Energy Flashcards
Stored energy
Potential energy
Energy of motion
Kinetic energy
The flow begins with
Production of high-energy, reduced compounds by photosynthesis
How organisms can be divided depending on their source of energy
Phototrophs and chemotrophs
How phototrophs get energy
Transform sunlight energy into chemical
Photoautotrophs
solar energy to produce all the carbon compounds they need from CO2 (photosynthesis)
- include plants, algae, cyanobacteria, and photosynthetic bacteria
Photoheterotrophs
Rely on intake of organic molecules as a source of carbon
Purple nonsulfur bacteria
How chemotrophs get energy?
By oxidizing chemical bonds in molecules
Chemoautotrophs
Energy: oxidize inorganic compounds (H2S, H2) or inorganic ions
Carbon source: CO2
Extremophiles, archae
Chemoheterotrophs
Energy and carbon use: ingest and use chemical compounds (carbohydrates, fats, proteins)
All animals, Protozoa, fungi, many bacteria
C6H12O6 + 6O2 → CO2 + 6H2O + energy
Glucose oxidation
CH4 + 2O2 → CO2 + 2H2O + energy
Methane oxidation
Energy + 6CO2 + 6H2O → C6H12O6 + 6O2
Carbon dioxide reduction
Three constant variables in biol reactions
Same temperature, pressure, volume
1st law thermodynamics
Energy cannot be created or destroyed (changes form)
What is the enthalpy H?
Measure of total energy of a thermodynamic system
Positive change in H
Heat absorbing endothermic reactions
Negative change in enthalpy H?
Heat-releasing exothermic reactions
The second law of thermodynamics
The total entropy of a system plus of its surroundings always increases
entropy
measure of the disorder or randomness of a system
e.g. when ice melts
free energy (G)
measure of spontaneity for a system
change in free energy<0
reaction will proceed as written - exergonic
change in free energy>0
reaction will proceed in reverse - endergonic
Where the energy is stored in ATP?
in the bonds between phosphate groups
4 essential needs of the cell
molecular building blocks for biosynthesis
chemical catalysts called enzymes
information to guide all its activities
energy to drive the various reactions and processes