CHAPTER 4: CELLS AND ENERGY



CHAPTER 4: CELLS AND ENERGY

RESOURCES

Student Edition Labs

Rates of Photosynthesis p. 106-107

Fermentation p. 124

Options for Inquiry

Cellular Respiration p. 126

Investigate Fermentation in Food p. 127

Lab Binder

Additional Investigation p. 23-28

Vernier Probeware Lab: Photosynthesis and Respiration p. 59-61

The Effect of Temperature on Respiration p. 79-82

Power Presentations

Chapter 4

Media Gallery

ATP-ADP Interaction

Cellular Energy

Weightlifter

Volvox

Power Notes

Video

View a short video clip exploring fermentation

Animated Biology

Photosynthesis

Cellular Respiration

Mirror Processes

Transparencies

ATP and ADP T18

Photosynthesis T19

Light-Dependent Reactions T20

The Calvin Cycle T21

Cellular Respiration T22

The Krebs Cycle T23

The Electron Transport Chain T24

Fermentation T25



4.1: Chemical Energy and ATP

Objectives: Recognize the importance of ATP as an energy carrying molecule.

Identify energy sources used by organisms.

Warm Up: Would you rather have fifty $1 bills or one $50 bill?

Words to Know: ATP, ADP, Chemosynthesis

The Chemical Energy Used for Most Cell Processes is Carried by ATP

• Carbohydrates and lipids are the most important energy sources in food you eat.

• This energy is only usable after these molecules are broken down by a series of chemical reactions.

• All cells use chemical energy carried by ATP – Adenosine Triphosphate.

• ATP is a molecule that transfers energy from the breakdown of food molecules to cell processes.

• ATP carries chemical energy that cells can use.

• Cells use ATP for functions such as building molecules and moving materials by active transport.

• The energy from ATP is released when a phosphate group is removed.

• ATP has three phosphate groups but the third bond is not as strong.

• When the phosphate group is removed, energy is released and ADP (adenosine diphosphate) is formed.

• ADP is a lower-energy molecule that can be converted into ATP by the addition of a phosphate group.

Describe the relationship between energy stored in food and ATP.

Organisms Break Down Carbon-Based Molecules to Produce ATP

• Foods that you eat do not contain ATP.

• First the food must be digested, then those molecules are used to make ATP.

• The number of ATP molecules that are made from the breakdown of food is related to the number of calories in the food.

• Carbohydrates are not stored in large amounts in the body, but hey are the molecules most commonly broken down to make ATP.

• The breakdown of the glucose makes about 36 molecules of ATP.

• Lipids actually store the about 80% of the energy in your body.

• One triglyceride can be broken down and converted into 146 molecules of ATP.

• Proteins can be used if needed, but it is not efficient.

How do lipids and carbohydrates differ in ATP production?

A Few Types of Organisms do Not Need Sunlight and Photosynthesis as a Source of Energy

• Most organisms rely directly or indirectly on sunlight and photosynthesis as their source of energy.

• Some organisms do not need sunlight.

• Chemosynthesis is a process by which some organisms use chemical energy instead of light energy to make energy storing carbon-based molecules.

• These organisms still require ATP for energy.

How are chemosynthetic organisms and plants similar as energy sources?

4.1: Assessment p. 102 (1-6)

4.2: Overview of Photosynthesis

Objectives: Relate producers to photosynthesis.

Describe the process of photosynthesis.

Warm Up: What do producers do who work in film, radio, television and music recording? What law says that energy can be transformed but never created or destroyed?

Words to Know: Photosynthesis, Chlorophyll, Thylakoid, Light-Dependent Reactions, Light-Independent Reactions.

Photosynthetic Organisms are Producers

• Producers are the source of energy for themselves and for other organisms.

• Plants, some bacteria, and protists like algae, are all producers.

• Photosynthesis is a process that captures energy from sunlight to make sugars that store chemical energy.

• Plants absorb visible light for photosynthesis.

• Chlorophyll is a molecule in chloroplasts that absorbs some of the energy in visible light.

• Plants have two main types of chlorophyll, called chlorophyll a and chlorophyll b.

• Together these two absorb mostly red and blue wavelengths of light.

• The green color of plants comes from the reflection of light’s green wavelengths by chlorophyll.

Describe the importance of producers and photosynthesis.

Photosynthesis in plants occurs in Chloroplasts

• Chloroplasts are the membrane-bound organelles where photosynthesis takes place in plants.

• Most chloroplasts are found in leaf cells.

• The two main parts of chloroplasts needed for photosynthesis are the grana and the stroma.

• Grana are stack of coin-shaped membrane enclosed compartments called Thylakoids.

• The membrane of the Thylakoids contains chlorophyll.

• The Stroma is the fluid that surrounds the grana inside the chloroplast.

• Photosynthesis has two main stages:

• The Light-Dependent Reactions

• The Light-Independent Reactions

Light-Dependent Reactions

• Light dependent reactions capture energy from sunlight.

• They take place in the membrane of the Thylakoids.

• Water and sunlight are needed for this stage of photosynthesis.

• 1. Chlorophyll absorbs energy from sunlight. The energy is transferred along the thylakoid membrane. H2O molecules are broken down. Oxygen (O2) molecules are released.

• 2. Energy carried along the thylakoid membrane is transferred to molecules that carry energy; such as ATP.

Light-Independent Reactions

• The light-independent reactions use energy from the light-dependent reactions to make sugars.

• This takes place in the stroma.

• Carbon Dioxide molecules (CO2) are needed during this stage of photosynthesis.

• 3. CO2 is added to a cycle of chemical reactions to build larger molecules. Energy from the light-dependent reactions is used in the reactions.

• 4. A molecule of simple sugar is formed. The sugar, usually glucose (C6H12O6), stores some of the energy that was captured from sunlight.

• The equation for Photosynthesis is:

• 6CO2 + 6H2O (((((( C6H12O6 + 6O2

• Carbon Dioxide Water Glucose Oxygen

How is energy from sunlight used to make sugar molecules?

4.2 Assessment p. 105 (1-5)

Rates of Photosynthesis p. 106-107.

4.3: Photosynthesis in Detail

Objectives: Describe the light-dependent reactions in which energy is captured.

Describe the light-independent reactions in which sugar is produced.

Words to Know: Photosystem, Electron Transport Chain, ATP Synthase, Calving Cycle

The First Stage of Photosynthesis Captures and Transfers Energy

• The Light Dependent Reactions are made up of Photosystem II and Photosystem I.

Overview of the Light-Dependent Reactions

• The light-dependent reactions are the photo- part of photosynthesis.

• During this reaction, chlorophyll captures energy from sunlight, water is broken down into hydrogen ions, electrons, and oxygen gas.

• Sugars are NOT made during this part.

• The main function of these reactions is to capture and transfer energy.

Photosystem II and Electron Transport

• 1. Energy Absorbed from Sunlight. Chlorophyll and other light-absorbing molecules in the thylakoid membrane absorb energy from sunlight.

• 2. Water molecules Split. Enzymes break down water molecules. The oxygen is released as waste. The electrons from water replace those electrons that left chlorophyll when energy from sunlight was absorbed.

• 3. Hydrogen Ions Transported. Electrons move from protein to protein in the electron transport chain. Their energy is used to pump H+ ions from outside to inside the thylakoid against a concentration gradient. The H+ ions build up inside the thylakoid. Electrons move to Photosystem I.

Photosystem I and Energy-Carrying Molecules

• In Photosystem I, chlorophyll and other light-absorbing molecules in the thylakoid membrane also absorb energy from sunlight.

• The energy is added to electrons.

• 4. Energy absorbed from sunlight. Electrons are energized in the thylakoid membrane.

• 5. NADPH Produced. The energized electrons are added to a molecule called NADP+, which function like ADP. A molecule called NADPH is made. The molecules of NADPH go to the light-independent reactions.

ATP Production

• The final part of the light-dependent reactions make ATP.

• 6. Hydrogen Ions Diffuse. Hydrogen ions flow through a protein channel in the thylakoid membrane.

• 7. ATP produced. The protein channel is a part of the enzyme ATP Synthase. As the ions flow through the channel, ATP Synthase makes ATP by adding phosphates to ADP.

Summary of the Light-Dependent Reactions

• Energy is captured from sunlight by light-absorbing molecules. The energy is transferred to electrons that enter an electron transport chain.

• Water molecules are broken down into H+ ions, electrons, and oxygen molecules. The water molecules provide the H+ ions and electrons that are used in the light-dependent reactions.

• Energized electrons have two functions. They provide energy for H+ ion transport, and they are added to NADP+ to form NADPH.

• The flow of H+ ions through ATP synthase makes ATP.

• The products are oxygen, NADPH, and ATP. Oxygen is given off as a waste product. Energy from ATP and NADPH is used later to make sugars.

Describe how energy from sunlight is transferred to ATP and NADPH

The Second Stage of Photosynthesis uses Energy from the First Stage to Make Sugars.

The Calvin Cycle

• The chemical reactions of the Calvin Cycle use carbon dioxide (CO2) gas from the atmosphere and the energy carried by ATP and NADPH to make simple sugars.

• Only one molecule of CO2 is added to the Calvin Cycle at a time.

• 1. Carbon dioxide added. CO2 molecules are added to five-carbon molecules already in the Calvin cycle. Six-carbon molecules are formed.

• 2. Three-carbon molecules formed. Energy—ATP and NADPH—from the light-dependent reactions is used by enzymes to split the six-carbon molecules. Three-carbon molecules are formed and rearranged.

• 3. Three-carbon molecules exit. Most of the three-carbon molecules stay in the Calvin cycle, but one high-energy three-carbon molecule leaves the cycle. After two three-carbon molecules have left the cycle, they are bonded together to build a six-carbon sugar molecule such as glucose.

• Three-carbon molecules recycled Energy from ATP molecules is used to change the three-carbon molecules back into five-carbon molecules. The five-carbon molecules stay in the Calvin cycle. These molecules are added to new CO2 molecules that enter the cycle.

Summary of the Light-Independent Reactions

• Carbon dioxide enters the Calvin cycle.

• ATP and NADPH from the light-dependent reactions transfer energy to the Calvin cycle and keep the cycle going.

• One high-energy three-carbon molecule is made for every three molecules of carbon dioxide that enter the cycle.

• Two high-energy three-carbon molecules are bonded together to make a sugar. Therefore, six molecules of carbon dioxide must be added to the Calvin cycle to make one six-carbon sugar.

• The products are a six-carbon sugar such as glucose, NADP+, and ADP. The NADP+ and ADP molecules return to the light-dependent reactions.

Functions of Photosynthesis

• Photosynthesis provides food for plants.

• Plants provide food for other organisms.

• Photosynthesis provides the raw materials for cellular respiration which creates energy.

How does the Calvin Cycle build sugar molecules?

4.3 Assessment p. 112 (1-5)

4.4: Overview of Cellular Respiration

Objectives: Describe the process of cellular respiration.

Compare cellular respiration to photosynthesis.

Warm Up: Why is breathing vital to life? How is the air you breathe in different from the air you breath out?

Words to Know: Cellular Respiration, Aerobic, Glycolysis, Anaerobic, Krebs Cycle

Cellular Respiration Makes ATP by Breaking Down Sugars

• Cellular Respiration releases chemical energy from sugars and other carbon-based molecules to make ATP, when oxygen is present.

• Cellular Respiration is an Aerobic process, which means it needs oxygen to take place.

• Cellular Respiration takes place in the mitochondria.

• The mitochondria is often called the powerhouse of the cell since this is where ATP is made.

• Before ATP can be made in mitochondria, glucose must first be broken down.

• Glycolysis splits glucose into 2 three-carbon molecules and makes 2 molecules of ATP.

• Glycolysis takes place in the cytoplasm and does NOT require oxygen.

• Processes not requiring oxygen are called Anaerobic (without oxygen).

Cellular Respiration is Like a Mirror Image of Photosynthesis

• Photosynthesis absorbs solar energy and creates glucose.

• Respiration takes in glucose and creates energy.

Krebs Cycle

• The Krebs Cycle produces molecules that carry energy to the second part of cellular respiration.

• The Krebs Cycle takes place in the interior space, or matrix of the mitochondrion.

• 1. Three-carbon molecules from glycolysis are broken down in a cycle of chemical reactions. A small number of ATP molecules are made. Other types of energy-carrying molecules are also made. Carbon dioxide is given off as a waste product.

• 2. Energy is transferred to the second stage of cellular respiration.

• An electron transport chain made of proteins needs energy-carrying molecules from the Krebs cycle and oxygen to make ATP. This part of the process takes place in and across the inner mitochondrial membrane.

• 3. Energy is transferred to a chain of proteins in the inner membrane of the mitochondrion.

• 4. A large number of ATP molecules are made. Oxygen enters the process and is used to make water molecules. Water and heat are given off as waste products.

• Up to 38 ATP molecules can be made during this process – 2 from glycolysis and 34-36 from respiration.

• The cellular respiration equation is:

• C6H12O6 + 6O2 (((((( 6CO2 + 6H2O

Glucose Oxygen Carbon Dioxide Water

Does glucose actually react with oxygen during cellular respiration? Explain

4.4 Assessment p. 115 (1-5)

Data Analysis Interpreting Graphs: Photosynthesis and Plants p. 116

4.5 Cellular Respiration in Detail

Objectives: Describe the process of glycolysis.

Describe the details of the Krebs Cycle and the Electron Transport Chain

Words to Know: Same as 4.4

Glycolysis is Needed for Cellular Respiration

• Glycolysis can be summarized as follows:

• Two ATP molecules are used to energize a glucose molecule. The glucose molecule is split into two three-carbon molecules. A series of enzymes and chemical reactions rearranges the three-carbon molecules.

• Energized electrons from the three-carbon molecules are transferred to molecules of NAD+. Molecules of NADH are formed. A series of reactions converts the three-carbon molecules to pyruvate, which enters cellular respiration. Four ATP molecules are made.

• Although glycolysis makes 4 ATP, 2 are recycled to run the next cycle of glycolysis, so the net is 2 ATP.

How does glycolysis result in a net gain of two ATP molecules?

The Krebs Cycle is the First Main part of Cellular Respiration

• 1. Pyruvate is broken down.

• 2. Coenzyme A bond to the two-carbon molecule for transport.

• 3. Citric Acid is formed in the citric acid cycle.

• 4. Citric Acid is broken down.

• 5. The five-carbon molecule formed from the breakdown of citric acid is broken down.

• 6. Four-carbon molecules are rearranged to release high energy electrons from the Krebs Cycle.

• The Products from the breakdown of one molecule of pyruvate are:

• 1. 3 molecules of carbon dioxide given off as waste.

• 2. 1 molecule of ATP

• 3. 4 molecules of NADH to the electron transport chain.

• 4. 1 molecule of FADH2 to the electron transport chain.

In what two ways is the Krebs cycle important for making ATP?

The Electron Transport Chain is the Second Main Part of Cellular Respiration.

• The ETC has for major steps.

• 1. Electrons are removed from NADH and FADH2.

• 2. Hydrogen ions are transported across the inner membrane.

• 3. ATP is produced.

• 4. Water is formed and released as waste.

• The products of Cellular Respiration including Glycolysis are:

• 1. CO2

• 2. Water

• 3. A net gain of 38 ATP.

Comparing Photosynthesis and Respiration

| |PHOTOSYNTHESIS |RESPIRATION |

|Organelle for Process |Chloroplast |Mitochondria |

|Reactants |CO2 and H2O |Sugars (C6H12O6) and O2 |

|Electron Transport Chain |Proteins within thylakoid membrane |Proteins within mitochondrial membranes |

|Cycle of Chemical Reactions |Calvin cycle in stroma, builds sugar |Krebs cycle in matrix of mitochondria breaks down sugars. |

|Products |Sugars (C6H12O6) and O2 |CO2 and H2O |

How does the electron transport chain depend on the Krebs Cycle?

4.5 Assessment p. 121 (1-5)

4.6 Fermentation

Objectives: Describe the process of fermentation.

Summarize the importance of fermentation.

Warm Up: How do long-distance runners, such as marathoners, provide the energy their bodies need for a race? What has happened to a runner who “hits the wall”?

Words to Know: Fermentation, Lactic Acid

Fermentation Allows Glycolysis to Continue

• Fermentation does not make ATP, but it allows glycolysis to continue.

• Fermentation removes electrons from NADH molecules and recycles NADP+ molecules for glycolysis.

• There are two types of fermentation:

• 1. Lactic Acid Fermentation occurs in your muscles cells when they do not get enough oxygen.

• Lactic Acid is what causes your muscles to burn during hard exercise.

• Lactic acid fermentation creates 2 ATP to be reused in glycolysis and lactic acid.

• 2. Alcohol Fermentation is used by many to create food and drinks.

• Alcohol Fermentation creates to ATP to be reused in glycolysis and 2 alcohol as a byproduct.

• Alcohol Fermentation is used to make everything from beer, to cheese, to yogurt, to bread.

Quick Lab: Fermentation p. 124

Explain the importance of alcoholic fermentation in the production fo bread’s light, fluffy texture.

4.6 Assessment p. 125 (1-4)

Options for Inquiry: Cellular Respiration p. 126-127

Online Virtual Lab ()

Animated Biology ()

Interactive Review ()

Chapter Assessment p.129-131

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