INTRODUCTTION
Cellular respiration is the food molecules or organic molecules are broken down to harvest chemical energy which is them stored in the chemical bonds of adenosine triphosphate (ATP) and all organism need energy to survive and continue their live .There are also occurs in three stages which are glycolysis, Krebs cycle and electron transport. Glycolysis is breakdown of 1 glucose(6C)molecule in a series enzyme catalyzed reactions into 2 molecules of pyruvate (3C).Krebs Cycle is complete the breakdown of pyruvate to Electron transport chain is electrons are transferred by NADH and through 4 major protein series to combine with oxygen producing water.Cellular respiration is the controlled breakdown organic molecules when the carbon hydrogen bonds of glucose broken and electron are be transferred to oxygen and transfer of electrons during chemical reaction releases energy stored in organic molecules. This released energy is ultimately used to synthesize ATP. Cellular respiration can be divide in two which is aerobic respiration and anerobic respiration. Aerobic respiration is the process occurs in the presence oxygen and acts a final acceptor. An anaerobic respiration also known as fermentation process, occurs when oxygen is not present and on this part when divided more in alcoholic fermentation or lactic fermentation without no oxygen presence. The difference that two process is alcoholic fermentation produce three product which is ethanol, carbon dioxide and ATP while lactic acid fermentation produce only two product which is lactic acid and ATP energy).Fermentation is the process in the substances breaks down into a simpler substances. In this experiment the methylene blue is one of material as a redox indicator because that material(chemical),can lose or gain electrons from other substances The result what can get and see when methylene blue turned in blue is show that substance is oxidized and when turn colorless ,that show substances is reduce.This process when in the yeast cell will produces 2ATP,ethanol,product and carbon dioxide.
DISCUSSION
In this experiment , there were two test tubes which A and B. Test tube A was not placed into boiling water(in the video),so enzyme in this tube still reactive while test tube B was placed into boiling water, so the enzyme in this test tube already denatured. First step in this experiment,10 of fresh yeast was poured into the test tubes.Test tubes B was placed in a beaker of boiling water and after 5 minutes the result was show that the fresh yeast bec ome decolorized light blue because enzyme in the yeast cell start to denatured, but test tube A not insert to the boling water, so the test tube not show any colour. Then, 10 drops of blue methylene were dropped into each of the test tube and was well shaken. The result for test tube A and test tube B were same when drops of methylene blue.The colour on the test tube A was change from blue colour to light blue, when the fresh yeast and methylene blue were mixed together. This is because test tube B remain unchanged whether drops of methylene blue because the yeast cells denatured already, and the yeast dead in the high temperature. After that, test tubes were placed in water bath(38-42) for fifteen minutes ,the colour become decolorized because enzyme in the fresh yeast already reach 40 optimum temperature, that temperature effect heat activities the enzyme molecules to move faster and yeast will produce more carbon dioxide.Test tube B remain unchanged because the yeast was denatured.Last, a rubber stopper was inserted into each tube and test tube was shaken. The function of rubber stopper is to avoid gas or liquid form escaping test tube during this experiment. Test tube A show the colour was change from decolorized to light blue because when shaking, the abundance of oxgen is oxidized the methylene blue and when the rubber stopper was removed from test tube, yeast undergo aerobic respiration, so the colour show light blue.Test tube B remain unchanged when vigorous shaking because the cell in the fresh yeast already denatured,and not longer function or active, the high temperature also effect yeast to denatured.
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Yeast in the experiment aerobic respiration is excess oxygen,with give reaction in the test tube.Procedure number 2 very important because methylene blue in this experiment acts as dehydrogenase enzyme are removing from substrate and it will pass to NAD or FADH and be reduced coenzyme because methylene blue used as a redox indicator, which chemical solutions,that can donate and receive electrons from other substances.The colour in test tube will changed when solution contain methylene are blue colour when this substance is oxidized(loss of electrons) and turn colorless when reduce(acceptance of electrons),it is NAD substitute. NAD accepts electrons in glycolysis/link reaction/Krebs cycle and these get passed to oxidative phosphorylation/electron transfer chain when oxygen is the final electron acceptor.
Temperature when low (-),fresh yeast will not grow or die. Temperature-,yeast will grow and and grow fast with -,which is optimum temperature Fresh yeast when in the higher temperature or temperature boiling water will make the cells damaged and not longer function. Temperature of yeast solution increases so the velocity increases, kinetic energy of the particles increases ,number of collisions increases, this will make number of collisions increases ,number of enzyme-substrate complex formed will increases also. When temperature increases, the rate of respiration will increases, this two things are directly propotional.
In this experiment was happened error when the water not really boiled yet, this error can avoid with the temperature of the water readings should be taken using the thermometer, the thermometer will show ,when using the thermometer but this error don’t give big impact the result because the colour in test tube still same with theory. When taking a thermometer reading, the eye position should be exactly in front of the scale to avoid parallax error or take one paper to make the scale clearly when see. Second,thing can improve is change the apparatus syringe to pipet to get the correct measurement when poured fresh yeast in the test tubes.Third,wear the gloves and wear personal protective equipment(PPE)., in the case the chemical was used which methylene blue
CONCLUSION
In conclusion, this experiment was achieved the hypothesis and accept when the fresh yeast reacts with aerobic respiration(consume organic molecules and and anerobic respiration(does not require but consume compounds other than ) ,this show when the last procedure , which is a rubber stopper was inserted into each test tube was shaken. Aerobic respiration requires oxygen as the final electron acceptor. Fermentation not produced oxygen. Temperature also very important to yeast growth. Methylene blue very suitable to recognize the cell respiration in the yeast by using the methylene blue as artificial hydrogen redox indicator when accept the hydrogen atoms and the colour in test tube change because already reduced.
REFRENCES
- Sixth Form Biology. (2019, February 15). Yeast and methylene blue experiment [Video]. YouTube. https://www.youtube.com/watch?v=kobjT8hOqZ0&t=426s
- Fermentation and anaerobic respiration | Cellular respiration (article) | Khan Academy. (n.d.). Khan Academy. https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation/variations-on-cellular-respiration/a/fermentation-and-anaerobic-respiration
- Regulation of cellular respiration | Boundless biology. (n.d.). Lumen Learning – Simple Book Production. https://courses.lumenlearning.com/boundless-biology/chapter/regulation-of-cellular-respiration/
- McGraw-Hill Animations. (2017, June 4). Cellular Respiration Glycolysis, Krebs cycle, Electron Transport 3D Animation [Video]. YouTube. https://www.youtube.com/watch?v=7J4LXs-oDCU&t=81s
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