Cell Energy Essay

Associate Program Material Cell Energy Worksheet Answer the following questions: Cellular respiration: •What is cellular respiration and what are its three stages? Cellular respiration is the aerobic harvesting of energy from food molecules. The first stage of cellular respiration is Glycolysis. The second stage of cellular respiration is the citric acid cycle. Lastly, the third stage of cellular respiration is the electron transport. •What is the role of glycolysis? Include the reactants and the products. Where does it occur? The role of glycolysis is to split the sugars.

During this process a six-carbon glucose molecule is broken in half leaving two three-carbon molecules. The three-carbon molecules then donate high-energy electrons to NAD+, the electron carrier, forming NADH. Glycolysis also makes four ATP molecules directly when enzymes transfer phosphate groups from fuel molecules to ADP. It produces a net of two molecules of ATP per molecule of glucose. At the end of glycolysis there are two molecules of pyruvic acid that holds most of the energy of glucose which is harvested in the second stage of cellular respiration. What is the role of the citric acid cycle? Include the reactants and the products. Where does it occur? The role of the citric acid cycle is to finish extracting the energy of sugar by breaking the acetic acid molecules all the way down to CO2. During this process acetic acid joins a four carbon acceptor molecule to form a six-carbon product called citric acid. For every acetic acid that enters the cycle as fuel two CO2 molecules eventually exit as a waste product. As this process continues citric acid harvests energy from the fuel.

Some of this energy is used to produce ATP directly, but the cycle captures much more energy in the form of NADH and FADH. All the carbon atoms that entered the cycle as fuel are accounted for as CO2 exhaust, and the four-carbon acceptor molecule is recycled. The citric acid cycle turns twice for every glucose molecule that fuels a cell. •What is the role of the electron transport system? Include the reactants and the products. Where does it occur? The electron transport chain functions as a chemical machine that uses the energy released by the “fall” of electrons to pump hydrogen ions across the inner mitochondrial membrane.

The pumping causes ions to become more concentrated on one side of the membrane than the other, thus storing potential energy. NADH and FADH2 transfer electrons to an electron transport chain. It uses this energy supply to pump H+ across the inner mitochondrial membrane. Oxygen pulls electrons down the transport chain. The H+ concentrated on one side of the membrane rushes back “downhill” through an ATP synthase. This action spins a component of the ATP synthase, just as water turns the turbines in a dam.

The rotation activates parts of the synthase molecule to generate ATP. Photosynthesis: •What is the overall goal of photosynthesis? Photosynthesis is a process whereby plants, algae, and certain bacteria transform light energy into chemical energy, using carbon dioxide and water as starting materials. •Because photosynthesis only occurs in plants, why is it essential to animal life? Photosynthesis is essential to animal life because it produces oxygen for them to breath, and food for them to eat. •What is the role of the light reactions?

Include the reactants and the products. Where does it occur? During the light reactions water is split, providing a source of electrons and giving off O2 gas as a by-product. •What is the role of the Calvin cycle? Include the reactants and the products. Where does it occur? The Calvin cycle uses the products of the light reactions to power the production of sugar from carbon dioxide. The enzymes are dissolved in the stroma. ATP generated by the light reactions provides the energy for sugar synthesis.

The NADPH produced by the light reactions provides the high-energy electrons for the reductions for carbon dioxide to glucose. Summary: •Explain how photosynthesis and cellular respiration are linked within ecosystems. Photosynthesis and cellular respiration are linked within the eco systems because the whole process helps the eco system. Photosynthesis and cellular respiration produces oxygen that animals and humans need to breath. Plants are also a source of food for many animals and humans. •Visit the NASA website (http://data. giss. nasa. ov/gistemp/graphs/) and research global temperature changes. How has global warming affected overall temperatures? What effects do cellular respiration and photosynthesis have on global warming? According to the charts it seems as though over the past years that the temperature has done nothing go up. Global warming decreases the productivity of cellular respiration and photosynthesis because the heat would throw off the cycles. Bibliography Simon, E. J. , Reece, J. B. , & Dickey, J. L. (2010). Campbell Essential Biology with Physiology. San Francisco: Pearson Education, Inc.