Chapter 5 Photosynthesis and Cellular Respiration

Section 5-1 Directly/indirectly, almost all energy in LTs needed for metabolism comes from the sun.

Building Molecules that Store Energy: Section 5-1 Building Molecules that Store Energy: Photosynthesis: process by which light energy is converted to chemical energy. Autotrophs: Organisms that use energy from sunlight or from chemical bonds in inorganic substances to make organic compounds; plants, bacteria

Cellular respiration: Section 5-1 Heterotrophs: Organisms that must get energy from food instead of from sunlight/inorganic substances Cellular respiration: Metabolic process in which consumed food energy is converted to ATP energy Most fungi Most bacteria Most protozoa All animals

Transfer of Energy to ATP: Section 5-1 Transfer of Energy to ATP: When cells break down food molecules, some energy is released as heat. Most remaining energy is stored in ATP Like money, ATP is a portable form of energy “currency” in cells and is delivered wherever it is needed in the cell ATP ATP

ATP (adenosine triphosphate): Section 5-1 ATP (adenosine triphosphate): nucleotide w/ 2 extra energy-storing phosphate groups Energy is released when bonds holding phosphate groups together are broken Removal of phosphate group from ATP produces adenosine diphosphate, ADP

Stages of Photosynthesis: Stage 1 Energy captured from sunlight Section 5-2 Stages of Photosynthesis: Stage 1 Energy captured from sunlight Stage 2 Light energy converted to ATP and energy carrier NADPH Stage 3 Using CO2 and energy stored in ATP and NADPH powers the formation of organic compounds 6CO2 +6H2O C6H12O6 +6O2

Stage 1: Capture Light Energy/O2 released Pigments: Section 5-2 Stage 1: Capture Light Energy/O2 released Pigments: Contain light-absorbing substances Chlorophyll: Main pigment involved in photosynthesis, absorbs mostly blue/red light, reflects green/yellow light Plants contain 2 types of chlorophyll, chlorophyll a and b more…

Section 5-2 Carotenoids: Pigments that produce yellow/orange fall leaf colors, fruits, vegetables, flowers Carotenoids absorb different wavelengths from chlorophyll, so having both pigments enables plants to absorb more light energy during photosynthesis more…

Stage 1: Capture Light Energy/O2 released Thylakoids: Section 5-2 Stage 1: Capture Light Energy/O2 released Thylakoids: Clusters of pigments embedded in mem of disk-shaped structures Light strikes thylakoid, energy is transferred to e- in chlorophyll Causes e- to jump to higher energy level e- are replaced by splitting water and O2 is released

Stage 2: Convert Light Energy to ATP/NADPH Section 5-2 Stage 2: Convert Light Energy to ATP/NADPH Excited e- leave chlorophyll to make ATP/NADPH that temporarily store energy 1st excited e- jumps to nearby molecule in thylakoid membrane; e- is passed through series of molecules along thylakoid membrane, electron transport chain (ETC) and ATP/NADPH are made

Stage 3: Store Energy in Organic Compounds Carbon dioxide fixation: Section 5-2 Stage 3: Store Energy in Organic Compounds Carbon dioxide fixation: C atoms from atmospheric CO2 are used to store chemical energy in organic compounds Calvin cycle: series of enzyme-assisted rxn produces organic compounds

Factors that Affect Photosynthesis: Section 5-2 Factors that Affect Photosynthesis: Photosynthesis ↑ as light intensity ↑ until all pigments are being used Photosynthesis is most efficient w/in certain temperature range

Metabolic processes that need O2 Anaerobic: Section 5-3 O2 makes production of ATP more efficient, although some ATP is made w/o O2 Aerobic: Metabolic processes that need O2 Anaerobic: Metabolic processes that don’t need O2

2 Stages of Cellular Respiration: Stage 1: Section 5-3 2 Stages of Cellular Respiration: Stage 1: Glucose converted to pyruvate, makes small amt of ATP/NADH Stage 2: O2 present, pyruvate/NADH used to make large amt of ATP via ETC O2 not present, pyruvate converted to either lactate or ethanol/CO2

Stage 1: Breakdown of Glucose/Glycolysis Glycolysis: Section 5-3 Stage 1: Breakdown of Glucose/Glycolysis Glycolysis: 1st stage of cellular respiration, glucose is broken down in cytoplasm As glucose is broken down, some of its H atoms are transferred to an e- acceptor called NAD+ to form an e- carrier NADH Some ATP, NADH, 2 pyruvates result

Stage 2: Production of ATP Section 5-3 Stage 2: Production of ATP O2 is present, pyruvate enters mitochondria and is converted to 2-C compd This rxn produces 1 CO2 molecule, 1 NADH molecule, and 1, 2-C acetyl group Acetyl group is attached to coenzyme A (CoA), forming acetyl-CoA that enters the Krebs Cycle more…

Stage 2: Production of ATP via Krebs Cycle Section 5-3 Stage 2: Production of ATP via Krebs Cycle Krebs cycle: series of rxns in the mitochondria where 6 NADH, 2 FADH2, and 2 ATP are made more…

Stage 2: Production of ATP via ETC Section 5-3 Stage 2: Production of ATP via ETC In aerobic respiration, e- donated by NADH and FADH2 pass through ETC In eukaryotic cells, ETC is located in inner membranes of mitochondria At end of ETC, H+ ions and e- combine w/ O molecules forming H2O 34 ATP made via ETC

Respiration w/o Oxygen is Fermentation Section 5-3 Respiration w/o Oxygen is Fermentation When O2 is present, aerobic respiration occurs to produce ATP When O2 isn’t present, fermentation occurs producing lactic acid in animals or in plants alcohol/CO2