General Biology PDF

GENERAL BIOLOGY Reviewed by: Miss Christine Solias| 2nd Quarter 4. Active transport - Energy is required to move Topic Outline: Topic I : Intro to Cellular Respiration substances such as ion...

GENERAL BIOLOGY Reviewed by: Miss Christine Solias| 2nd Quarter 4. Active transport - Energy is required to move Topic Outline: Topic I : Intro to Cellular Respiration substances such as ions across the plasma membrane Topic II : Aerobic Respiration and it's Stages against their concentration gradients. 5. Secretion - In the cell, the packaging and transport of Prepared by: Klarisse Chua, Jaime Miguel Tusing secretory products require energy. INTRO TO CELLULAR RESPIRATION Energy Currency Cellular Respiration is the process by which cells in plants & animals break down sugar and turn it into energy, which is then used to perform work at the cellular level. The purpose of cellular respiration is to provide cells with the energy they 6. Bioluminescence - Some organisms, such as glow need to function. If living things could not get the energy they worms and bacteria, are able to convert chemical need out of food, it would be absolutely worthless. All living energy into light. things would eventually die, no matter the quality and amount of food. All living things require energy to function. While different Cellular Respiration is used to create usable energy from the organisms acquire this energy in different ways, they store foods that living things eat. It's important to know that the (and use it) in the same way. reactions involved in cellular respiration are catabolic, they break down molecules into smaller ones. This differs from anabolic reactions, which build bigger molecules from smaller ones. Cellular respiration involves a catabolic reaction in order to break down food into usable energy so that cells, and the living organisms that contain them, can survive and thrive. Significance of Energy to Living Organisms 1. Movement - Energy is required for the movement of cilia and flagella, muscle contraction and movement of chromosomes during cell division. A living cell cannot store significant amounts of free energy. 2. Maintaining a constant body temperature - Excess-free energy would result in an increase of heat in the Warm-blooded animals need heat energy to maintain cell, which would result in excessive thermal motion that a suitable body temperature in order to provide an could damage and then destroy the cell. Rather, a cell must be optimum internal environment for enzymes to able to handle that energy in a way that enables the cell to function. store energy safely and release it for use only as needed. 3. Anabolic processes - These are metabolic processes Living cells accomplish this by using the compound adenosine that consume energy to build complex molecules triphosphate (ATP). ATP is often called the “energy currency” from simple molecules. of the cell, and, like currency, this versatile compound can be used to fill any energy need of the cell. Liceo Science Club - Scikicks | 1  Major Stages in Aerobic Respiration Main Stages What happens during each stage? Glucose is converted to Glycolysis pyruvate in the cytosol of the cell. Pyruvate is degraded and Formation of acetyl CoA combined with coenzyme A to form acetyl coenzyme A in the mitochondrial matrix. When ATP is broken down, usually by the removal of its terminal phosphate group, energy is released. The energy is The acetate group of acetyl used to do work by the cell, usually by the released phosphate coenzyme A combines with Citric acid cycle or Krebs a four-carbon molecule binding to another molecule, activating it. Cycle (oxaloacetate) to form a six-carbon molecule ATP Structure and Function (citrate), Citrate is recycled to form oxaloacetate and Adenosine Triphosphate (ATP) is a nucleotide with unstable carbon dioxide is released as phosphate bonds that the cell hydrolyzes for energy. The ATP the waste product. molecule consists of the following: Electrons produced from glycolysis and the Krebs 1. Adenine - a nitrogenous base Oxidative Phosphorylation cycle are passed along a 2. Ribose - a five-carbon sugar (Electron transport and series of enzymes embedded 3. A chain of three phosphate groups Chemiosmosis) in the inner mitochondrial membrane, producing ATP via oxidative phosphorylation and chemiosmosis. ANAEROBIC RESPIRATION AEROBIC RESPIRATION During aerobic respiration, energy is released as fuel Aerobic respiration is not possible for organisms molecules are catabolized to carbon dioxide and water. One of living in anaerobic conditions. For these organisms, the most common pathways of aerobic respiration involves the glycolysis is the first, and fermentation occurs in the breakdown of the nutrient glucose. absence of oxygen. The last step of the cellular The overall reaction for the aerobic respiration of glucose is respiration process. summarized as follows: 𝐶6𝐻12𝑂6+6𝑂2 → 6𝐶𝑂2+6𝐻2𝑂 Fermentation is a type of anaerobic respiration. It is an extension of glycolysis that can generate ATP solely by substrate-level phosphorylation, as long as 2 there is a sufficient supply of NAD+ to accept The decarboxylation reaction removes a carbon electrons during the oxidation steps of glycolysis dioxide (CO2) molecule from pyruvate to yield acetaldehyde. Acetaldehyde is then reduced by In fermentation, glycolysis usually proceeds in NADH to form ethanol. This step regenerates aerobic conditions, producing a net yield of two NAD+ needed for glycolysis. ATP, two NADH, and two pyruvate molecules.. The overall equation for alcoholic fermentation is: However, the two pyruvate molecules are reduced, Glucose + 2ADP + 2Pi + 2H+ → 2 ethanol + and the NAD + necessary for the initiation of 2CO2 + 2ATP + 2H2O glycolysis is recycled. In this way, the cells will not deplete their store of NAD +, although they can LACTIC ACID FERMENTATION only produce two ATP. As a by-product of fermentation, either ethanol or lactic acid is produced. Fermentation is less efficient at using the energy from glucose since only two ATPs are produced per glucose molecule, compared to the 38 ATPs per glucose molecule produced by aerobic respiration. Most of the chemical energy (about 95%) of the glucose is still trapped in pyruvate. There are many During Lactic acid fermentation, pyruvate is types of fermentation, differing in the waste reduced directly by NADH to form lactate with no products formed from pyruvate. Two common types release of carbon dioxide. The overall reaction for are alcoholic fermentation and lactic acid the conversion of glucose to lactate is: Glucose + fermentation. 2ADP + 2Pi → 2 lactate + 2ATP + 2H2O Aerobic and anaerobic pathways of glucose Examples of organisms that are lactic acid metabolism fermenters are Lactobacillus and Streptococcus species. During intense such as running, lactate is Alcoholic fermentation - is an anaerobic process produced faster than the tissues can remove it. that converts pyruvate to carbon dioxide and Therefore, the lactate concentration begins to rise. ethanol. The presence of lactate in our muscles may cause MUSCLE ACIDOSIS which induces fatigue and muscle cramps. (although studies say otherwise) The lactate produced can be removed in a number of ways such as : (a) oxidation back to pyruvate when the oxygen supply is plentiful. (b) conversion to glucose through the process of gluconeogenesis via the Cori cycle in the liver. 3  which gives a sour taste Uses of Fermentation and causes the pH to Dairy products fall so that the milk proteins coagulate to Products Process produce yogurt. One Flour, sugar, water, and can add flavoring to a little salt are mixed produce yogurt with with yeast to form a various flavors. To dough. The yeast make cheese, the milk Bakery products- ferments the sugar, solids formed by the dough and cake producing ethanol and coagulation of milk are carbon dioxide. The pressed to remove carbon dioxide causes water. the dough to rise, Example of local food giving bread and cake a produced by soft texture. Baking fermentation include kills the yeast and Local Products burong mangga, evaporates the ethanol. binurong isda or hipon To make beer, yeast is (balao-balao), used to ferment cereals sinamak/pinakurat and such as barley. Hops many more. are included to give Beer and wine flavor. The products of fermentation are distilled to produce beer. In wine-making, What is anaerobic respiration? Prepared by : Jaime Miguel Tusing grapes are fermented instead of cereals. Most organisms require oxygen to respire and live, however Ethanol is used in some organisms can continue to respire when oxygen runs industry as a solvent out. This is anaerobic respiration. Humans can do this for a short time, resulting in lactic acid building up in our muscles. and manufactures other Some fungi and plants respire anaerobically to release less organic compounds energy but stay alive. Ethanol such as ethanoic acid and esters. Ethanol can be manufactured Anaerobic respiration equations industrially by using yeast to ferment cane Lactic Acid : Glucose + 2ADP + 2Pi → 2 lactate + 2ATP + sugar. Cane sugar is 2H2O sucrose. During fermentation, an Alcoholic : Glucose + 2ADP + 2Pi + 2H+ → 2 ethanol + enzyme converts 2CO2 + 2ATP + 2H2O sucrose into glucose and fructose. Lactobacillus (bacteria) Aerobic Respiration Anaerobic Respiration converts lactose (milk Releases a relatively large Releases a small amount of sugar) into lactic acid, amount of energy. energy very quickly. 4 Oxygen is present. Oxygen is absent or not very abundant. It is an electron carrier used to temporarily store energy. Glucose is completely Glucose is not completely oxidized. oxidized and the products It is Reduced to NADH when it picks up two still contain energy. electrons and one hydrogen ion. Different factors to be considered when knowing FAD+ (Flavin adenine dinucleotide) is another coenzyme. the differences between the two types of cellular respiration Reduced to FADH2 when succinate is oxidized. Two types of phosphorylation Factors Aerobic Anaerobic Respiration Respiration 1. Substrate-level phosphorylation is a metabolic process that produces ATP or GTP by directly Main function Production of Production of transferring a phosphate group from a substrate to ATP from food ATP without the ADP or GDP. such as use of oxygen carbohydrate, lipid and protein 2. Oxidative phosphorylation is the mechanism through which ATP generation is linked to the flow of Site of Reaction Cytoplasm and Cytoplasm electrons along the mitochondrial electron transport mitochondrion chain and the accompanying consumption of oxygen is known as oxidative phosphorylation. Production of 36 to 38 ATP per 2 ATP per ATP glucose molecule glucose moleculr Where does it takes place? Sustainability Long-term Short-term It takes place in two organelles of the cell: Production of Does not produce Produces lactic acid Glycolysis in the Cytoplasm. Oxygen Yes No requirement Krebs Cycle and ETC in the Mitochondria. Recycling of Through the In lactic acid MITOCHONDRIA NADH electron transport fermentation (i.e, system muscle cells; in alcohol They have a smooth outer membrane and an inner fermentation membrane folded into cristae (pyrovate is converted to Cristae present a large surface area for enzymes that carbon dioxide synthesize ATP and ethanol) Participating Most cells Yeast, other fungi, The inner membrane creates two compartments: cells prokaryotes, intermembrane space and mitochondrial matrix muscle cells Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix What carries the electrons? GLYCOLYSIS NAD+ (Nicotinamide adenine dinucleotide) is a coenzyme. 5 Glycolysis is from the terms glycose (old name for glucose) and lysis (degradation). It is a series of reactions that converts (ii) The addition of the phosphoryl group changes the glucose to pyruvate with the accompanying production of ATP biologically inert (chemically inactive) glucose into a labile and NADH. (easily broken down) form which is capable of being further metabolized. Two Phases of Glycolysis (b) Step 2: Isomerization- The second reaction of glycolysis is Phase 1: Energy Investment Phase (Reactions 1 to 5) an isomerization process in which glucose 6- phosphate is rearranged to become its isomer fructose 6-phosphate. Glucose (6C) is cleaved to give 2 molecules of (Isomers are molecules with the same molecular/empirical glyceraldehyde-3-phosphate (3C each) formula, the same number of atoms but have different arrangements of atoms in space.) Uses 2 ATP molecules (c) Step 3: Phosphorylation - A second ATP is utilized to Phase 2: Energy Pay-off Phase (Reactions 6 to 10) phosphorylate fructose 6-phosphate to form fructose 1,6-bisphosphate. This step is catalyzed by 2 glyceraldehyde 3-phosphate molecules are phosphofructokinase. converted to 2 pyruvate molecules. (d) Step 4: Cleavage- Fructose 1,6-bisphosphate is hydrolyzed Generates 4 ATP and 2 NADH to form two three-carbon products: dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (G3P). However, only G3P can proceed immediately through glycolysis. (e) Step 5: Isomerization- Succeeding reactions of glycolysis utilize G3P as the substrate. Thus, DHAP is isomerized to form G3P. The two molecules of G3P then undergo identical reactions in the energy payoff phase. (f ) Step 6: Oxidation/dehydrogenation and phosphorylation - Each G3P molecule is oxidized and NAD + is reduced to form NADH + H +. The product, phosphoglycerate, reacts with inorganic phosphate to yield a high-energy substrate, 1,3-bisphosphoglycerate. (g) Step 7: Substrate-level phosphorylation. One phosphate group from each 1,3-bisphosphoglycerate molecule is transferred to ADP to form ATP and 3-phosphoglycerate. The transfer of a phosphate group from a phosphorylated intermediate is known as substrate-level phosphorylation. (h) Step 8: Isomerization- 3-phosphoglycerate is rearranged to Additional notes on glycolysis form 2-phosphoglycerate by shifting the position of the phosphate group. (a)Step 1: Phosphorylation- The ATP-dependent phosphorylation of glucose to form glucose 6-phosphate is the (i) Step 9: Dehydration- A molecule of water is removed from first reaction of glycolysis, and is catalyzed by the enzyme 2-phosphoglycerate to form another high-energy compound, hexokinase. The phosphorylation accomplishes two goals: phosphoenolpyruvate ( PEP ). PEP has a phosphate group attached to an unstable bond. (i) The non-ionic glucose is converted into an anion causing glucose to be trapped in the cell since glucose 6-phosphate cannot diffuse out of the cell due to the negative charge. 6 (j) Step 10: Substrate-level phosphorylation- The phosphate group from PEP is transferred to ADP to form ATP. PEP is then converted to pyruvate. Formation of Acetyl Coa Through a process called oxidative decarboxylation, the link reaction converts the three-carbon pyruvate from glycolysis into a two-carbon molecule, acetyl coenzyme A, and a molecule of carbon dioxide. KREBS CYCLE It has three names: the citric acid cycle, the Krebs Oxidative Phosphorylation: Electron transport cycle, or the tricarboxylic acid cycle. Citrate, the chain and chemiosmosis citric acid anion, is one of the intermediates. Hans Krebs did much of the groundbreaking work on this Very little energy is produced during glycolysis and the Krebs metabolism. Finally, tricarboxylic acids are some of cycle. Most of the energy locked in the original glucose the intermediates, each has three classes of carboxyl molecule will be released by the electron transport chain and (-COOH). chemiosmosis. The Krebs cycle is a series of enzymatic reactions The electron transport chain is a network of electron-carrying that is essential to the metabolism of aerobic proteins located in the folds of the inner membrane ( cristae ) organisms. The enzymes of the Krebs cycle are of the mitochondria. located in the mitochondrial matrix and are in close association with the electron transport chain. Oxidative phosphorylation can be described as the process in which ATP is formed as a result of the transfer of electrons The Krebs cycle consists of eight sequential from NADH or FADH2 to oxygen by a series of electron reactions. Most of the reactions are carriers. oxidation-reduction reactions and decarboxylation reactions, each catalyzed by a specific enzyme in the mitochondrial matrix. What is Electron transport chain? Electron transport is a series of redox reactions that resemble a relay race or bucket brigade in that electrons are passed rapidly from one component to the next, to the endpoint of the chain where the electrons reduce molecular oxygen, producing water. Overall, what does the electron transport chain do for the cell? Regenerates electron carriers. NADH and FADH2 pass their electrons to the electron transport chain, turning back into NAD+ and FAD. This is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running. 7  Makes a proton gradient. The transport chain builds a (b) FADH2 activates only two pumps because the FADH2 proton gradient across the inner mitochondrial enters the electron transport chain at the second entry point. membrane, with a higher concentration of H+ in the Therefore, only two ATP are produced. intermembrane space and a lower concentration in the matrix. This gradient represents a stored form of energy, and, as we’ll see, it can be used to make ATP. Chemiosmosis Hydrogen ions in the matrix space can only pass through the inner mitochondrial membrane through an integral membrane protein called ATP synthase. This complex protein acts as a tiny generator, turned by the force of the hydrogen ions diffusing through it, down their electrochemical gradient. The turning off parts of this molecular machine facilitates the addition of a phosphate to ADP, forming ATP, using the potential energy of the hydrogen ion gradient. Summary of ATP production Summary of Cellular Respiration Stages Summary Some Some End Starting Products Materials Glycolysis Series of Glucose, Pyrovate, (in cytosol) reaction in ATP, ATP, NADH which NAD+, Pi Theoretical Yield of ATP glucose is degraded to pyrovate; net One ATP molecule is produced each time a proton pump is profit of 2 activated. ATPs; (a) Each molecule of NADH activates three pumps. Thus, hydrogen three ATP are produced. atoms are transferred 8  to carries; proceed anaerobicall y Formation of Pyrovate is Pyrovate, Acetyl CoA, acetyl CoA degraded coenzyme CO2, (in and A, NAD+ NADH mitochondri combined a) with coenzyme A to form acytel CoA; hydrogen atoms are transferred to carries; CO2 is released Citric acid Series of Acetyl CoA, CO2, cycle (in reactions H2O, NADH, mitochondri which the NAD+, FADH2, a) acetyl CoA FAD, ADP, ATP is degraded Pi to CO2; hydrogen atoms are transferred to carries; ATP in synthesized Electron Chain of NADH, ATP, transport and several FADH2, O2, H2O,NAD, chemiosmos electron ADP, Pi FAD is (in transfort mitochondri molecules; a) electrons are passed along chain; released energy is used to form a proton gradient; ATP is synthesized as protons diffuse down the gradient; oxygen is final electron acceptor 9