Photosynthesis and Cellular Respiration

Two ways to get food “troph” = food Autotrophs Heterotrophs Auto = self Autotrophs make their own food Heterotrophs Hetero = different Heterotrophs get their food from something else (they have to eat it)

Two ways to get food Autotrophs Plants Heterotrophs Animals

Photosynthesis

Photosynthesis Converts the sun’s energy into chemical energy stored in sugar Takes place in specialized structures inside plant cells called chloroplasts Chlorophyll is the pigment that absorbs sunlight.

Photosynthesis Reaction 6CO2 + 6 H2O + light energy → C6H12O6 + 6O2 The food plants make is called glucose (sugar)

Photosynthesis 2 different reactions Light Reactions Calvin Cycle Capture light energy for photosynthesis Calvin Cycle Produces glucose sugar

Cellular Respiration Cells Breathing

Cellular Respiration Happens in both plant and animal cells Overall Reaction: C6H12O6 + 6O2 → 6CO2 + 6H2O

Cellular Respiration Overview Depends on whether or not there is oxygen Aero = oxygen Aerobic Respiration – makes energy Anaerobic Respiration – Fermentation (makes alcohol)

Step 1: Glycolysis The energy that cells make and use is called ATP Adenosine triphosphate Glycolysis makes 2 molecules of ATP (energy) Glycolysis happens in the cytoplasm of the cell

Step 2: Check for Oxygen If oxygen is present, the cell can make more ATP If no oxygen is present, the cell has to recycle the pieces from glycolysis and makes alcohol.

Step 3 with oxygen: Cellular Respiration Oxygen required=aerobic 2 more sets of reactions which occur the cell’s mitochondria 1. Kreb’s Cycle – makes 2 ATP Also called the Citric Acid Cycle 2. Electron Transport Chain – makes 32-34 ATP

Kreb’s Cycle (Citric Acid Cycle)

Step 3 without oxygen: Fermentation The cell must recycle the materials from glycolysis. This recycling process is called fermentation. The product of fermentation is alcohol.

Energy Tally 36 ATP for aerobic vs. 2 ATP for anaerobic Glycolysis 2 ATP Kreb’s 2 ATP Electron Transport 32 ATP 36 ATP Anaerobic organisms can’t be too energetic but are important for global recycling of carbon