Respiration.docx

**[Respiration]** Respiration is the process of changing chemical energy from food into a form of energy that can be used by cells to carry out their functions. There are two types of respiration;\ - Anaerobic Respiration: Respiration that does not require oxygen and produces small amounts of ener...

**[Respiration]** Respiration is the process of changing chemical energy from food into a form of energy that can be used by cells to carry out their functions. There are two types of respiration;\ - Anaerobic Respiration: Respiration that does not require oxygen and produces small amounts of energy\ - Aerobic Respiration: The release of energy from organic compounds. It needs oxygen and produces large amounts of energy [Metabolism] In every living cell of every organism there are millions of chemical reactions occurring all of the time, these reactions are called metabolism. There are two types of chemical reactions involved;\ - Anabolic Reactions: Build up complex compounds out of elements or out of simpler compounds. They obtain the energy that they need from adenosine triphosphate (ATP). ATP breaks down to adenosine diphosphate (ADP) and an inorganic phosphate. In the process, energy is released.\ ATP = ADP + P + energy\ Photosynthesis and protein synthesis are the most common reactions of this type\ - Catabolic Reactions: Break down more complex molecules into simpler ones and release energy in the process. The energy is used to convert ADP and P into ATP.\ ADP + P + energy = ATP\ The breaking of ATP into ADP and P, as well as respiration and digestion, are typical examples. *Functions of ATP\ *- Stores the energy released in reactions, such as photosynthesis or respiration, in a form that can be used by cells\ - Transports the energy around the cell from where it is produced to where it is required [The Energy Cycle\ ]- Respiration releases energy in the form of ATP. The ATP transfers the energy and once it reaches the location where the energy is required, it releases the energy forming ADP and an inorganic phosphate usually written as P.\ - The ADP and free phosphate are then available to be reassembled into ATP provided there is energy available. In the formation of ATP, a third phosphate is forced to join ADP.\ - Forcing the third phosphate requires energy and this energy is stored in the final high-energy bond of the ATP.\ - Metabolism produces waste materials such as urea, carbon dioxide and water. The removal of these waste products is called excretion. [Biochemistry of Respiration] *Stages of Respiration*[\ ]1. Glycolysis -- Glycolysis means the splitting glucose (6-carbon sugar), into two 3-Carbon molecules, which can be called either pyruvate or pyruvic acid.\ - Glycolysis occurs in the cytoplasm of the cell and does not require oxygen. It releases a small amount of energy in the form of ATP. For each molecule of glucose, 2 ATP must be used to start the reaction. 4 ATP are produced so there is a net gain of 2 ATP for each glucose molecule broken down.\ 2a. The Krebs cycle- The pyruvate now enters the matrix/lumen of the **mitochondrion** where it loses CO~2~ and 2 Hydrogen atoms. The remaining 2 Carbon, acetyl group, is attached to a carrier molecule, co-enzyme A, to form acetyl coenzyme A. The acetyl group is passed by co-enzyme A into a series of reactions called the Krebs cycle. A 4 Carbon compound bonds to the acetyl group forming a 6 Carbon compound. The co-enzyme A is detached and recycled. This 6 Carbon compound is converted in steps back to the 4 Carbon compound by losing two CO~2~s and 4 hydrogen pairs. One ATP is also released\ 2b. Electron Transport Chain -- This is the formation of ATP in the cristae using oxygen. The electrons from the 2 Hydrogen atoms are passed along a series of carrier molecules and the energy released in each transfer is used to make ATP. The hydrogen ions and electrons finally unite with oxygen to form water. The water may be used by the cell. [Aerobic Respiration] This is the breakdown of sugar to release energy in the absence of oxygen. It occurs in some bacteria and most animal cells e.g., muscle cells during strenuous exercise. The product is lactic acid. This reduces the efficiency of the cells. The acidity lowers the pH which slows down enzyme action and causes cramps and stiffness. The deeper and faster breathing at the end of strenuous exercise is needed to convert the lactic acid back into glucose in the liver.\ The equation for Aerobic respiration is the reverse of the equation for Photosynthesis C~6~H~12~O~6~ + 6O~2~ = 6CO~2~ + 6H~2~O\ Glucose + Oxygen = Carbon Dioxide + Water [Anaerobic Respiration(Fermentation)\ ]Fermentation is the anaerobic respiration of sugars. It is an example of biotechnology. Biotechnology is the manufacture of a useful product using living things. Bacteria and fungi are the main organisms used. Plants and animals can also be used. *Biological advantages of fermentation:* Source of energy in oxygen-deficient environments. *Disadvantages:* Only 2 ATPs are produced compared to 38 ATPs per glucose in aerobic respiration. Products are also toxic and must be excreted. *Uses:\ *Alcohol production, bread making, yoghurt and cheese making\ Antibiotics, insulin, human growth factor, clotting factors [Mandatory Practical -- Investigate the production of ethanol by yeast and testing for the presence of ethanol] \*\*Need to know in detail\*\* A picture containing sketch, design, brass, illustration Description automatically generated(8) *To produce alcohol using yeast:*\ - Prepare 400 ml of a 10% w/v glucose solution.\ - Into each of the two conical flasks, add 200 ml of the glucose solution.\ - To one of the conical flasks, add 5g of yeast and swirl. Label this 'yeast + glucose'.\ - The second flask acts as a control -- it has no yeast. Label this 'control'.\ - Half fill two fermentation locks with water. Attach one fermentation lock to each flask.\ - Place both flasks in an incubator at 30^O^C overnight.\ - As fermentation proceeds, bubbles of carbon dioxide are produced and bubble out through the fermentation lock.\ - Fermentation is complete when no more bubbles of CO~2~ are produced and when the solution becomes clear as the yeast settles to the bottom of the flask. *To show the presence of alcohol: Iodoform test for alcohol:\ *- Remove both flasks from the incubator and filter the contents of each into separate boiling tubes and label as before. Filter until 3 ml of each is collected.\ - To each boiling tube, add 3 ml of the potassium iodide solution and 5 ml of the sodium hypochlorite solution.\ - Warm gently for 4-5 minutes in the water bath.\ - Allow to cool and observe any changes.\ - Record and compare results.\ - Replicate the investigation or cross reference your results with other groups.\ - A yellow precipitate confirms that ethanol is present.