what are the 2 ways organisms harvest energy fromt heir environments
- phototroph: from sun
- plants, convert sunlight energy from CO2 and water into sugar and O2 - chemotroph: from chemical compounds
- animals, ingest other organisms and break them down into CO2 and water
what are the 2 ways organisms are classified based on their source of carbon
- autotroph
convert CO2 into glucose, make their own - heterotroph
ingest other organisms/molecules, unable to convert CO2
what is metabolism
chemical processes that occur in a living organism to maintain life
includes building up/breakdown of chemical compounds, allowing energy to be harnessed/released
continuously occuring in cells
linked in such a ay that products of one reaction are reactants of the next - forming pathways
what are the 2 branches of metabolism
anabolism and catabolism
what is anabolism
building of molecules from smaller units
requires input of energy (ATP)
what is catabolism
breakdown of molecules into smaller units to produce energy (ATP)
what are the 2 types of energy
potential - energy that is stored
kinetic - energy of motion
what is chemical energy
chemical bonds between pairs of atoms in a molecule hold onto a form of potential energy
how are bond strength and potential energy linked
strong bonds = less potential
weak bonds = more potential
what is ATP composed of
adenine
ribose (5 carbon sugar)
3 phosphate grps
if there are less than 3 phosphates with adenine and ribose:
2 P grps = ADP
1 P grp = AMP
what are examples of cellular work
DNA, RNA and protein synth
vesicle mobvement in a cell
pumping substances across membranes
breaking down fats to release energy
breaking down proteins into amino acids
oxidizing sugars to prod ATP
how much potential energy does ATP have? why?
high potential energy
bonds between phosphate grps are weak - where chemical energy is held
what is thermodynamics
study of changes in energy taht accompany events in the universe
allows us to preduct direction that events will take and whether input of energy is required
what is the 1st law of thermodynamics
energy can be neither created nor destroyed
energy can be converted from one form to another (ex sunlight into chemical energy)
what is the 2nd law of thermodynamics
events in the universe have direction -> proceed froma higher energy state ot a lower energy state
events are thermodynamically favourable and said to be spont. -> no input of external energy
results in a reduction in the amnt of useable energy -> energy transfromations are not 100% efficient
what is Gibbs free energy
amnt of energy in a system available to do work
ΔG - difference in Gibbs free energy between reactants and products of a chemical process
if the reactants have more free energy than the products:
ΔG is negative
thermodynamically favourable -> exergonic
energy is available for use in other processes, gives energy
graph goes from up to down
if the products of a reaction have more free energy than reactants:
ΔG is positive
thermodynamically unfavourable -> endergonic
needs input of energy
in a graph, amnt of energy required is from reactants to products (down to up)
what si the difference between endergonic and exergonic reactions
endergonic -> require energy
(down to up)
non-spont
+ΔG
exergonic -> release energy
(up to down)
spont
-ΔG
what is the formula for state of Gibbs free energy
Total energy (H) = energy available to do work (G) + energy lost to entropy (S)
ΔG = ΔH - TΔS
H = total energy
G = energy available to do work
S = energy lost to entropy/disorder
T = absolute temp in Kelvin
what happens when ATP is hydrolyzed
reaction of ATP with water is exergonic (spont) -> releases energy (-ΔG)
at physiological pH -> phosphate grps in ATP are negatively charged and resist one another
compared to ATP, which has 3 P grps, ADP contains 2 = lower potential energy
what is activation energy
chemical transfromations req the breakage of certain covalent bonds within reactant
reactnats must contain sufficient kinetic energy to overcome activation energy barrier: (EA)
enzymes catalyze reactions by decreasing magnitude of EA barrier -> reaction can proceed
how are chemical reactions catalysed
catalyzed by proteins called enzymes
active site of an enzyme is formed by the assembly of certain amino acids in 3D structure
enzyme active site binds substrate(s) and converts to product(s)
active site binds substrate(s) and helps to stabilize transition state -> lowers activation energy
