Cell Reactions and Energy ATP: energy molecule of the cell bond holding the 3rd phosphate is a high energy bond and can be easily broken H 2 O + ATP --> ADP + Pi + Energy

Endergonic Reactions (energy IN), anabolic reaction (making molecules) Cell Reactions and Energy Exergonic Reactions (energy OUT), catabolic reactions (breaking molecules apart)

An anabolic process Photosynthesis autotrophs produce their own food by photosynthesis; the process occurs in the chloroplast

Photosynthesis glucose + oxygen Light + chlorophyll overall reaction: carbon dioxide + water

Photosynthesis photosynthesis occurs in two steps: 1. Light Dependent Reactions: Making high energy products 2.Light Independent Reactions (carbon fixation): Using the high energy products to capture CO 2

 only take place in the presence of light 1. Light dependent reaction  solar energy is absorbed by chlorophyll in chloroplasts  water molecules are split (oxygen is released into atmosphere, hydrogen takes part in light independent reactions)  occurs in the thylakoid disk membrane

FORMULA: 1. Light dependent reaction H ADP +Pi + NADP+  ATP + NADPH [high energy products]

hydrogen and carbon dioxide combine to form glucose molecules 2. Light independent reaction occurs in the stroma plants use some glucose for life processes (e.g. growth, reproduction) most plants convert glucose to starch (for storage)

FORMULA: 2. Light independent reaction CO 2 + ATP + NADPH C 6 H 12 O 6 + ADP+Pi + NADP +

Photosynthesis solar energy + CO 2 + H 2 O C 6 H O 2 overall reaction:

Cell Respiration cell respiration is the release of energy from food (glucose) all cells perform this catabolic process cell respiration occurs in two steps: Step 1: Glycolysis Step 2: Aerobic or Anaerobic respiration

 occurs in the cytoplasm 1. Glycolysis FORMULA: glucose + 2 ADP + 2 Pi + 2 NAD +  2 pyruvate + 2 ATP + 2 NADH

 this process does not produce very much energy 1. Glycolysis  most of the energy is still contained in the bonds of the 2 pyruvates  there are three possible reactions that break down pyruvate (step 2)

Step 2: getting rid of pyruvate Cell Respiration  cells must replace NAD + as it is needed in glycolysis and if the cell runs out, glycolysis stops There are two options: AEROBIC CELLULAR RESPIRATION ANAEROBIC CELLULAR RESPIRATION

 occurs in the mitochondria  the process is aerobic (oxygen dependent)  2 pyruvate + O 2  H 2 O + CO ATP 2a. Aerobic Cellular Respiration

2b. Anaerobic cellular respiration Lactic Acid Fermentation:  occurs only in animal muscle cells that are deprived of oxygen  if oxygen is unavailable for aerobic respiration, the cell converts the pyruvate into lactic acid which causes muscle cramps  when oxygen is available, the lactic acid is converted back into pyruvate

2b. Anaerobic cellular respiration Lactic Acid Fermentation: no O 2 some O 2 FORMULA: pyruvate + NADHlactic acid + NAD +

2b. Anaerobic cellular respiration Alcohol Fermentation:  occurs in anaerobic yeast and bacteria, as they do not have mitochondria Formula: 2 pyruvate + 2 NADH  2 NAD ethanol + 2CO 2 process is used to make alcoholic beverages

LACTIC ACID ALCOHOL FERMENTATION FERMENTATION COMPARISON ANAEROBIC Glycolysis2 ATP Product: lactic acid Product:ethanol + CO 2 Potential:34 more ATP Potential:no more ATP

AEROBIC RESPIRATION ANAEROBIC RESPIRATION OVERALL COMPARISON Glycolysis 2 ATP Glycolysis2 ATP Step 2:34 ATP Step 2:0 ATP 36 ATP2 ATP