Dr Praveen Kumar Agrawal is teaching live on Unacademy Plus
Lesson3 Respiration : Some basic Concepts NCERT Class XI Dr. P. K. Agrawal M.Sc, Ph.D., CSIR NET (JRF), SRF, GATE, FIAZ Youtube Channel with over 1 million views 20 Years of Pre-medical teaching experience Ex- Faculty, Allen Career Institute, Kota Chapter- 14 Visit following link to follow my profile https://unacademy.com/user/biologybypkagrawal-6909
Aerobic and anaerobic respiration . The respiration which takes place in the presence of oxygen called aerobic respiration. But sometimes the food is oxidized even in the absence of oxygen. It is called anaerobic respiration. . Aerobic respiration is the perfect/complete respiration as the entire food (substrate) is oxidized to CO2 with the release of heavy energy. . However in anaerobic respiration food is not completely oxidized to CO2. It is converted in to lactic acid or ethyl alcohol, with the release of a little amount of CO2 and energy. . When glucose is the respiratory substrate, the glycolysis is the first step which common to both types of respiration. . In glycolysis the glucose is changed to pyruvic acid. . In aerobic conditions the pyruvic acid enters the mitochondria and follows the Krebs' cycle. But in anaerobic conditions the pyruvic acid still remain in the cytoplasm and is changed either to ethyl alcohol or to lactic acid (anaerobically). This anaerobic respiration is also called fermentation.
Differences in aerobic and anaerobic respiration Aerobic respiration Anaerobic respiration It occurs in the presence of oxygen. There is an exchange of oxygen and CO2 between There is no such exchange. organism and its environment. The substrate is completely oxidised It occurs in mitochondria It involves Krebs' cycle and ETS. Water is produced in the end Energy production is high (686 kcal/mol of glucose). Very low (about 50 kcal/mol of glucose). CO2 production is high. It occurs in the absence of oxygen. The substrate is not completely oxidised. It occurs in cytoplasm. There is no Krebs' cycle or ETS. Instead there is fermentation. No water is produced. CO2 production is less.
Steps in respiration In aerobic conditionsKrebs' cycle and ETS RespirationGlycolysis (Common) In anaerobic conditionsFermentation Krebs'cycle co and Water Complete oxidation) Aerobic conditions Reduced coenzymes In ETS Glycolysis Glucose Pyruvic acid ATP Reduced coenzymes (Do not give ATP) Anaerobic conditions Alcohol or lactic acid + Co2 (Incomplete oxidation) Fermentation
Respiratory fuel (Substrate) The substrate, fuel or the foodstuff which can provide energy during respiration is called respiratory substrate or fuel. It can be a carbohydrate, fatty acid or a protein molecule. However of all these the carbohydrates are the most preferred substrate for the respiration. Carbohydrates, mainly glucose easily undergoes respiratory process and provides quick energy. The caloric value of carbohydrates, is 4.1 kcal. Physiological fuel value of carbohydrates is 4 kcal. Fats (lipids) are highly energetic (caloric value is 9.45 kcal, physiological fuel value is 9 kcal) compounds but they yield energy with a little difficulty. Fatty acids during respiration, first undergo a process called beta oxidation to form acetyl coenzymes. These acetyl coenzymes then enter the Krebs' cycle to release energy. Proteins are the least energetic (caloric value is 5.65 kcal, physiological fuel value is 4 kcal). These are usually not used by the body for energy requirement. These undergo respiration in extreme cases, when reserve food (carbohydrates and fats) is finished. Since proteins are the main structural components of the protoplasm, their respiration is called protoplasmic respiration. During respiration proteins first undergo deamination to form acetyl coenzyme, which then follows the Krebs' cycle.
Different kinds of foodstuff and their respiration Glycolysis Co2 Carbohydrates Beta oxidation Acetyl Fats Krebs' cycle CoA Deamination Proteins ATP (Energy) 2H ETS H,O
Request! Regularly watch lessons and revise them. Please like, comment and recommend this lesson Follow my profile https://unacademy.com/user/biologybypkagrawal-6909 ALL THE BEST