Chapter 5. Table of Contents. Section 1 Energy and Living Things. Section 2 Photosynthesis. Section 3 Cellular Respiration

Transcription

1 Photosynthesis and Cellular Respiration Table of Contents Section 1 Energy and Living Things Section 2 Photosynthesis Section 3 Cellular Respiration

2 Section 1 Energy and Living Things Objectives Analyze the flow of energy through living systems. Compare the metabolism of autotrophs with that of heterotrophs. Describe the role of ATP in metabolism. Describe how energy is released from ATP.

3 Section 1 Energy and Living Things Energy in Living Systems Directly or indirectly, almost all of the energy in living systems needed for metabolism comes from the sun.

4 Section 1 Energy and Living Things Energy in Living Systems, continued Building Molecules That Store Energy Metabolism involves either using energy to build molecules or breaking down molecules in which energy is stored. Photosynthesis is the process by which light energy is converted to chemical energy. Organisms that use energy from sunlight or from chemical bonds in inorganic substances to make organic compounds are called autotrophs.

5 Section 1 Energy and Living Things Energy in Living Systems, continued Breaking Down Food for Energy The chemical energy in organic compounds can be transferred to other organic compounds or to organisms that consume food. Organisms that must get energy from food instead of directly from sunlight or inorganic substances are called Heterotrophs. Cellular respiration is a metabolic process similar to burning fuel.

6 Section 1 Energy and Living Things Comparing Autotrophs and Heterotrophs

7 Section 1 Energy and Living Things Energy in Living Systems, continued Transfer of Energy to ATP When cells break down food molecules, some of the energy in the molecules is released as heat. Much of the remaining energy is stored temporarily in molecules of ATP. Like money, ATP is a portable form of energy currency inside cells. ATP delivers energy wherever energy is needed in a cell.

8 Section 1 Energy and Living Things Breakdown of Starch

9 Section 1 Energy and Living Things ATP ATP (adenosine triphosphate) is a nucleotide with two extra energy-storing phosphate groups. Energy is released when the bonds that hold the phosphate groups together are broken. The removal of a phosphate group from ATP produces adenosine diphosphate, or ADP: H 2 O + ATP ADP + P + energy

10 Section 1 Energy and Living Things ATP Releases Energy

11 Section 1 Energy and Living Things Comparing ADP with ATP

12 Section 2 Photosynthesis Objectives Summarize how energy is captured from sunlight in the first stage of photosynthesis. Analyze the function of electron transport chains in the second stage of photosynthesis. Relate the Calvin cycle to carbon dioxide fixation in the third stage of photosynthesis. Identify three environmental factors that affect the rate of photosynthesis.

13 Section 2 Photosynthesis Using the Energy in Sunlight The Stages of Photosynthesis Stage 1 Energy is captured from sunlight. Stage 2 Light energy is converted to chemical energy, which is temporarily stored in ATP and the energy carrier molecule NADPH. Stage 3 The chemical energy stored in ATP and NADPH powers the formation of organic compounds, using carbon dioxide, CO 2.

14 Section 2 Photosynthesis Using the Energy in Sunlight The Stages of Photosynthesis Photosynthesis can be summarized by the following equation: Sunlight 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Carbon dioxide water sugars oxygen gas

15 Section 2 Photosynthesis Photosynthesis

16 Section 2 Photosynthesis Photosynthesis

17 Section 2 Photosynthesis Stage One: Absorption of Light Energy Sunlight contains a mixture of all the wavelengths (colors) of visible light. When sunlight passes through a prism, the prism separates the light into different colors.

18 Section 2 Photosynthesis Stage One: Absorption of Light Energy, continued Pigments How does a human eye or a leaf absorb light? These structures contain light-absorbing substances called pigments. Chlorophyll the primary pigment involved in photosynthesis, absorbs mostly blue and red light and reflects green and yellow light. Plants contain two types of chlorophyll, chlorophyll a and chlorophyll b.

19 Section 2 Photosynthesis Chlorophyll a and b

20 Section 2 Photosynthesis Stage One: Absorption of Light Energy, continued Pigments The pigments that produce yellow and orange fall leaf colors, as well as the colors of many fruits, vegetables, and flowers, are called carotenoids. Carotenoids absorb wavelengths of light different from those absorbed by chlorophyll, so having both pigments enables plants to absorb more light energy during photosynthesis.

21 Section 2 Photosynthesis Carotenoid

22 Section 2 Photosynthesis Spectrum of Light and Plant Pigments

23 Section 2 Photosynthesis Absorption Spectra of Photosynthetic Pigments

24 Section 2 Photosynthesis Stage One: Absorption of Light Energy, continued Production of Oxygen Clusters of pigments are embedded in the membranes of disk-shaped structures called thylakoids. When light strikes a thylakoid in a chloroplast, energy is transferred to electrons in chlorophyll. This energy transfer causes the electrons to jump to a higher energy level. This is how plants first capture energy from sunlight.

25 Section 2 Photosynthesis Stage One: Absorption of Light Energy, continued Production of Oxygen The excited electrons that leave chlorophyll molecules must be replaced by other electrons. Plants get these replacement electrons from water molecules, which are split by thylakoid. The oxygen atoms, O, from the disassembled water molecules combine to form oxygen gas, O 2.

26 Section 2 Photosynthesis Chloroplast

27 Section 2 Photosynthesis Parts of a Chloroplast

28 Section 2 Photosynthesis Stage Two: Conversion of Light Energy Excited electrons that leave chlorophyll molecules are used to produce new molecules that temporarily store chemical energy. First an excited electron jumps to a nearby molecule in the thylakoid membrane. Then the electron is passed through a series of molecules along the thylakoid membrane. The series of molecules through which excited electrons are passed along a thylakoid membrane are called electron transport chains.

29 Section 2 Photosynthesis Stage Two: Conversion of Light Energy, continued Electron Transport Chains While one electron transport chain provides energy used to make ATP, a second electron transport chain provides energy used to make NADPH. NADPH is an electron carrier that provides the high-energy electrons needed to make carbon-hydrogen bonds in the third stage of photosynthesis. In this second chain, excited electrons combine with hydrogen ions as well as an electron acceptor called NADP +, forming NADPH.

30 Section 2 Photosynthesis Electron Transport Chains of Photosynthesis

31 Section 2 Photosynthesis Electron Transport Train

32 Section 2 Photosynthesis Converting Light Energy to Chemical Energy

33 Section 2 Photosynthesis Stage Three: Storage of Energy In the third (final) stage of photosynthesis, carbon atoms from carbon dioxide in the atmosphere are used to make organic compounds in which chemical energy is stored. The transfer of carbon dioxide to organic compounds is called carbon dioxide fixation.

34 Section 2 Photosynthesis Stage Three: Storage of Energy, continued Calvin Cycle The Calvin cycle is a series of enzyme-assisted chemical reactions that produces a three-carbon sugar: Step 1 Each molecule of carbon dioxide is added to a fivecarbon compound by an enzyme. Step 2 The resulting compound splits into two three-carbon compounds. Phosphate groups and electrons are added to the compounds. Step 3 One of the resulting three-carbon sugars is used to make organic energy-storing compounds. Step 4 The other three-carbon sugars are used to regenerate the initial five-carbon compound, thereby completing the cycle.

35 Section 2 Photosynthesis Calvin Cycle

36 Section 2 Photosynthesis Calvin Cycle

37 Section 2 Photosynthesis Stage Three: Storage of Energy, continued Factors that Affect Photosynthesis Photosynthesis is directly affected by various environmental factors. In general, the rate of photosynthesis increases as light intensity increases until all the pigments are being used. Photosynthesis is most efficient within a certain range of temperatures.

38 Section 2 Photosynthesis Environmental Influences on Photosynthesis

39 Section 3 Cellular Respiration Objectives Summarize how glucose is broken down in the first stage of cellular respiration. Describe how ATP is made in the second stage of cellular respiration. Identify the role of fermentation in the second stage of cellular respiration. Evaluate the importance of oxygen in aerobic respiration.

40 Section 3 Cellular Respiration Cellular Energy Oxygen in the air you breathe makes the production of ATP more efficient, although some ATP is made without oxygen. Metabolic processes that require oxygen are called aerobic. Metabolic processes that do not require oxygen are called anaerobic, which means without air.

41 Section 3 Cellular Respiration Cellular Energy, continued The Stages of Cellular Respiration Cellular respiration is the process cells use to harvest the energy in organic compounds, particularly glucose. The breakdown of glucose during cellular respiration can be summarized by the following equation: C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + energy glucose oxygen gas carbon dioxide water ATP

42 Section 3 Cellular Respiration Cellular Energy, continued The Stages of Cellular Respiration Cellular respiration occurs in two stages: Stage 1 Glucose is converted to pyruvate, producing a small amount of ATP and NADH. Stage 2 When oxygen is present, pyruvate and NADH are used to make a large amount of ATP. When oxygen is not present, pyruvate is converted to either lactate or ethanol and carbon dioxide.

43 Section 3 Cellular Respiration Cellular Respiration

44 Section 3 Cellular Respiration Cellular Respiration

45 Section 3 Cellular Respiration Stage One: Breakdown of Glucose Glycolysis In the first stage of cellular respiration, glucose is broken down in the cytoplasm during a process called glycolysis. As glucose is broken down, some of its hydrogen atoms are transferred to an electron acceptor called NAD +. This forms an electron carrier called NADH.

46 Section 3 Cellular Respiration NAD + and NADH

47 Section 3 Cellular Respiration Stage One: Breakdown of Glucose, continued Glycolysis Glycolysis occurs in four steps: Step 1 Phosphate groups from two ATP molecules are transferred to a glucose molecule. Step 2 The resulting six-carbon compound is broken down to two three-carbon compounds. Step 3 Two NADH molecules are produced, and each compound gains one more phosphate group. Step 4 Each three-carbon compound is converted to a threecarbon pyruvate, producing four ATP molecules in the process.

48 Section 3 Cellular Respiration Glycolysis

49 Section 3 Cellular Respiration Glycolysis

50 Section 3 Cellular Respiration Stage Two: Production of ATP When oxygen is present, pyruvate produced during glycolysis enters a mitochondrion and is converted to a two-carbon compound. This reaction produces one carbon dioxide molecule, one NADH molecule, and one two-carbon acetyl group. The acetyl group is attached to a molecule called coenzyme A (CoA), forming a compound called acetyl-coa.

51 Section 3 Cellular Respiration Stage Two: Production of ATP, continued Krebs Cycle Acetyl-CoA enters a series of enzyme-assisted reactions called the Krebs cycle, which follows five steps: Step 1 Acetyl-CoA combines with a four-carbon compound, forming a six-carbon compound and releasing coenzyme A. Step 2 Carbon dioxide is released from the six-carbon compound, forming a five-carbon compound. Electrons are transferred to NAD +, making a molecule of NADH.

52 Section 3 Cellular Respiration Stage Two: Production of ATP, continued Krebs Cycle Step 3 Carbon dioxide is released from the compound. A molecule of ATP and a molecule of NADH are made. Step 4 The existing four-carbon compound is converted to a new four-carbon compound. Electrons are transferred to an electron acceptor called FAD, making a molecule of FADH 2, another type of electron carrier. Step 5 The new four-carbon compound is then converted to the four-carbon compound that began the cycle. Another molecule of NADH is produced.

53 Section 3 Cellular Respiration Krebs Cycle

54 Section 3 Cellular Respiration Krebs Cycle

55 Section 3 Cellular Respiration FAD and FADH 2

56 Section 3 Cellular Respiration Stage Two: Production of ATP, continued Electron Transport Train In aerobic respiration, electrons donated by NADH and FADH 2 pass through an electron transport chain. In eukaryotic cells, the electron transport chain is located in the inner membranes of mitochondria. At the end of the electron transport chain, hydrogen ions and spent electrons combine with oxygen molecules forming water molecules.

57 Section 3 Cellular Respiration Electron Transport Chain of Aerobic Respiration

58 Section 3 Cellular Respiration Respiration in the Absence of Oxygen When oxygen is not present, NAD + is recycled in another way. Under anaerobic conditions, electrons carried by NADH are transferred to pyruvate produced during glycolysis. This process recycles NAD + needed to continue making ATP through glycolysis. The recycling of NAD + using an organic hydrogen acceptor is called fermentation.

59 Section 3 Cellular Respiration Fermentation

60 Section 3 Cellular Respiration Respiration in the Absence of Oxygen, continued Lactic Acid Fermentation In some organisms, a three-carbon pyruvate is converted to a three-carbon lactate through lactic acid fermentation. Fermentation enables glycolysis to continue producing ATP in muscles as long as the glucose supply lasts.

61 Section 3 Cellular Respiration Respiration in the Absence of Oxygen, continued Alcoholic Fermentation In some organisms, the three-carbon pyruvate is broken down to ethanol (ethyl alcohol), a two-carbon compound, through alcoholic fermentation. As in lactic acid fermentation, NAD + is recycled, and glycolysis can continue to produce ATP.

62 Section 3 Cellular Respiration Respiration in the Absence of Oxygen, continued Lactic Acid and Alcoholic Fermentation When oxygen is not present, cells recycle NAD + through fermentation.

63 Section 3 Cellular Respiration Respiration in the Absence of Oxygen, continued Production of ATP When oxygen is present, aerobic respiration occurs to produce ATP. When oxygen is not present, fermentation occurs instead.

64 Section 3 Cellular Respiration Cellular Respiration Versus Fermentation

65 Section 3 Cellular Respiration Comparing Aerobic and Anaerobic Respiration

66 Standardized Test Prep Multiple Choice The chart below shows data on photosynthesis in one type of plant. Use the chart to answer questions 1 3.

67 Standardized Test Prep Multiple Choice, continued 1. Which statement is supported by the data? A. Photosynthesis does not occur at 0 C. B. The optimum temperature for photosynthesis is approximately 46 C. C. The rate of photosynthesis at 40 C is greater than the rate at 20 C. D. The rate of photosynthesis increases as temperature increases from 25 C to 30 C.

68 Standardized Test Prep Multiple Choice, continued 1. Which statement is supported by the data? A. Photosynthesis does not occur at 0 C. B. The optimum temperature for photosynthesis is approximately 46 C. C. The rate of photosynthesis at 40 C is greater than the rate at 20 C. D. The rate of photosynthesis increases as temperature increases from 25 C to 30 C.

69 Standardized Test Prep Multiple Choice, continued 2. At approximately what temperature is the plant producing oxygen at the greatest rate? F. 0 C G. 23 C H. 46 C J. 50 C

70 Standardized Test Prep Multiple Choice, continued 2. At approximately what temperature is the plant producing oxygen at the greatest rate? F. 0 C G. 23 C H. 46 C J. 50 C

71 Standardized Test Prep Multiple Choice, continued 3. Data obtained from a different type of plant show a similar relationship between rate of photosynthesis and temperature, but the curve is shifted to the right. What environment would this plant be best adapted to? A. Cold subarctic environment B. Cool, wet environment C. Mild, dry environment D. Hot equatorial environment

72 Standardized Test Prep Multiple Choice, continued 3. Data obtained from a different type of plant show a similar relationship between rate of photosynthesis and temperature, but the curve is shifted to the right. What environment would this plant be best adapted to? A. Cold subarctic environment B. Cool, wet environment C. Mild, dry environment D. Hot equatorial environment