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Learn about how organisms utilize energy, the role of photosynthesis in plants, and cellular respiration in breaking down glucose to produce ATP. Explore the key components, reactions, and stages involved in these essential processes.
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Photosynthesis & Cellular Respiration Ch. 8 & 9
Food and Energy Heterotrophs – Eat food Autotrophs - Photosynthesis
Organisms & their Sources of Energy -Autotrophs: organisms that make their own food Ex. Plants, algae, some bacteria -Heterotrophs: feed on other organisms Ex. Animals, fungi, some bacteria, some protists
Chapter Overview: Food & Energy Plants Photosynthesis (chloroplast) Cell Respiration (mitochondria) Food ATP Consume food (digestive sys) Animals
ATP • Energy Molecule – ATP – adenosine triphosphate • Cells store energy by adding a phosphate group to ADP • Cells release energy from ATP by subtracting a phosphate group High energy bond ATP= high energy molecule; ADP= low energy molecule
The Big Picture! CO2 ATP!! O2 We get our energy from the food (glucose) plants made during photosynthesis when we eat plants or eat animals that ate the plants by cellular respiration. Green plants trap energy from sunlight in their leaves and make food (glucose)
6CO2 + 6H2OC6H12O6 + 6O2 reactants products Photosynthesis Equation
Photosynthesis occurs in the Chloroplast Parts of the Chloroplast: -thylakoid: flattened sacs that contain pigments (chlorophyll) -stroma: protein rich fluid surrounding thylakoid -grana: stack of thylakoids
Photosynthesis Pigments absorb light and convert it to chemical energy (glucose) Types of pigments: Chlorophyll a (dark green); chlorophyll b (light green); carotenoids (yellow/orange/red)
Pigment - Chlorophyll Responsible for absorbing and reflecting sunlight
Why do leaves change color in the fall? • Leaves contain many light absorbing/reflecting pigments • During autumn, when less light is available, chlorophyll does not reflect as much, allowing other pigments, which reflect different colors to show through
Photosynthesis Overview 6CO2 + 6H2O C6H12O6 + 6O2 LIGHT ENERGY Carbon Dioxide Water Glucose Oxygen Light Energy Chloroplast CO2 + H2O Sugars + O2
Photosynthesis -“The Reaction” 6CO2 + 6H2O --> C6H12O6 + 6 O2 2 Stages of Photosynthesis 1. Light Dependent Rxn 2. Light Independent Rxn (Calvin cycle)
Light Dependent Reactions 1.light energy absorbed (by thylakoids) 2.H2O split, breaking into three pieces H2O--> O2 + H+ + e- 3. O2 exits the leaves (becomes our breathing O2) 4. H+ and e- carried onto step 2 by NADP+ and ADP
Side Note: High Energy Electron • Light energy produces high energy electrons in chlorophyll, which are used in photosynthesis. • Electron Carrier: accept high-energy electrons and transfer them to another molecule. -2 Types: *FAD is used in cell respiration – we’ll talk about this later!
Light Dependent Reactions H2O Sun (light energy) NADP+ ADP & P LDR thylakoid e- H+ ATP NADPH O2
Light Independent (Calvin Cycle) - Takes place in the stroma 1. CO2 enters thru stomata 2. H+ (from light dependent rxn) is combined with CO2 to produce Glucose = C6H12O6 - ATP is a little burst of energy to make the Calvin cycle start *Can take place in light or dark
Stomata CO2 enters leaf through Stomata H2O and O2 leave through Stomata
CO2 NADP+ ADP & P Calvin Cycle stroma e- H+ ATP NADPH Glucose!!C6H12O6
Glucose C6H12O6 • Where does each atom come from? • 6 C comes from CO2 • 12 H comes from H2O • 6 O comes from CO2
Follow the colored atoms! CO2 H2O Sun (light energy) NADP+ ADP & P Calvin Cycle (stroma) LDR (granum) e- H+ ATP NADPH C6H12O6Glucose!! O2
Factors affecting Photosynthesis • Temperature • Optimal temps 0 – 35°C • Remember, enzymes work at specific temps! • Light • Too much light will not have an extra effect on photosynthesis • Water • Waxy cuticle prevents water loss
Extreme Photosynthesis • C4 Plants • Corn and sugar cane • Hot temps & intense light • Normal amounts of water • Efficient CO2 is obtained even when stomata are closed • CAM Plants • Hot temps & intense light • Dry (less water) • Cactus • Open stomata at night only!
Cellular Respiration -Glucose is broken down to produce ATP (energy) -Done by ALL living things (plants and animals) Location: occurs in mitochondria Equation: C6H12O6 + 6 O2 6CO2 + 6H2O + ATP (the reverse of photosynthesis)
2 Types of Cellular Respiration 1. Aerobic Respiration: O2 required -produces net total of 38 ATP per glucose 2. Anaerobic Respiration: occurs when there is no O2 -produces 2 ATP per glucose
2 POSSIBLE PATHWAYS 1. Glycolysis O2 present No O2 present 2. Citric Acid Cycle (Krebs) Aerobic = O2 2. Alcoholic Fermentation Anaerobic = No O2 OR 3. Electron Transport Chain 2. Lactic Acid Fermentation
3 Stages of Aerobic Cell Resp • Glycolysis • Breaks glucose • Releases 2 ATP • Citric Acid Cycle (Krebs Cycle) • Releases 2 ATP • Electron Transport Chain • Releases 34 ATP
1. Glycolysis Electrons carried in NADH Pyruvic acid Glucose Glycolysis Cytoplasm 2
2. Citric Acid Cycle / Krebs Cycle Electrons carried in NADH Pyruvic acid Electrons carried in NADH and FADH2 Krebs Cycle (matrix) Glucose Glycolysis Mitochondrion Cytoplasm 2 2
3. Electron Transport Chain Electrons carried in NADH Pyruvic acid Electrons carried in NADH and FADH2 Krebs Cycle (matrix) Electron Transport Chain (cristae) Glucose Glycolysis (Cytoplasm) Mitochondrion 2 2 34
Anaerobic Cell Respiration • If no oxygen is present…Fermentation aka Anaerobic Cell Resp occurs • 2 types: • Alcoholic Fermentation • Lactic Acid Fermentation • ONLY 2 ATP MADE TOTAL! ** Not efficient! **
Alcohol Fermentation -done by bacteria and yeast, NOT animals • Glycolysis • Product changed into ethanol (alcohol) + CO2 Example: Yeast in bread; alcohol in wine/beer
Lactic Acid Fermentation -done by animal cells (humans) 1. Glycolysis 2. Product changed into lactic acid + CO2 Example: Muscle cramps/fatigue & bacteria incheese/yogurt
Relationship between plants and animals • Without plants, animals could not survive and vice versa! • Biochemical Pathway – a set of reactions in which the products of one reaction is used as a reactant in the next reaction. Glucose + O2