Chapter 5 Photosynthesis and Cellular Respiration - PowerPoint PPT Presentation

Chapter 5 Photosynthesis and Cellular Respiration

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 5-1

• 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

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

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

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

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, chlorophylla 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…

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

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

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

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

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 5-3

• 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

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

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…

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…

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
• 34ATP made
• via ETC

Section 5-3

• Respiration w/o Oxygen is Fermentation
• When O2is present, aerobic respiration occurs to produce ATP
• When O2isn’t present, fermentation occurs producing lactic acid in animals or in plants alcohol/CO2