Energy Energy

Energy Learning Objectives Define autotroph and heterotroph Explain the use of energy-carrier molecules such as ATP Compare and contrast photosynthesis and respiration After this lesson you will be able to define autotroph and heterotroph, explain the use of energy-carrier molecules such as ATP, and compare and contrast photosynthesis and respiration.  

Obtaining Energy A plant placed in a dark closet may die within days. Some animals, such as the Kret mole, spend their lives in relative darkness. A squirrel forages for nuts in the winter and then remains mostly in the dark while hibernating. Why do most plants in the dark quickly die while some animals can survive? The answer lies in the way organisms obtain energy.

Energy Flows through ecosystems Originates from sun Transferred between organisms Leaves ecosystem as motion and heat Energy flows through ecosystems. Most energy originates from the sun, is transferred between organisms, and then leaves the ecosystem as motion and heat. Without input from the sun and other sources, the flow of energy would stop.

Autotrophs & Heterotrophs Autotrophs – capture energy they need from environment and store it in chemical bonds of molecules (glucose) Photosynthesis – sunlight Chemosynthesis Heterotrophs – acquire energy by consuming other organisms Some organisms, such as trees, can capture the energy they need from their environment and store it in the chemical bonds of molecules, such as glucose. These types of organisms are autotrophs. There are two main types of autotrophs: those that use photosynthesis to capture energy from sunlight (plants and some bacteria) and those that use chemosynthesis. Other organisms, such as elk, acquire energy by consuming other organisms. These types of organisms are heterotrophs.  

Autotrophs & Heterotrophs Chemosynthetic organisms – use chemicals instead of sunlight as an energy source Bacteria and archaea Bacteria in hydrothermal vents oxidize hydrogen sulfide gas Some discovered in other ocean environments and hot springs on land Chemosynthetic organisms are a diverse group of bacteria and archaea that can use chemicals instead of sunlight as an energy source. For example, bacteria that live in darkness on the deep seafloor oxidize hydrogen sulfide gas from hydrothermal vents. These bacteria use the energy to create carbohydrate molecules. Chemosynthetic bacteria have been discovered in other ocean environments and hot springs on land. Each variety utilizes a unique chemical pathway.

ATP Organisms use chemical energy from food (carbohydrates) Break chemical bonds in carbohydrates  energy released Stored in energy-carrier molecule (ATP) Adenosine triphosphate (ATP) – 5-carbon sugar (ribose) joined to nitrogenous base (adenine) and three phosphate groups Energy flows through ecosystems. Like machines, organisms must have energy to function. While a machine may use chemical energy from gasoline, living organisms use chemical energy from food, such as carbohydrates. When living organisms break chemical bonds from carbohydrates, energy is released and stored in the form of an energy-carrier molecule. One of the most important energy-carrier molecules is adenosine triphosphate, abbreviated ATP. ATP is a 5-carbon sugar (ribose) joined to a nitrogenous base (adenine) and three phosphate groups.

ATP ATP stores energy in chemical bonds ATP  ADP Like a battery, ATP can store energy in its chemical bonds. By adding energy and a phosphate group, the molecule adenosine diphosphate (ADP) is “charged” into ATP . When water is used to break the high-energy chemical bonds between the phosphates, energy is released. Removal of one phosphate group produces energy, and ATP becomes ADP. Some chemical reactions that utilize ATP are photosynthesis, cellular respiration, and fermentation.

Photosynthesis & Respiration Photosynthesis – process by which some autotrophs capture energy from the sun Creates sugars Allows autotrophs to store solar energy Chemical equation for photosynthesis: 6CO2 + 6H2O + energy  C6H12O6 + 6O2 carbon dioxide + water + energy  glucose + oxygen Photosynthesis is the process by which some autotrophs capture energy from the sun. This process creates sugars, which can be broken down to release energy later. Therefore, photosynthesis allows these autotrophs to store solar energy for later use. In this process, carbon dioxide, solar energy, and water are used within cells to create sugars and oxygen. In plants, the sugar made is glucose. Aquatic plants use dissolved carbon dioxide in the water for photosynthesis and release the oxygen bubbles. Photosynthesis can be written as a chemical equation. Since carbon dioxide, water, and energy are used, these are the reactants. They react to make glucose and oxygen, the products. 6CO2 + 6H2O + energy  C6H12O6 + 6O2 carbon dioxide + water + energy  glucose + oxygen  

Photosynthesis & Respiration Cellular respiration – process by which living things release energy from sugars Stores energy within ATP Energy released as work and heat Energy powers cellular activities Chemical equation for respiration: C6H12O6 + 6O2  6CO2 + 6H2O + energy glucose + oxygen  carbon dioxide + water + energy Cellular respiration is the process by which living things release energy from sugars. This process stores energy within ATP. Once the cell uses it, this energy is released as work and heat. In this process, sugars and oxygen are used within cells to create carbon dioxide, energy, and water. Carbon dioxide and water are the waste products. The energy powers cellular activities, such as growth and active transport of molecules. An entire organism can move as many cells use energy. A running cheetah uses countless ATP molecules formed during cellular respiration. Even though autotrophs, such as plants, can capture energy from the sun, they must store the energy from sugars within ATP for the cell’s use. Therefore, autotrophs utilize both photosynthesis and cellular respiration. Respiration can also be written as a chemical equation. Since glucose and oxygen are used, these are the reactants. They react inside cells to make the products carbon dioxide, water, and energy.   C6H12O6 + 6O2  6CO2 + 6H2O + energy glucose + oxygen  carbon dioxide + water + energy

Photosynthesis & Respiration Only performed by autotrophs Uses solar energy to create high-energy sugars Uses carbon dioxide, water, and solar energy to create sugar and oxygen Respiration Performed by autotrophs and heterotrophs Converts energy in sugars into energy within ATP Uses sugar and oxygen to create carbon dioxide, water, and ATP Photosynthesis and cellular respiration are related, but they have many differences. Photosynthesis can only be performed by autotrophs, such as plants. Remember that heterotrophs must obtain stored energy such as sugars by consuming other organisms. All living things, both autotrophs and heterotrophs, perform respiration. Photosynthesis uses solar energy to create high-energy sugars. Respiration converts the energy in sugars into energy within ATP. As the ATP is used to do work, some of the energy is released as heat.   Photosynthesis uses carbon dioxide, water, and solar energy to create sugar and oxygen. Respiration uses sugar and oxygen to create carbon dioxide, water, and ATP.

Photosynthesis & Respiration Notice that the reactants of one process are the products of the other. While the matter cycles, the energy must be constantly added.

Energy Learning Objectives Define autotroph and heterotroph Explain the use of energy-carrier molecules such as ATP Compare and contrast photosynthesis and respiration You should now be able to define autotroph and heterotroph, explain the use of energy-carrier molecules such as ATP, and compare and contrast photosynthesis and respiration.