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

H2O + 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 + oxygenLight + 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 CO2

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

H20 + ADP +Pi + NADP+

02 + 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

CO2 + ATP + NADPH

C6H12O6 + ADP+Pi + NADP+

Photosynthesis

solar energy + CO2 + H2O C6H1206 + O2

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 + O2 H2O + CO2 + 34

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 O2

some O2

FORMULA:

pyruvate + NADH

lactic 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+ + 2 ethanol + 2CO2

process is used to make alcoholic beverages

LACTIC ACID ALCOHOL FERMENTATION FERMENTATION

COMPARISON ANAEROBIC

Glycolysis 2 ATP Glycolysis 2 ATP

Product: lactic acid Product: ethanol + CO2Potential: 34 more ATP Potential: no more ATP

AEROBIC RESPIRATION ANAEROBIC RESPIRATION

OVERALL COMPARISON

Glycolysis 2 ATP Glycolysis 2 ATP

Step 2: 34 ATP Step 2: 0 ATP36 ATP 2 ATP