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What is Metabolism?
refers to all the chemical reactions that occur in a cell, usually to transform matter and energy
What are metabolic pathways?
Reactions which usually occur in step-by-step sequence
eg. Product of one is the reactant in the next
What are anabolic reactions?
Each reaction is catalyzed by an enzyme that builds large molecules
Small → Big (Build)
ex. photosynthesis
What are catabolic reactions?
when large molecules are broken into smaller products
Big → Small (Destroy)
Catastrophic
Ex. Cellular respiration
What is Energy?
the capacity to do work
What is Kinetic energy?
the energy of motion
What is potential energy?
stored energy
What does the cell require?
the transformation of potential energy into kinetic energy
ex. cilia moving, active transport and protein pumping
What is bond energy?
The energy required to break (or form) chemical bonds
What is an endothermic reaction?
when a chemical bond is broken between two atoms, energy is used
What is exothermic reaction?
when a chemical bond forms between two atoms, energy is released
What is crucial for respiration and photosynthesis?
endothermic and exothermic reactions are crucial in the production of energy and the absorption of energy
General Info on Bond Energy:
energy is always released when a bond forms, free (unbonded) atoms can be considered to have more chemical energy than any compound.
What is Thermodynamics?
the study of energy changes in a system
What is the First Law of Thermodynamics?
energy cannot be created or destroyed, but it can be transformed from one type into another and transferred from one object to another
ex. plants can absorb light but they can’t create it.
What is the Second Law of Thermodynamics?
during any process, the universe tends towards disorder
ex. unless you consistently use energy to clean, your room will eventually get dirty
What is an Endergonic Reaction?
The products of the reaction contain more energy than the reactants, and energy must be supplied for the reaction to proceed.
Endothermic reaction - up the hill diagram
What is an Exergonic Reaction?
The products contain less energy than the reactants, and excess energy is released.
Exothermic reactions - down the hill diagram
(exit)
What do spontaneous reactions require?
an initial input of energy, such as a spark to begin them
What is activation energy?
destabilizes the existing chemical bonds
What are enzymes used for?
required to lower the activation energy of a reaction and reduce the amount of time it can take for a reaction to occur.
biological catalyst
what is ATP?
energy released by catabolic reactions is captured in the molecule, and is used to power reactions in a coupled reaction.
bonds between the negative phosphate groups in this molecule contain a large amount of energy
when their bonds are hydrolyzed and broken, they release that stored energy to do work in the cell.
What is a Coupled Reaction?
The use of ATP can be thought of as a cycle
cells use exergonic reactions to provide the energy needed to synthesize ATP from ADP and Pi
They then use the hydrolysis of ATP to provide the energy for endergonic reactions
What are Oxidation-Reduction Reactions
“Redox” reactions
Electrons move between atoms
Loss of electrons is oxidation
Gain of electrons is reduction
LEO the lion says GER
What are Electron Carriers?
redox reactions are coupled reactions
electrons are said to carry reducing power since the reduced form of a molecule (which accepts electrons carrying energy) is always a higher energy level then the oxidized form
compounds that pick up electrons from energy-rich compounds and donates them to low-energy compound
What are the two most important electron carriers?
NAD+ (nicotinamide adenine dinuclotide) & the reduced form NADH
FAD (flavin adenine dinuclotide) & the reduced form FADH2
What is a cofactor?
is a non-protein chemical compound or metallic ion that is required for an enzyme’s role as a catalyst.
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