes changes in three places that produce the union of an ADP and a phosphate group, thus generating an ATP.

- FERMENTATIONS are an anachronistic process, the final acceptor is an organic compound, and ATP synthesis occurs at the substrate level. Alcoholic fermentation is distinguished, which is the transformation of pyruvic acid into ethanol and carbon dioxide; lactic fermentation from which lactic acid is formed; butyric fermentation, which is the decomposition of carbohydrate substances of vegetable origin; and putrid fermentation in which organic and malodorous substances are obtained.

There are also other catabolic routes, which are lipid catabolism , which consists of breaking down the fatty acid with glycerin. The catabolism of proteins, which is the separation of amino groups and, with it, their elimination and the transformation of the rest of the resulting components into pyruvic acid, acetyl-coenzyme A or some compound of the Krebs cycle.

Source: own image.

On the other hand, we find ANABOLISM , which are redox and endothermic reactions by which a more complex molecule is formed using energy from a simple molecule. In autotrophic organisms, depending on the energy source, photosynthesis (light) or chemosynthesis (chemical reactions) will take place.

Focusing on PHOTOSYNTHESIS , it transforms light energy into chemical energy, it is carried out in chloroplasts, more specifically, in the photosynthetic pigments located inside the thylakoids. Photosynthesis is divided into two phases: the light phase and the dark phase. In turn, the LUMINOUS PHASE consists of two other phases:

Source: Wikimedia Commons.

- Acyclic : In this stage three processes occur: the photolysis of water, the photophosphorylation of ADP and the photoreduction of NADH. Photosystems II and I capture light photons which generate electron transport in the thylakoid membrane. In addition, to replace the transferred electrons, photosystem II causes a breakdown of a water molecule that gives rise to O2 and two protons. Cytochrome complexes, plastoquinone, plastocyanin, ferredoxin and ATP-synthetase also participate in the electron chain. It is the phase in which the majority necessary to pass to the dark phase is obtained, from 4 H + 1.33 ATP is obtained.

- Cyclic : It is responsible for producing energy necessary for the dark phase, only the photosystem I acts, therefore there will be no decomposition of water. The electrons enter the electron transport chain allowing the flow of protons that when passing through the ATP-synthetase will produce 2ATP.

In the DARK PHASE, the Calvin cycle takes place , which is a series of biochemical reactions that occur during the dark phase of photosynthesis where two phases can be distinguished:

- The fixation of CO2 to ribulose-1,5-diphosphate, thanks to the action of the enzyme rubisco and gives rise to a compound of 6 carbon atoms, which dissociates into 2 molecules of 3-phosphoglyceric acid (3 carbons ).

- The reduction of the fixed CO2 that after a series of reactions in which 2 ATP is spent and 2 NADH are reduced, the 3-phosphoglyceric acid is reduced and gives rise to glyceraldehyde-3-phosphate. The cycle could continue with the pentose-phosphate cycle, with the synthesis of glucose, fructose, starch, fatty acids or amino acids.

On the other hand, CHEMOSYNTHESIS consists of the synthesis of ATP from the energy that is given off in the oxidation reactions of certain inorganic substances.

Many of the reduced compounds used by bacteria are substances from the decomposition of organic matter. By oxidizing them, they transform them into mineral substances that can be absorbed by plants. These bacteria close the biogeochemical cycles, making life possible on the planet.

In heterotrophic organisms, the formation of precursor molecules occurs through anabolism. Where two phases can be distinguished: the biosynthesis of monomers from precursors and the biosynthesis of polymers from their monomers. Heterotrophic anabolism of carbohydrates, lipids, proteins and nucleic acids can be differentiated.

Diferencias entre catabolismo y anabolismo

Source: own image.

ACTIVITIES .

2. State the similarities and differences between photosynthesis and chemosynthesis.

Both photosynthesis and chemosynthesis are autotrophic anabolic processes. While in photosynthesis the energy to create the new bonds is obtained through sunlight, in chemosynthesis the energy comes from the oxidation of other molecules. On the other hand, photosynthesis is carried out by plants, algae, cyanobacteria and photosynthetic bacteria, chemosynthesis is carried out by chemoautotrophic bacteria.

4. What is understood by photolysis of water and how many molecules must undergo this process to generate one molecule of O2?

The photolysis of water is the breakdown of water due to sunlight that occurs in oxygenic photosynthesis. To generate an O2 molecule, two H2O molecules need to be broken since a water molecule when it breaks gives 2H +, 2e- and 1/2 O2.

5. Both in mitochondrial respiration and in the acyclic light phase there are enzymes that work with NADH or NADPH, an electron transport chain and ATP-synthetases, but there are certain differences. Answer the questions in the following table:

tabla características respiración celular y fotosíntesis.

7. In which organelles of the eukaryotic cell do the following metabolic processes take place?

β-oxidation of fatty acids: mitochondria.
Photophosphorylation: thylakoid membrane.
Glycolysis: cytosol.
Oxidative phosphorylation: mitochondrial ridges.
Capture of light by the antenna complex: photosystems (thylakoid membrane)
Calvin cycle: stroma.
Tricarboxylic acid cycle: mitochondrial matrix.

PAU ACTIVITIES

19. Describe the main processes that occur during the light-dependent phase (light phase) of photosynthesis. (Option A-June 2004)

The light phase takes place in the membranes of the thylakoids, when a photon is captured by the target pigment of the reaction center, it leaves the atom leaving it ionized. Electrons lost with the energy of the photon pass from one molecule to another, which are successively oxidized and reduced. Thus the electron transport chain is formed. The captured energy is invested in introducing H + through the membrane, which when passing through ATP-synthetase, gives rise to the formation of ATP.

Depending on the final electron acceptor, two processes are distinguished:

ACYCLIC LUMINOUS PHASE: Two photons arrive at photosystem II, which causes the excitation of the target pigment and chlorophyll P680 loses 2 electrons, which will pass through the chain. Chlorophyll replenishes its lost electrons through photolysis of H2O, which cleaves into 2 H + and 2 electrons. The lost electrons then pass through the electronic transport chain, from photosystem II, to festine, and later to plastoquinone. Subsequently, it passes to cytochrome b6-f and then to plastocyanin. Before these electrons reach photosystem I, it receives 2 photons of light, which cause chlorophyll P700 to become excited, and lose 2 electrons, which are captured by ferredoxin and from there transported to the reduced NADP +, where they are incorporated H + from the stroma, which are collected by a NADP + that is reduced to NADPH + H + (PHOTORREDUCTION NADP +). The energy given off by the movement of electrons is used to pump protons from the stroma into the thylakoid, creating an electrochemical gradient that makes the protons return to the stroma through ATP-synthetase, forming ATP (PHOTOPHOSPHORYLATION)

In summary, in this phase we have obtained ATP AND NADPH

CYCLIC LUMINOUS PHASE: Only photosystem I intervenes, it is a cyclic flow because the final electron acceptor is the reaction center of chlorophyll P700. As photosystem II does not participate, there is no photolysis of H2O and there is no reduction of NADP +. When two photons reach photosystem I, chlorophyll P700 loses 2 electrons that are transferred to ferredoxin, this to cytochrome b6-f (which pumps H + into the thylakoid), from here they go to plastoquinone, then to plastocyanin and from back to Photosystem I. The pumped protons will come out through ATP-synthetase causing ATP synthesis. Finally, at the end of this phase we have only obtained ATP.

20. Define and differentiate the following pairs of concepts referring to microorganisms: autotrophic / heterotrophic; chemosynthetic / photosynthetic; aerobic / anaerobic. (Option B-June 2002)

Autotrophic organisms are those that are capable of producing their own food through photosynthesis, or chemosynthesis. However, heterotrophic organisms are organisms that cannot produce their own food from inorganic sources and therefore feed on other organisms in the food chain.

Photosynthetic organisms are those capable of capturing solar energy and using it for the production of organic compounds. These include higher plants, some protists, and bacteria, which can convert carbon dioxide to organic compounds and reduce it to carbohydrates. On the other hand, chemosynthetic organisms are those that obtain chemical energy (ATP) from the oxidation of inorganic substrates such as acids, mineral salts, oxides, bases, anhydrides, etc.

Aerobic microorganisms are the organisms that require oxygen to live. The opposite of aerobic is anaerobic. In this case, anaerobic microorganisms do not use oxygen in their metabolic activities.

So far today's post. I hope it has served you and, see you next time! ;-)