1 General Biology - Lecture notes 1 PDF

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Lecture Notes Temmary 1 General Biology...

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TOPIC 3: CELLULAR METABOLISM.

METABOLISM

Metabolism will be the entirety of all the chemical reactions that happen in the cell, and those chemical reactions will be many, thousands of reactions, millions that need to be very synchronized and fast.

All living beings need an energy source and various basic chemical substances / bio-elements in order to live. There are two general strategies: I. Those of the heterotrophic organisms that must be able to absorb organic material from the environment, who break it and when the bonds of that organic material are broken, energy is released which the living Organism used for life, e.g. Animals. II. That of autotrophic organisms that are able to extract organic material rich in high energy bonds from an external energy source, e.g. the energy of the sun and the use of very simple materials such as Mineral salts. Once they have created this organic matter, they can break their bonds in order to gain energy for life.

ENZYMES

Chemical reactions take place in living beings, the product of which is the substrate of a later reaction, so they are very synchronized, chemical reactions in living beings have to take place very quickly and efficiently, and therefore the action of catalysts. These biological catalysts will be the enzymes, which in the vast majority of cases are proteins. (Catalysts: they accelerate chemical reactions, but are not influenced by them) in order to accelerate these reactions, they give the substrates an initial energy and then the reaction takes place automatically and spontaneously

 Accelerates a chemical reaction by lowering the activation energy (they are catalysts).  They are very effective and specific: each type of enzyme accelerates a certain chemical reaction.  The name of the enzyme is that of the substrate plus the suffix 'asa': sucrose, cellulose ...

 They form temporary bonds with the substrates and then regenerate: Temporarily binding means that it binds to the chemical substrate, whereby it turns into a product and then separates.  They have one or more active centers, which are specific parts of the enzyme through which it interacts with the substrate.  Some need cofactors: A cofactor is a molecule of many different natures that the enzyme needs to function. Many vitamins are cofactors.  The enzymatic action is characterized by the formation of a complex that represents the transition state. E + S IT IS E + P The substrate binds to the enzyme through numerous weak interactions such as: hydrogen bonds, electrostatic, hydrophobic, etc. at a certain point, the active center. This center is a small part of the enzyme made up of a series of aa that interact with the substrate.

ATP drives the cell work through coupling reactions. It is a nucleotide triphosphate.

ATP AND ELECTRON CARRIER

Many of the reactions that take place in cells require energy. The cell understands a “language”, ie the cell needs a form of energy that is compatible with its function in order to carry out these chemical reactions. FORMS OF ENERGY THAT UNDERSTAND CELLS. -

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ATP (adenosine triphosphate): is a form of energy that is compatible with the functioning of the cell. It is a nucleotide that functions as an energetic molecule (it consists of a sugar (ribose) to the carbon of the ribose is a nitrogen base (adenine) and in C5 it has 3 phosphate groups. When the union of the third phosphate with the second or the second with the first, energy is released, which is the energy necessary for the chemical reaction. Electron carriers or reducing power: They are molecules that store electrons that have a lot of energy, these can be used for the chemical reaction.

You cannot give sugar directly to the cell and pretend to use the sugar because the cell needs it to be compatible. Cellular respiration is the process by which the cell converts the energy contained in the nutrients into forms of energy that are compatible with the function of the cells.

THE RELEASE OF ENERGY

The series of reactions we are about to see consists of converting the energy contained in the chemical bonds of lipids, proteins and carbohydrates into a cell-compatible form of energy that will be ATP. There are two processes: 1. fermentation We assume glucose as an energy molecule. During fermentation, the 6C skeleton of glucose is broken down into two three-carbon molecules, this 6C molecule is called pyruvate. Since I've broken chemical bonds, energy is released which is converted into ATP (first step of fermentation called glycolysis (break lysis) glucose gluco) The second step: it will be the conversion of pyruvate to either lactic acid or lactate and then we are talking about lactic acid fermentation or the conversion of pyruvate to ethanol + CO2 and in this type of fermentation it is called alcoholic fermentation. In our body there are cells that can perform lactic acid fermentation, e.g. Muscle cells when subjected to very great exertion. Organisms that also perform lactic acid fermentation are bacteria that precipitate milk to make dairy products, e.g. Lactobacilli. Because the pH of the milk drops and the proteins sink to the bottom (precipitation) Alcoholic fermentation occurs in the making of bread, wine, and beer, and it is made by a yeast (which is the same in all three cases) called Sachoromyces cerevisae. All we have seen is a fermentation that does not require o2. When do our muscle cells undergo lactic acid fermentation? If we try hard, the amount of O2 will be limited and it will gain more energy from fermentation than O2 or without it. 2. . Cell respiration Depending on the organism, plants, fungi and animals breathe with o2 cell respiration. Cellular respiration in eukaryotes occurs in the mitochondria (which are cell organelles).

Structure: They are organelles surrounded by double membranes which are believed to be originally bacteria and which are an ancestor of eukaryotic phagocytosis (phagocytosis) and have developed a mutually beneficial relationship with it (L. Margulis) What evidence suggests this is true? That it has a double membrane, mitochondria have DNA, it's not just in the nucleus, its DNA is circular; In the mitochondria there are ribosomes that correspond to those of bacteria, they also have the typical size of a bacterium and divide like them, all these tests suggest that the mitochondria are bacterial, this theory is called the endosymbiotic theory. The chloroplast is also believed to be of bacterial origin, so the theory is the same

MITOCHONDRIA

Structure of the mitochondria: double membrane, one outer and one inner. Between the two membranes is a space called the intermembrane compartment, the inner one folds into a series of fringes inside, called mitochondrial ridges. The space inside the ribs is called the matrix (which is where the mitochondrial DNA is located) Cell respiration does not begin in the mitochondria, but just like fermentation and the first step is glycolysistakes place in the cytosol of the cell. During this glycolysis, glucose is converted into pyruvate, in this step ATP is formed and pyruvate gets into the mitochondria. What happens to pyruvate can be broken down into two parts: 1. Krebs cycle: takes place in the matrix of the mitochondria 2. Electron transport and synthesis of ATP: takes place in the ribs.

Function: ATP synthesis. Two independent processes: Matrix (interior of the mitochondria) Krebs cycle Mitochondrial ridges  Electron transport and ATP synthesis.

Note: Compared to fermentation, which begins with glucose, cellular respiration is able to break all glucose bonds, which results in much more ATP being obtained than fermentation. Cellular respiration is much more profitable. First in evolution was fermentation, then cellular respiration The endosymbiotic theory exists for the following features.    

Doyle membrane Contains DNA ' Own ribosome Big size

Proteins must first be broken down into amino acids and fats into glycerine. Step 1: Glycolysis Step 2: The pyruvate goes into the mitochondria, into the matrix and there it is converted into acetyl-CoA, this acetyl-CoA enters the Krebs cycle (chemical cycle) and thereby breaks all bonds of acetyl -CoA by compressing the molecule to the maximum, ie breaking all bonds. This energy, which arises when the bonds are broken, is converted on the one hand into ATP and on the other hand into reducing power = this electron carrier Breathing consists of 3 steps: glycolysis, Krebs cycle, electron transport The last step is to convert the energy of the reducing energy into ATP, the cell needs much more ATP than to reduce energy. In the end: water is produced,

CHLOROPLASTICS

You will have a double membrane that is the same: there will be an outer membrane and an inner membrane and of course an intermembrane compartment. The space inside the inner membrane is called the stroma, where the DNA, the ribosomes are…. Inside we also find stacked sacs with membranes called thylakoids with a circular shape and stacked, these thylakoids are stacked in structures called granum. Photosynthesis is carried out in the chloroplasts, which consists of the production of glucose, a molecule with high-energy bonds, starting from CO2, which supplies the carbon and this CO2 adds compounds, the energy to produce these links comes from sunlight....