BIOENERGETIC REACTIONS

Photosynthesis

Overview All energy on earth comes from the sun. Humankind depends on: Plants Algae Cyanobacteria (photosynthetic bacteria) to provide this energy for us!

Carbon dioxide and water are taken in by plants Plants absorb light energy from the sun and convert it to a usable form (ATP) Energy is used to produce sugar molecules which are a useful form of chemical energy Sugar is converted to starch and stored for use by the plant.

Chloroplasts Have TWO membranes The inner membrane is called the thylakoid. The thylakoid is folded and looks like stacks of coins called granum. The stroma is the space surrounding the granum

Chloroplasts Chlorophyll molecules are embedded in the thylakoid membrane Act like a light “antenna” These molecules can absorb the sun’s energy.

Light Dependent Reactions Happen ONLY in sunlight. Light is absorbed by chlorophyll molecules. The energy generates molecules of ATP

Light Independent Reactions Happen in sunlight, and in the dark. ATP generated by the LDR drives the Calvin Cycle. Glucose is a product. Glucose can be used to “build” starches.

Overall Reaction What is the equation for photosynthesis? carbon dioxide + water  glucose + oxygen + energy 6CO2 + 6H2O  C6H12O6 + 6O2 + energy

Summary

THE REACTIONS Photosynthesis uses light-dependent and light independent reactions (i.e. the Calvin cycle) L.D.R occur in the thylakoid and produce ATP and oxygen. The L.I.R. (Calvin cycle) uses ATP and NADPH to produce high energy sugars.

BIOENERGETIC REACTIONS

  Cellular Respiration

Both photosynthesis and cellular respiration provide energy for life. Both photosynthesis and cellular respiration provide energy for life. Photosynthesis uses solar energy to produce glucose and oxygen from carbon dioxide and water 6CO2 + 6H20 + Energy C6H12O6 + 6O2 Occurs in chloroplasts

Cellular respiration produces ATP and consumes oxygen during the production of glucose to form carbon dioxide and water C6H12O6 + 6O2 6CO2 + 6H2O + ATP Occurs in mitochondria

+ Sunlight energy ECOSYSTEM Photosynthesis in chloroplasts Glucose CO2 ATP ECOSYSTEM Sunlight energy Photosynthesis in chloroplasts Cellular respiration in mitochondria (for cellular work) Heat energy +

What is the relationship between respiration and cellular respiration? CO2 O2 Bloodstream Muscle cells carrying out Cellular Respiration Breathing Glucose + O2 CO2 +H2O +ATP Lungs

Both plant and animal cells carry out the final stages of cellular respiration in their mitochondria.

Glucose is the main energy source used by all cells. Cells don’t “burn” glucose. Instead, they gradually release the energy from glucose and other food compounds. This process begins with a pathway called glycolysis.

Stage 1 – Glycolysis Occurs in the cytoplasm An anaerobic process   Stage 1 – Glycolysis Occurs in the cytoplasm An anaerobic process Breaks down glucose into pyruvic acid Produces a net gain of 2 ATP molecules

Stage 2– Krebs Cycle An aerobic process – oxygen IS required Occurs in the mitochondria An aerobic process – oxygen IS required Produces 2 ATP Begins with pyruvic acid

Stage 3 – Electron Transport Chain (ETC)   Uses electron carriers to make ATP Electrons from NADH and FADH2 travel down the concentration gradient, which picks up H+ to form H2O. Produces 32 ATP

(per glucose molecule ) PRODUCTION TOTALS (per glucose molecule ) 2 ATP – Glycolysis 2 ATP – Kreb’s cycle 32 ATP – Electron Transport Chain 36 ATP Total for cellular respiration

Fermentation is an anaerobic alternative to cellular respiration Under anaerobic conditions, many kinds of cells can use glycolysis alone to produce small amounts of ATP 2 types – Lactic Acid Fermentation Alcohol Fermentation

Anaerobic Anaerobic Aerobic