Photosynthesis, Respiration, and Fermentation The Working Cell Photosynthesis, Respiration, and Fermentation

Sunlight Powers Life Autotrophs are organisms that make their own food. Autotrophs make their own food using photosynthesis. Autotrophs are also called producers because they produce the organic molecules that serve as the food for other organisms in their ecosystem. Heterotrophs cannot make their own food, so they are also called consumers.

Harvesting Energy From Food To release the energy from food heterotrophs (consumers) use cellular respiration. Cellular respiration converts glucose and oxygen into ATP. Carbon dioxide and water are produced as waste products. The products of photosynthesis are the reactants for cellular respiration.

Food Stores Chemical Energy Food has chemical energy. The organic molecules inside foods are digested and absorbed into cells. The digested foods fuel the cellular respiration. Cellular respiration occurs in the mitochondria and makes ATP.

Putting Chemical Energy to work Organic molecules are high in chemical energy. The heat generated from cellular respiration helps maintains body temperature. When you exercise your body heats up because cellular respiration rates increase to meet the higher energy needs.

ATP provides energy for cellular work ATP stands for “Adenosine Triphosphate”. Adenosine is made of adenine and ribose. Three phosphate molecules form a tail. When a phosphate is removed, chemical energy is released (Adenosine Diphosphate) ATP → ADP + P

The energy in ATP drives three types of cellular work. ATP and Cellular Work The energy in ATP drives three types of cellular work. Many process in cells need energy. Chemical Work: Building large molecules Mechanical Work: Moving muscle proteins Transport Work: Moving solutes across membranes.

The ATP cycle ATP is continuously converted to ADP as cells do work. ADP can be recharged into ATP by adding a phosphate The energy to recharge ADP into ATP comes from your food.

Cellular Respiration occurs in the mitochondria This process occurs in the mitochondria of each cell. Cells that need lots of energy have lots of mitochondria. When we exercise, our mitochondria need more oxygen and produce more carbon dioxide. That’s why we breathe faster!

Harvesting Energy without Oxygen Fermentation makes energy without oxygen. Fermentation in muscles produces lactic acid. If yeast is kept in an anaerobic environment, they produce ethyl alcohol. Breads, beer and wine use the carbon dioxide to make bubbles.

Photosynthesis uses light Energy to make food Plants have chloroplasts in their cells. Chloroplasts contain chlorophyll. Chlorophyll makes leaves green.

Overview of photosynthesis Chlorophyll absorbs light energy from the sun. Plants take in water from roots and carbon dioxide in the air. Using the light energy new chemical bonds are formed, producing carbohydrates.

Carbon Cycle The carbon cycle is dependent on the chemical reaction occurring in chloroplasts and mitochondria. Producers pull carbon dioxide from the air and convert it to carbohydrates. Consumers eat plants and absorb the energy while releasing carbon dioxide into the air.

Photosynthesis and Global Climate Carbon dioxide is a key element in carbon cycle. Carbon dioxide in the air traps heat. The greenhouse effect helps keeps the earth’s temperature warm enough for living things. When fossil fuels are burned, more carbon dioxide is produced. This additional carbon dioxide may lead to global warming.