Chapter 4: Energy and Cellular Metabolism Flashcards
characteristics of complex things that are unexpected based on the basic components
emergent properties
what are the properties of living organisms?
- complex structure whose basic unit is a cell
- aquire, transform, store, and use energy
- sense and respond to internal & external environements
- maintain homeostasis
- store, use and transmit info
- reproduce, develop, grow, and die
- have emergent properties
- individuals adapt and species evolve
where can organisms get energy?
- sunlight for plants (photosynthesis)
- chemical bonds for animals (respiration)
- open system
what does photosynthesis yield?
energy store in biomolecules
what does respiration yield?
- energy for work
- energy stored in biomolecules
- H2O and CO2
broadly defined as the capacity to perform work
energy
what are the various forms of energy or “work”
chemical work
transport work
mechanical work
Making and breaking of chemical bonds
chemical work
- Moving ions, molecules, and larger particles
* Creating concentration gradients
transport work
- Moving organelles, changing cell shape, beating flagella and cilia
- Contracting muscles
mechanical work
what are the two forms of energy?
- kinetic energy
* potential energy
- energy of motion
- work involves movement
- thermal energy, electromagnetic energy, electrical energy
kinetic energy
- stored energy
- concentration gradients & chemical bonds
potential energy
- Total amount of energy in the universe is constant (closed system)
- Energy can be neither created nor destroyed
first law of thermodynamics
Processes move from a state of order to randomness or disorder (entropy)
second law of thermodynamics
always accompanied by either the release of energy or the input of energy
chemical reactions
the study of energy flow through biological systems
bioenergetics
the potential energy stored in the chemical bonds that is available to do work
free energy
the initial energy required to bring the reactants into a position to react with each other
activation energy
the difference in free energy between reactants and products.
Net free energy change of a reaction
- releases energy because the products have less energy than the reactants
- spontaneous
exergonic
*requires an input of energy
*trap some activation energy in the
products, which then have more free energy than the reactants
*nonspontaneous
endergonic
where does the activation energy come from?
Coupling an exergonic reaction to an endergonic reaction
biomolecules (mostly proteins) specialized to act as catalysts
enzymes
substances that increase the rates of chemical reactions
catalysts
how do enzymes speed up reactions?
by lowering the activation energy?
called substrates
reactants
- vitamin-derived cofactors that do not have catalytic activity but participate directly in the reactions catalyzed by enzymes
- carry chemical groups from one reaction to another
coenzymes
what are examples of coenzymes?
FAD
NAD
coenzyme A
how can enzyme activity be modulated?
- chemical factors (allosteric regulation)
* changes in temperature and pH
what are the categories of enzymatic reactions?
- oxidation-reduction
- hydrolysis-dehydration
- addition-subtraction-exchange
- ligation
transfer electrons from one molecule to another
oxidation-reduction
combined or separate two molecules losing or gaining water in the process.
hydrolysis-dehydration
either adds, subtracts, or exchanges functional groups
Addition-subtraction-exchange reactions