Cellular respiration introduction 10grade.pptx

Based on pearson,

1. CELLULAR RESPIRAT ION TSTW

2. HOW DO CELLS OBTAIN ENERGY? Cells require a continuous supply of energy to power the multitude of metabolic reactions that are essential just to stay alive. we describe the cellular reactions that transfer energy from energy-storage molecules, particularly glucose, to energy-carrier molecules, such as ATP.

3. The second law of thermodynamics tells us that every time a spontaneous reaction occurs, the amount of useful energy in a system decreases and heat is produced Cells are relatively efficient at capturing chemical energy during glucose breakdown when oxygen is available, storing about 40% of the chemical energy from glucose in ATP molecules, and releasing the rest as heat.

4. E nergY It is the ability to perform a job. j ob is the transfer of energy to an object so that it moves. C hemical energy, IS THE energy contained in molecules and released by chemical reactions, drives this muscle work.

5. Cells use specialized molecules, such as ATP, to take, briefly store, and transfer energy from one chemical reaction to the next. Muscle contractions result in interactions between specialized proteins, driven by the chemical energy released from ATP molecules

6. the Sun's nuclear reactions generate kinetic energy in the form of light, which produces huge increases in entropy within the Sun in the form of heat. In fact, the temperature at the center of the Sun is estimated to be about 16 million C. Living things use a continuous flow of solar energy to synthesize complex molecules and maintain orderly structures, to "fight disorder." Organized, low-entropy systems of life do not violate the second law of thermodynamics because they are the product of a constant flow of luminous solar energy.

7. HOW DOES ENERGY FLOW IN CHEMICAL REACTIONS? A chemical reaction is a process that forms or breaks the chemical bonds that hold atoms together. Chemical reactions convert some chemical substances, the reactants, into others, the products. All chemical reactions give off energy or require a net input of energy.

8. HOW DOES ENERGY FLOW IN CHEMICAL REACTIONS? A reaction is exergonic (from the Greek term meaning "energy outside") if it releases energy; that is, whether the initial reactants contain more energy than the final products. All exergonic reactions release some of their energy as heat ener gy

9. HOW DOES ENERGY FLOW IN CHEMICAL REACTIONS? A reaction is exergonic (from the Greek term meaning "energy outside") if it releases energy; that is, whether the initial reactants contain more energy than the final products. All exergonic reactions release some of their energy as heat ener gy HIGH LOW MOLECULES ENERGY ACTIVATION ENERGY REQUIRED What other possible sources
of activation energy is there?

10. HOW DOES ENERGY FLOW IN CHEMICAL REACTIONS? -Activation energy

11. HOW DOES ENERGY FLOW IN CHEMICAL REACTIONS? A reaction is endergonic ("energy within") if it requires a net input of energy; that is, if the products contain more energy than the reactants. Endergonic reactions require an energy input from an external source.

12. HOW IS ENERGY TRANSPORTED IN THE CELLS? Energy-carrying molecules are energetic and unstable molecules that are synthesized at the site of the exergonic reaction and capture some of the energy released. These carrier molecules work in a similar way to rechargeable batteries: they take a charge of energy in an exergonic reaction, move to another part of the cell, and release the energy to drive the endergonic reaction. Because energy-carrying molecules are unstable, they are used only to capture and transfer energy within cells. They cannot carry energy from one cell to another nor are they used for long-term storage. Almost all organisms are driven by the breakdown of glucose. By combining glucose with oxygen and releasing carbon dioxide and water, cells acquire the chemical energy of the glucose molecule. This energy is used to perform cellular work, such as forming complex biological molecules and contracting muscles. But glucose cannot be used directly to drive these endergonic processes, instead the energy released by glucose degradation is first transferred to an energy-carrying molecule.

13. ATP - The body's most common energy-carrying molecule.
- It is a nucleotide composed of the nitrogenous base adenine, sugar ribose and three phosphate groups - The formation of ATP is endergonic, it requires a contribution of energy that is captured in this new energy molecule. ATP stores energy in chemical bonds and transports it to places in the cell where energy-demanding reactions take place. It is released as ATP is degraded and ADP and P are regenerated E.T: These energetic electrons, along with hydrogen ions (H, present in the cytosol) are taken up by special energy-carrying molecules called electron transporters. Common electron transporters are nicotinamide adenine dinucleotide (NADH) and its related molecule, flavin adenine dinucleotide (FADH2). Charged electron transporters donate their energetic electrons to other molecules that are in the pathways that generate ATP.

14. ATP - La molécula portadora de energía más común del cuerpo . - es un nucleótido compuesto de la base nitrogenada adenina, el azúcar ribosa y tres grupos fosfatos

15. Cells are known to couple reactions, so that they drive the endergonic reactions that require energy with the exergonic reactions that release it. We also learned that cells synthesize energy-carrying molecules that capture energy from the exergonic reactions and transports it to the endergonic reactions. But how do cells control all the biochemical reactions that are needed to maintain the chemical balance that is necessary for life?

16. BIOLOGIC CATALYSTS Catalysts are molecules that accelerate the rate of reaction without being consumed or permanently altered. A catalyst accelerates a reaction by reducing the activation energy of the reaction.
Catalysts speed up reactions because they decrease the activation energy that is required for the reaction to start.
Catalysts can accelerate exergonic and endergonic reactions, but they cannot cause an endergonic reaction to occur spontaneously. Endergonic reactions
They need a supply of energy, with or without a catalyst.
Catalysts are not consumed or permanently changed in the reactions they promote.

17. BIOLOGIC ENZIMES Some enzymes need certain small non-protein helper organic molecules, coenzymes, to function. Many water-soluble vitamins (such as B vitamins) are essential for humans because the body uses them to synthesize coenzymes. The enzymes, which can catalyze several million reactions per second, use their three-dimensional structures to orient, distort and reconfigure other molecules and exit unchanged. Cells employ highly specialized biological catalysts called enzymes, proteins that are made up of amino acids. An enzyme catalyzes few chemical reactions. Almost all enzymes catalyze a single reaction that encompasses specific molecules, even leaving very similar molecules intact.
Exergonic and endergonic reactions are catalyzed by enzymes. For example, the synthesis of ATP from ADP and P is catalyzed by the enzyme ATP synthase. This enzyme captures some of the energy released in the series of reactions that degrade glucose and then stores it in ATP.

18. BIOLOGIC ENZIMES The function of an enzyme is determined by its structure. Each enzyme has a "pouch" place called an active site, into which one or more reactant molecules called substrates can enter Remember that proteins have complex three-dimensional shapes (see Figure 3-20). Its main structure is determined by the precise order in which the amino acids are linked. The amino acid chain then folds in on itself in a configuration called a secondary structure (usually like an alpha helix or a folded beta sheet). The protein immediately acquires the twists and turns of the tertiary structure. Some enzymes also contain peptide units bound together in a quaternary structure. The order of amino acids and the way a protein's amino acid chains rotate, and fold creates the distinctive shape of the active site and a specific distribution of electrical charges within it. An enzyme and its substrate fit exactly; only certain molecules can enter the active site. Take, for example, the enzyme amylase. It degrades the starch molecules by hydrolysis, but leaves the cellulose molecules intact, although both consist of chains of glucose molecules. A different way of bonding between the glucose molecules in cellulose prevents them from entering the enzyme's active site (if you chew on a cracker for a long time, you'll notice the sweet taste of the glucose molecules in the starch in the cookie, which breaks down the amylase in the saliva). The stomach enzyme pepsin is selective for proteins and attacks them at many sites in the amino acid chains. Other enzymes that digest proteins (such as trypsin) break only the bonds between specific amino acids. The digestive system makes different enzymes that work together to completely break down dietary proteins into their component amino acids.

19. BIOLOGIC ENZIMES

20. METABOLIC PATHWAYS Metabolic pathways can be described as a series of chemical reactions that start with a substrate and finish with a product. Metabolic pathways are integrated and controlled enzyme catalysed reactions within a cell. In animals, specific metabolic pathways can produce vitamins and hemoglobin. INIITIAL REACTANT ENZYME 1 ENZYME 2 ENZYME 5 ENZYME 3 ENZYME 4 ENZYME 6 FINAL PRODUCT

21. There are different types of metabolic pathways – some are anabolic and some are catabolic. Anabolic – this type of pathway requires energy and is used to build up large molecules from smaller ones (biosynthesis). Catabolic – this type of pathway releases energy and is used to break down large molecules into smaller ones (degradation). METABOLIC PATHWAYS An example of an anabolic reaction is photosynthesis, where plants make glucose molecules from different raw materials. An example of a catabolic reaction is the process of food digestion, where different enzymes break down food particles so they can be absorbed by the small intestine. Metabolic pathways can be reversible or irreversible. Almost all pathways are reversible.

22. Few organisms store glucose in its simple form. Plants convert glucose to sucrose or starch for storage. Humans and many other animals store energy in molecules such as glycogen (a long chain of glucose molecules) and fat (see Chapter 3). Although most cells can use a variety of organic molecules to produce ATP, in this chapter, we focus on the breakdown of glucose, which all cells can use as an energy source. Glu- cose breakdown occurs via two major processes: It starts with glycolysis and proceeds to cellular respiration if oxygen is avail-able. Some energy is captured in ATP during glycolysis, and far more is captured during cellular respiration

23. METABOLIC PATHWAYS Metabolic pathways can be described as a series of chemical reactions that start with a substrate and finish with a product. Metabolic pathways are integrated and controlled enzyme catalysed reactions within a cell. In animals, specific metabolic pathways can produce vitamins and hemoglobin. INIITIAL REACTANT ENZYME 1 ENZYME 2 ENZYME 5 ENZYME 3 ENZYME 4 ENZYME 6 FINAL PRODUCT

24. GLYCOLISIS Glycolysis ultimately splits glucose into two pyruvate molecules. One can think of glycolysis as having two phases that occur in the cytosol of cells. The first phase is the "investment" phase due to its usage of two ATP molecules, and the second is the "payoff" phase. These reactions are all catalyzed by their own enzyme, with phosphofructokinase being the most essential for regulation as it controls the speed of glycolysis. Glycolysis occurs in both aerobic and anaerobic states. In aerobic conditions, pyruvate enters the citric acid cycle and undergoes oxidative phosphorylation leading to the net production of 32 ATP molecules. In anaerobic conditions, pyruvate converts to lactate through anaerobic glycolysis. Anaerobic respiration results in the production of 2 ATP molecules. Glucose is a hexose sugar, meaning it is a monosaccharide with six carbon atoms and six oxygen atoms. The first carbon has an attached aldehyde group, and the other five carbons have one hydroxyl group each. During glycolysis, glucose ultimately breaks down into pyruvate and energy; a total of 2 ATP is derived in the process (Glucose + 2 NAD+ + 2 ADP + 2 Pi --> 2 Pyruvate + 2 NADH + 2 H+ + 2 ATP + 2 H2O). The hydroxyl groups allow for phosphorylation. The specific form of glucose used in glycolysis is glucose 6-phosphate.