Please enable JavaScript.
Coggle requires JavaScript to display documents.
CHAPTER 8 - Coggle Diagram
CHAPTER 8
AN ORGANISM'S METABOLISM
METABOLISM
All chemical reactions in an organism
Organized into metabolic pathways
Each step catalyzed by a specific enzyme
METABOLIC PATHWAY
stepwise process (molecule converted to product)
example
A-B-C-D (each step has it's own enzyme)
purpose (manage material and energy resources)
CATABOLIC PATHWAYS
break down complex molecules (release energy)
example
cellular resparation - glucose - CO2 + H2O
exergonic (energy release)
ANABOLIC PATHWAYS
build complex molecules - requires energy
example
amino acids - proteins
endergonic (energy release)
ENERGY AND THERMODYNAMICS
ENERGY
capacity to cause change or do work
two main forms
kinetic
potential
KINETIC ENERGY
energy of motion - water moving through dam, diver falling
thermal energy; movement of atoms, heat = transfer of thermal energy
POTENTIAL ENERGY
energy based on location or structure
chemical energy: stored in molecular bonds (e.g, glucose0
1ST LAW OF THERMODYNAMICS
energy can not be created or destroyed
its transformed or transfered
2ND LAW THERMODYNAMICS
every energy transfer increases entropy (disorder)
example
breaking objects, diffusion, melting ice
ENTROPY EXAMPLES
bear eating - releases CO2, H2O, and heat - increases disorder
cell maintains order by creating disorder elsewhere
FREE ENERGY AND SPONTANEOUS REACTIONS
FREE ENERGY (G)
portion of system's energy that can do work
Gibbs free energy - determines if reaction is spontaneous
ΔG = G(FINAL) - G(INITIAL)
negative - spontaneous (exergonic)
positive - non-spontaneous (endergonic)
EQUATION
ΔG = ΔH - TΔS
T = temperature (kelvin)
ΔS = entropy (disorder)
SPONTANEOUS REACTIONS
energy released; products more stable
example
glucose - CO2 + H2O; ink drop spreading in water
NON-SPONTANOUS REACTIONS
require energy input; products less stable
example
synthesis of macromolecules
EQUALIBRIUM
ΔG = 0 - no net change; most stable state
EXAMPLES/ANALOGIES
diver on platform (high G) - water (low G)
concentrate dye (high G) - dispersed (low G)
ATP POWERS CELLULAR WORK
ATP
main energy currency of the cell
made of ribose, adenine, and three phosphate group
HYDROLYSIS
ATP - ADP + Pi + energy released
energy used to drive cellular work
COUPLING
exergonic reaction ( ATP breakdown) drives endergonic reactions
example
building proteins or sugars
REGENERATION OF ATP
cellular respiration: uses food energy to add phosphate to ADP
continuous cycle - like recharging a battery
CELLULAR WORK
mechanical - motor proteins "walk" on cytoskeleton
transport - pumps ions across membranes
chemical - builds macromolecules
ENZYMES SPEED UP METABOLIC REATIONS
ENZYMES
biological catalysts that lower activation energy (Ea)
speed up reactions without being used up
ACTIVATION ENERGY
energy needed to start a reaction (the "push)
enzymes make this barrier smaller
EFFECT ON ΔG
enzymes do not can age ΔG
only makes spontaneous reactions faster
SPECIFICITY
each enzyme fits one substrate like a lock and key
REGULATION
cells control enzyme activity to balance metabolism
FEEDBACK INHIBITION
end product bind to enzyme - pathway turns off
example
isoleucine shuts down the first enzyme in its synthesis
PURPOSE
prevents waste; saves energy and materials
COUPLED REACTIONS AND REAL WORLD EXAMPLES
COUPLED REACTIONS
exergonic and endergonic processes linked together
example
ATP hydrolysis powers glutamine formation from glutamic acid + ammonia
THERMOS EXAMPLES
closed system - energy trapped - equilibrium reached
ORGANISM EXAMPLE
open system - constant energy input and output - maintains life
BEAR EXAMPLE
catabolic reactions in bear release energy and increase entropy