Chapter 8 - An Introduction to Metabolism Flashcards

Bioluminescence: When organisms convert energy into light.
Metabolism
- The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism.
- An emergent property of life that arises from interactions between molecules within the cell
Metabolic Pathway
- A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule to simpler molecules (catabolic pathway)
- Begins with a specific molecule and ends with a product
- Each step is catalyzed by a specific enzyme
- Structures within the cell help bring order to metabolic pathways

Catabolic Pathways
- A metabolic pathway that releases energy by breaking down complex molecules to simpler molecules
- Cellular respiration, the breakdown of glucose in the presence of oxygen, is an example of a pathway or catabolism
Anabolic Pathways
- A metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules
- The synthesis of protein from amino acids is an example of anabolism
Bioenergetics
- The study of how energy flows through organisms
- The overall flow and transformation of energy in an organism
Energy
- The capacity to cause change, especially to do work (to move matter against an opposing force)
- Energy can be converted from one form to another
- Forms of energy
- Kinetic energy
- Potential Energy

Kinetic Energy
- The energy associated with the relative motion of objects
- Moving matter can perform work by imparting motion to other matter

Potential Energy
- The energy that matter possesses as a result of its location or spatial arrangement (structure)

Chemical Energy
- Energy available in molecules for release in a chemical reaction
- A form of potential energy
Heat (Thermal Energy)
- The total amount of kinetic energy due to the random motion of atoms or molecules in a body of matter
- Heat is energy in its most random form
Thermodynamics
- The study of energy transformations that occur in a collection of matter
- Has 2 laws
- Energy flows into an ecosystem in the form of light and exits in the form of heat
Isolated System
- An energy system isolated from its surroundings
- Example is the liquid in a thermos
- Reactions in a closed system eventually reach equilibrium and then do no work
Open System
- An energy system where energy and matter can be transferred between the system and its surroundings
- Organisms are open systems
- Energy flows into an ecosystem in the form of light and exits in the form of heat
- Not in equilibrium; they are open systems experiencing a constant flow of materials
The First Law of Thermodynamics
- The principle of concervation of energy: Energy can be transferred and transformed, but it cannot be created or destroyed
- The energy of the universe is constant

The Second Law of Thermodynamics
- The principle stating that every energy transfer or transformation increases the entropy of the universe.
- During every energy transfer or transformation, some energy is often lost as heat
- Living cells unavoidably convert organized forms of energy to heat

Entropy
A measure of disorder, or randomness
Spontaneous Process
- A process that occurs without an overall input of energy
- For a process to occur without energy input, it must increase the entropy of the universe
- A process that is energetically favorable
- Can happen quickly or slowly
Biological Order and Disorder
- Cells create ordered structures from less ordered materials
- Simpler molecules are ordered into the more complex structure of an amino acid, and amino acids are ordered into polypeptide chains.
- At the organismal level, complex and ordered structures result from biological processes that use simpler starting materials. (As in the picture)
- Organisms also replace ordered froms of metter and energy with less ordered forms
- An animal obtains starch, proteins, and other complex molecules from the food it eats. As catabolic pathways break these molecules down, the animal releases carbon dioxide and water (smaller molecules that possess less chemical energy than the food did.
- Energy flows into ecosystems in the form of light and exits in the form of heat.

How does the evolution of more complex organisms not violate the second law of thermodynamics?
Entropy may decrease in an organism, but the universe’s total entropy increases.
Free Energy (ΔG or δG)
- The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system.
- A measure of a system’s instability, its tendency to change to a more stable state
- Equilibrium is a state of maximum stability
- Spontaneous processes can be harnessed to perform work
- Only Processes with a negative ΔG are spontaneous
- During a spontaneous change, free energy decreases and the stability of a system increases
- A process is spontaneous andn can perform work only when it is moving toward equilibrium
- The change in free energy of a system (ΔG) during a process is related to the change in enthalpy, or change in total energy (ΔH), change in entropy (ΔS), and temperature in kelvin (T)
- ΔG = ΔH - TΔS

Exergonic Reaction
A spontaneous chemical reaction, in which there is a net release of free energy

Endergonic Reaction
A nonspontaneous chemical reaction, in which free energy is absorbed from the surroundings

A defining feature of life is that metabolism is _____ at equilibrium.
Never




















