chapter eight part one Flashcards
metabolism
the totality of an organism’s chemical reactions
metabolic pathway
where a specific molecule is altered in a series of define steps, resulting in a certain product
- each step catalyzed by certain enzyme
catabolic pathways
degradative process (breakdown)
- ex. cellular respiration
anabolic pathways
building complex molecules (biosynthetic)
- ex. synthesis of protein from amino acids
bioenergetics
the study of how energy flows through living organisms
energy sources
ATP, gradient, sunlight, reduced molecule energy (glucose)
why ATP?
- same amount of energy as other nucleotides
- God gave it
types of energy
kinetic, heat/thermal, potential, chemical
energy
capacity to cause change
kinetic energy
energy associated with relative motion of objects
heat/thermal energy
kinetic energy associated with random movement of molecules
heat
thermal energy in transfer from one object to another
potential energy
energy possessed because of location and structure
chemical energy
potential energy available for release in a chemical reaction
thermodynamics
study of energy transformations that occur in a collection
First Law of Thermodynamics
energy can be transferred and transformed, not created or destroyed
- energy is constant
Second Law of Thermodynamics
energy transfer increases entropy
entropy
measure of disorder and randomness
free energy
energy that is available for work (G)
equation for free energy
delta G = delta H - T(delta S)
- total energy minus disorder
delta G
change in free energy (Gibbs)
T
absolute temperature (K)
delta S
change in system’s entropy
delta H
change in system’s enthalpy (total energy)
does free energy increase or decrease in a spontaneous process?
decrease
spontaneous process
energetically favorable, occurs without input of energy
a highly ordered system is
unstable
in a spontaneous reaction, delta G has a _______ value
negative (decrease in free energy)
at equilibrium, delta G =
0 (no net change in system)
exergonic reaction
releases energy
- G is negative
- occur spontaneously
endergonic reaction
needs energy
- G is positive
- non spontaneous
metabolic disequilibrium
defining feature of life, organisms never at equilibrium
cell is dead at
metabolic equilibrium
what does breaking bonds require?
energy
if chemical process is exergonic, then reverse process is
endergonic
3 types of cellular work
- chemical
- transport
- mechanical
chemical cellular work
pushing of endergonic reactions, synthesis of polymers from monomers
transport cellular work
pumping of substances across membranes against direction of spontaneous movement
mechanical cellular work
beating of cilia, contraction of muscle cells, movement of chromosomes
energy coupling
use of exergonic process to drive endergonic one
- ATP driven
ATP composition
ribose + adenine + 3 phosphate groups
hydrolysis
addition of water molecule to break terminal phosphate bond
- ATP to ADP
- exergonic reaction, releases 7.3 kcal/mol hydrolyzed
kcal/mol
delta G = 7.3 kcal/mol (standard conditions for ATP)
ATP + H20 =
ADP + Pi + energy
(inorganic phosphate)
where does regeneration of ATP occur?
mitochondria
phosphorylation of ADP
additionally of phosphate to ADP
- energy comes from catabolism (exergonic) in cell
catalyst
chemical agent that speeds up reactions without being consumed
enzymes
macromolecule that acts as a catalyst
activation energy
initial energy of investment for starting a reaction
- contort reactant molecules so bonds break
what can an enzyme not change?
delta G for reaction or make endergonic reaction exergonic
substrate
reactant an enzyme acts on
enzyme-substrate complex
when enzyme binds to substrate
- while bound, substrate converted to product
active site
allows binding of substrate
induced fit
active site clasps to substrate
what type of bonds connect the substrate and enzyme?
hydrogen and ionic
how catalysis occurs in enzyme’s active site
- R groups of amino acids catalyze conversion of substrate to product
1. substrate fits into active site
2. substances held by weak interactions
3. E(A) lowered, reaction speeds up
4. substrates converted to products and released
factors on enzyme activity
temperature, pH, cofactors, coenzymes
temperature and enzymes
rate of reaction increases w/ increasing temperature up to point, above that hydrogen/ionic bonds disrupted and enzyme denatures
pH and enzymes
6-8, but some exceptions
cofactors
non-protein helpers of catalytic activity
- inorganic (metal ions)
coenzyme
organic molecule that helps catalytic activity
when can an endergonic reaction be spontaneous?
when it is coupled with an exergonic reaction
