Process of Photosynthesis and Cellular Respiration.

Photosynthesis Vs Cellular Respiration

Plants, algae, and some bacteria use photosynthesis to turn sunlight into complex organic molecules that store energy. Then they metabolize those molecules via cellular respiration to get the energy they need for their own growth and activities.

Cellular respiration consists of three unique metabolic pathways – glycolysis, the citric acid cycle, and the electron transport chain. Each pathway produces a small amount of the energy-giving molecule ATP.


Photosynthesis is the process by which plants and some bacteria use sunlight to convert carbon dioxide and water into carbohydrates and oxygen. It is the only process that can produce energy from light, and it accounts for most of the energy in the atmosphere.

It occurs in the chloroplast, a specialized organelle that contains the pigment chlorophyll. Sunlight hits chlorophyll and energizes electrons, which are used to form covalent bonds in the sugar molecules that result from photosynthesis. The energy from these covalent bonds is stored in the form of adenosine triphosphate (ATP).

Cellular respiration uses this energy to break down the glucose that results from photosynthesis. It also produces carbon dioxide and water. Glycolysis, the Krebs cycle and oxidative phosphorylation are all part of cellular respiration. The energy from these processes is absorbed as ATP, but some of it is lost as heat during the process.

Cellular Respiration

Cellular respiration is a series of reactions and processes that convert biochemical energy stored in molecules like glucose into ATP. ATP is used by cells to power cellular processes such as growth, movement, and the transport of molecules across cell membranes.

The first stage of cellular respiration is glycolysis which breaks down a glucose molecule into two pyruvic acid molecules and four ATP molecules. Glycolysis takes place in prokaryotic cells as well as the cytoplasm and mitochondria of eukaryotic cells. This step of cellular respiration does not require oxygen and is called anaerobic.

Cellular respiration also includes the Krebs cycle and oxidative phosphorylation. Oxidative phosphorylation is when the electrons from pyruvic acid are transferred to NADP and then to another molecule like adenosine triphosphate (ATP). This process requires oxygen and is called aerobic. Cellular respiration is a universal process that all living organisms use to obtain energy.


Glycolysis is the first step of cellular respiration. This anaerobic process takes place in the cytoplasm of cells, which is the jelly-like substance filling a plant or animal cell. Glycolysis splits a glucose molecule into two three-carbon molecules called pyruvate. These molecules are then fed into the citric acid cycle, which generates 32 ATP molecules for each molecule of glucose.

The ATP molecules produced by glycolysis have a very short lifespan, and so the cell must turn them into carbohydrate molecules for long-term energy storage. A molecule of carbon dioxide is needed to do this. During the light-independent reactions, which are part of photosynthesis, an enzyme known as RuBisCo combines a carbon dioxide molecule with a simple carbohydrate molecule to form glyceraldehyde-3-phosphate (G3P).

This is the raw material that will become glucose in the light-dependent reaction. In addition, the G3P can also be used to build other sugar molecules and other organic compounds that provide vital energy for living things.


Cellular respiration is where the energy that was made in photosynthesis is chowd down on. This is a catabolic process where glucose molecules are broken down for the production of ATP, FADH2, and NADH. This also releases oxygen and water.

To do this, a cycle of reactions occurs where protons are pumped across the mitochondrial membrane. This creates an electrical gradient that is powered by a enzyme called ATP synthase. During this process, molecules of adenosine diphosphate (ADP) are turned into ATP by adding a third phosphate group. This is called oxidative phosphorylation.

Photosynthesis happens inside green plastids in plant cells and is like the cell’s power plant. Cellular respiration is where the energy of complex food molecules in plants and animals is converted to adenosine triphosphate, or ATP. ATP is used in cellular functions and to move muscles. It provides us with the energy we need to continue living. Without it, our bodies would die.

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