2 IntroductionRespiration is a process in which living cells break down glucose and release its stored energy in the form of ATPRespiration is necessary for life.Organisms obtain energy in a process called cellular respiration.The equation for cellular respiration is the opposite of the equation for photosynthesis.
3 Introduction 6. Cell respiration occurs in ALL cells. 7. It begins with glycolysis, and continues with either anaerobic respiration (AKA fermentation) if oxygen is absent or aerobic respiration if oxygen is present.
4 Organic Compounds C6H12O6 ATP Glycolysis ATP Oxygen Absent First Stages of Cellular RespirationOrganic Compounds C6H12O6ATPGlycolysisATPOxygen AbsentOxygen PresentFermentationAerobic Respiration
5 GlycolysisOccurs in the cytoplasmCan occur with or without oxygenGlucose is split into 2 molecules of pyruvic acid (which is a 3 carbon compound)In addition to pyruvic acid, 2 molecules of ATP and 2 molecules of NADH are formed for each molecule of glucose that is broken down.
6 Glycolysis5. End products of glycolysis a. 2 ATP (makes 4 but uses 2 ATP) b. 2 molecules of pyruvic acid c. 2 NADH d. 2 H2O 6. What happens to the pyruvic acid depends on: a. The organism involved b. presence or absence of oxygen
8 FermentationDefined as the process of breaking down pyruvic acid without the use of oxygenAlso called anaerobic respirationDoes not produce ATPDoes produce NAD+ which is reused during glycolysis2 forms of fermentation:a. Lactic acid fermentationb. alcoholic fermentation
9 Lactic Acid Fermentation 1. Pyruvic acid from glycolysis is converted into a molecule called lactic acid.2. Heavy exercise is often the reason for the lack of oxygen that prevents pyruvic acid from continuing on to aerobic respiration. This can cause a build up of lactic acid that results in cramping and muscle soreness.3. End products of lactic acid fermentation:a. Lactic acidb. NAD+ (used in glycolysis)c. 2 ATP (actually made during glycoysis)
11 Alcoholic Fermentation Occurs in the cytoplasm of some plant cells and some unicellular organisms such as yeast under anaerobic conditionsPyruvic acid from glycolysis is converted to ethyl alcoholEnd products:a. Ethyl alcoholb. Carbon dioxidec. NAD+ (used in glycolysis)d. 2 ATP (actually made during glycolysis)
13 Aerobic Respiration Occurs after glycolysis Occurs in the mitochondria Requires the presence of oxygen (aerobic)3 steps to aerobic respirationa. Formation of acetyl CoAb. Krebs cyclec. Electron Transport Chain
15 Formation of Acetyl CoA Pyruvic acid (from glycolysis) enters the mitochondria through a transport proteinIt joins with coenzyme A (CoA) to produce Acetyl CoAIn the process, NADH is producedAcetyl CoA can then enter the Krebs cycle
17 Krebs cycle AKA citric acid cycle Occurs in the matrix of mitochondria Discovered by Sir Hans Krebs in 1937Steps:a. acetyl enters the cycle to combine with oxaloacetic acid citric acidb. coenzyme A is released to be used againc. citric acid – carbon dioxide oxaloacetic acid (used again)
18 Krebs cycle5. During the cycle, carbon dioxide is released, NADH and FADH2 are formed, and ATP is produced 6. End results a. 6 NADH b. 4 CO2 c. 2 ATP d. 2 FADH2
20 Krebs cycle7. The carrier molecules (NADH and FADH2) transport electrons from the Krebs cycle to the ETC where water and more ATP are formed
21 ETC Occurs in the inner membrane of mitochondria Electrons are donated to the ETC by NADH and FADH2ATP is generated by chemiosmosisThe function of oxygen is to act as the final hydrogen acceptor to produce waterEach NADH produces 3 ATPEach FADH2 produces 2 ATP