Cell Energy A. Van der Fluit South Gate High School 2006 Lecture Outline The purpose of this lecture is to answer three questions: • Why should I care about cell energy? • What is energy, anyway? • How do cells get energy? Why should I care about cell energy? 1st - Cells need energy to do their jobs. Without energy, you wouldn’t be able to live! - growth and development -reproduction -movement -active transport of materials 2nd - The need for energy is what connects you to other living things. So take care of these living things – without them you would die! Consider this… Just sitting in your chair right now, you are burning about 81 calories per hour. (A calorie is a unit used to measure energy). Think about the last 24 hours, and explain to your neighbor where you got the energy to do this from. What is energy? Energy is what allows things to be moved or changed. - kicking a ball makes it move - cooking an egg makes it change color Energy comes in many forms: -mechanical (gears turning in a car) -chemical (chemical bonds breaking) -light (ultraviolet radiation burning your skin) -sound (the music you listen to) -thermal (heating up food) -electrical (powering light bulbs, iPods, etc) A Few More Things About Energy • Energy can be stored, waiting to be used… – A rock at the top of a hill – A battery waiting to be used – A piece of wood waiting to be burned – Food waiting to be broken into smaller parts “POTENTIAL” energy • Energy can be in use, causing motion or change… – A rock rolling down the hill – A battery powering an iPod – A piece of wood burning – Food being broken down, releasing energy “KINETIC” energy Self-Check: Kinetic or Potential? KINETIC Self-Check: Kinetic or Potential? POTENTIAL Self-Check: Kinetic or Potential? POTENTIAL Self-Check: Kinetic or Potential? POTENTIAL Self-Check: Kinetic or Potential? KINETIC Self-Check: Kinetic or Potential? POTENTIAL Self-Check: Kinetic or Potential? POTENTIAL Self-Check: Kinetic or Potential? KINETIC How do cells get their energy? Cells use chemical energy, that’s the kind stored in chemical bonds (the electrons)… …ATP is the Energy molecule (Adenosine Tri-Phosphate) The cells break the bonds of the ATP molecule. This releases a tremendous amount of energy. The cells use this energy to do their work. Self Check: Fill In The Blanks 1. Energy is the ability to make something move change _________ or __________. 2. There are two basic forms of energy: energy potential that is stored, called ____________ energy and energy that is being used, called ____________ energy. kinetic 3. ATP is a cell’s _____________ energy. potential 4. A cell uses the energy stored in ATP by chemical bonds breaking the _________ ________ . I know what you’re wondering… Where do cells get this ATP from? Making ATP Cells make ATP using their “powerhouses”… THE MITOCHONDRION (pl. mitochondria) Cellular Respiration Mitochondria use a process known as “cellular respiration” to breakdown glucose and make ATP. C6H12O6 + O2 CO2 + H2O + 36 ATP Glucose + Oxygen Carbon Dioxide + Water + 36 ATP Cellular Respiration The process of respiration occurs in three steps: 1st – Glycolysis: Glucose is broken into two pyruvate molecules, and 2 ATP are produced. 2nd – Kreb’s Cycle: each pyruvate is broken into two carbon dioxide molecules, 1 ATP, 3 NADH and 1 FADH2. 3rd – Oxidative Respiration: the electron transport chain uses the NADH and FADH2 to make 32 ATP. Self Check: True or False? T/F 1. Mitochondria use water, oxygen and carbon dioxide to make ATP. T/F 2. Cellular respiration is the process used by mitochondria to produce energy for the cell. T/F 3. The three stages of cellular respiration are glycolysis, kreb’s cycle and oxidative respiration. T/F 4. Cells need glucose to make ATP. T/F 5. Without oxygen, ATP can’t be made. C6H12O6 + O2 CO2 + H2O + 36 ATP ATP without Oxygen When oxygen is present, cellular respiration occurs as described; “aerobic” respiration. When oxygen is absent, cellular respiration switches to “anaerobic” respiration, or “fermentation”. Fermentation There are two forms of fermentation: Lactic acid fermentation: ATP and lactic acid are produced and builds up, causing cramps! Alcoholic fermentation: ATP and ethyl alcohol are produced; cheers! Self Check: Short Answer 1. What are the two forms of fermentation? Lactic acid fermentation, alcoholic fermentation 2. What is the purpose of fermentation? To make ATP when there is no oxygen 3. What is the essential ingredient for any form of respiration? C6H12O6 + O2 CO2 + H2O + 36 ATP Glucose I know what you’re thinking… Where do cells get their glucose from? Well, it depends on whether the organism is an… Autotroph or a… Heterotroph Autotrophs make their own glucose • All plants • Some Protists • Some Bacteria Heterotrophs ingest their glucose • All animals • All fungi It all starts with the Autotrophs Heterotrophs may eat other heterotrophs, but ultimately, all glucose comes from an autotroph. Autotroph or Heterotroph? HETEROTROPH Autotroph or Heterotroph? AUTOTROPH Autotroph or Heterotroph? HETEROTROPH Autotroph or Heterotroph? AUTOTROPH Autotroph or Heterotroph? HETEROTROPH Autotroph or Heterotroph? AUTOTROPH I know what you’re thinking… How do autotrophs make their own glucose? Glucose It’s all about chlorophyll… Chlorophyll is a green pigment that absorbs sunlight and gets “excited”! Eukaryotes keep their chlorophyll in their chloroplasts. Prokaryotes keep it in their cytoplasm. Making glucose Autotroph cells make glucose using their “solar- powered glucose factories”… THE CHLOROPLASTS Photosynthesis Chloroplasts use a process known as “photosynthesis” to make glucose from carbon dioxide, water and sunlight. CO2 + H2O + SUNLIGHT C6H12O6 + O2 Carbon Dioxide + Water + SUNLIGHT Glucose + Oxygen Photosynthesis Photosynthesis also takes place in two steps: 1st – Photophosphorylation: Chlorophyll captures light energy and uses it to make ATP and NADPH. *because this step requires sunlight, it is also called the “Light Reaction”. 2nd – The Calvin Cycle: The ATP and NADPH are used to combine 6 carbon dioxide molecules to form one glucose molecule. *because this step does not require sunlight, it is also called the “Dark Reaction”. Self Check: Fill In The Blanks 1. Autotrophs use _____________ to make their photosynthesis glucose. water 2. Photosynthesis requires ___________, ________ ________ and ____________. carbon dioxide sunlight 3. The two steps of photosynthesis are the Calvin cycle __________________ and ______________. photophosphorylation 4. _____________ is the green pigment used to Chlorophyll capture light energy from the sun. 5. The purpose of the light reactions is to make ___________ and ________ for the dark ATP NADPH reactions. Consider this… In nature, all organisms and processes are intimately connected to each other… …how are respiration and photosynthesis connected to each other? The Yin and Yang of Cell Energy C6H12O6 + O2 CO2 + H2O + 36 ATP Respiration requires …and respiration oxygen… produces carbon dioxide! Photosynthesis …and photosynthesis requires carbon dioxide… produces oxygen! CO2 + H2O + SUNLIGHT C6H12O6 + O2 In Summary Remember… - Cells need energy. - Cells use ATP as their source of energy. - Cellular respiration uses glucose to make ATP. - Photosynthesis uses sunlight to make glucose. - The two processes are intimately connected.