Ch 3 Flashcards
Potential energy
Stored energy
Kinetic energy
Energy of motion
Chemical energy
Form of potential energy
Most important in body
Used for:
Movement
Molecule synthesis
Establishing concentration gradients
Thermodynamics
Study of energy transformations
Can be changed in forms
First law of thermodynamics
Energy can neither be created nor destroyed, it can only change form
Second law of thermodynamics
When energy is transformed, some energy is lost as heat
Usable energy decreases
Metabolism
All biochemical reactions in living organisms
Chemical reactions
Occur when chemical bonds in existing molecular structure are broken
Decomposition reaction
Initial large molecule is broken down into smaller structures
Aka catabolism
Synthesis reaction
Two or more structures combined to form a larger structure
Aka anabolism
Exergonic reaction
Reactants have more potential energy within their chemical bonds than the products
Energy is released
Endergonic reaction
Reactants have less potential energy
Energy must be “put in”
Activation energy
Energy required to break existing chemical bonds
Determines reaction rate
Enzymes
Catalysts that accelerate normal physiologic activities
Decrease activation energy of cellular reactions
Increase rate of product formation
Location of enzymes
Within cells
Plasma membrane
Some secreted from cell
Enzyme catalysis
- Substrate enters active site, forming enzyme substrate complex
- Enzyme changes the shape slightly (induced fit model)
- Change in enzyme shape stresses chemical bonds, permitting new bonds to be formed
- Products are released; enzyme may repeat process (glucose and galactose released)
Cofactors
Molecules or “helper” ions required to ensure that a reaction occurs
Associated with particular enzyme
Non protein organic and inorganic structure
Reaction rate
Increase in enzyme concentration
Increase in substrate concentration
3D shape
pH 6-8
Saturation
So much substrate is present that all enzyme molecules are engaged in reaction
Inhibitor
Bind enzymes and prevent enzymatic catalysis
Prevent overproduction of product
Release of inhibitor allows it to function and catalysis continues
Competitive inhibitor
Binds to active site
Completes for occupation
Non competitive inhibitor
Do not resemble substrate
Bind to site other than active site (allosteric site)
Aka allosteric inhibitors
Cellular respiration
Multistep metabolic pathway where organic molecules are broken down in a controlled manner by a series of enzymes
Potential energy released
Energy used to make ATP
Oxygen required
Focus on glucose
Four stages of glucose oxidation
Glycolysis (cytosol)
Mitochondria:
Intermediate stage
Citric acid cycle
Electron transport chain
