Section 5-1

•Directly/indirectly, almost all energy in LTs needed for metabolism comes from the sun.

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

Section 5-1Heterotrophs:•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

All animals

Most fungi

Most bacteria

Mos

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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

ATPATP

Section 5-1ATP (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

Section 5-2Stages 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

Section 5-2

Stage 1: Capture Light Energy/O2 releasedPigments: •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

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Section 5-2Carotenoids:•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

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Section 5-2Stage 1: Capture Light Energy/O2 releasedThylakoids:•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

Section 5-2Stage 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

Section 5-2

Stage 3: Store Energy in Organic CompoundsCarbon dioxide fixation: •C atoms from atmospheric CO2 are used to store chemical energy in organic compoundsCalvin cycle: •series of enzyme-assisted rxn produces organic compounds

Section 5-2Factors that Affect Photosynthesis:•Photosynthesis ↑ as light intensity ↑ until all pigments are being used

•Photosynthesis is most efficient w/in certain temperature range

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

Section 5-32 Stages of Cellular Respiration:Stage 1: •Glucose converted to pyruvate, makes small amt of ATP/NADHStage 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

Section 5-3

Stage 1: Breakdown of Glucose/GlycolysisGlycolysis: •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

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

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

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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 madevia ETC

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