Cell Processes Key Concepts • Explain how the sun supplies living things with the energy they need. • Describe what happens during the process of photosynthesis. • Describe the events that occur during respiration. • Tell what fermentation is. Key Terms • Photosynthesis • The process by which a cell captures energy in sunlight and uses it to make food. • Autotroph • An organism that makes its own food. • Heterotroph • An organism that cannot make its own food. • Pigment • Colored chemical compounds that absorb light. Key Terms • Chlorophyll • The main photosynthetic pigment in chloroplasts. • Stomata • Small openings in the undersides of leaves where CO2 enters and O2 exits. • Respiration • The process by which cells obtain energy from glucose. • Fermentation • An energy-releasing process that does not require oxygen. Introduction • Every living thing needs energy. • All cells need energy to carry out their functions. – Making proteins – Transporting substances into and out of the cell • The sun supplies energy for most living things, directly or indirectly. Sources of Energy • Autotroph • Heterotroph • An organism that makes its own food. • An organism that cannot make its own food. • Ex. plants, algae, some bacteria • Ex. animals, fungi, some bacteria Photosynthesis What is Photosynthesis? • The process by which a cell captures energy in sunlight and uses it to make food. • Photo – light • Synthesis – putting together Two Stages of Photosynthesis • Capturing the Sun’s Energy. • Using Energy to Make Food. Stage 1: Capturing the Sun’s Energy • In plants, this energy-capturing process occurs mostly in the leaves. • Chloroplasts, containing chlorophyll, capture energy from sunlight. Stage 2: Using Energy to Make Food • The cell uses the captured energy to produce sugars. • Water and Carbon Dioxide (raw materials) are needed for this stage. • The raw materials undergo a complex series of chemical reactions producing sugar and oxygen. Animation of Photosynthesis • http://www.growingthenextgeneration.com/ag rium-games/Animation/index.htm The Chemical Equation for Photosynthesis Simplifying the Equation • Raw Materials – Water & Carbon Dioxide • Catalyst – Light Energy • Products – Carbohydrates (Sugars) & Oxygen Respiration What is Respiration? • The process by which cells obtain energy from glucose. • Cells break down simple food molecules such as sugar and release the energy they obtain. Breathing and Respiration • Respiration has two meanings. – “Breathing” – moving air in and out of your lungs. – “Cellular Respiration” – respiration process that takes place inside cells. • The connection – “breathing” brings oxygen into the body needed for “cellular respiration” to occur. Two Stages of Respiration • Breaking down glucose. • Breaking down glucose even more. Stage 1: Breaking Down Glucose Molecules • This first stage takes place in the cytoplasm of the organism’s cells. • Oxygen is not involved in this part of the process and only a small amount of energy is released. Stage 2: Making Small Glucose Molecules Smaller • This second stage takes place in the mitochondria of the organism’s cells. • Oxygen is required in these chemical reactions and a great deal of energy is released. Animation of Respiration • http://www.sumanasinc.com/webcontent/anima tions/content/cellularrespiration.html • Click on “The Big Picture”. (You can add subtitles!) The Chemical Equation for Respiration Simplifying the Equation • Raw Materials – Glucose & Oxygen • Catalyst – Stored Energy • Products – Carbon Dioxide, Water & Energy (ATP) What’s the Connection? Photosynthesis and Respiration are Opposites Fermentation What is Fermentation? • Respiration without oxygen! Fermentation Defined • An energy-releasing process that does not require oxygen. • Some single-celled organisms live where there is no oxygen, such as deep in the ocean or in the mud of lakes or swamps. • The amount of energy released from each sugar molecule is much lower than the amount released during respiration (with oxygen). Types of Fermentation • Alcoholic • Lactic Acid Alcoholic Fermentation • Yeast and other single-celled organisms break down sugars. • This is often called alcoholic fermentation because alcohol is one of the products. • Carbon dioxide and a small amount of energy are also products. Carbon dioxide in yeast causes bread to rise and causes the bubbles in alcoholic drinks like beer and wine. Lactic Acid Fermentation • Takes place at times in your body. • Muscle cells use up oxygen faster than it can be replaced. • When cells lack oxygen, fermentation occurs. • Lactic acid is a product of fermentation within animal cells. – painful sensation in your muscles – muscles feel weak and sore Photosynthesis and Respiration Cell processes that affect the function of the entire organism.