Studied by 23 people
determination of if rxn occurs
environmental factors
catalysts definition
substances that accelerate chemical rxns w/out being changed
Enzymes are…
proteins and follow rules of protein construction (primary, secondary, tertiary structure)
enzyme conformed =
physical location for reactant molecules to attach to (substrates)
interaction b/w enzyme & substrate
shape dependent; substrate properties and shape must be compatible w/active site
substrate relation
closely related based on highly similar structure and properties
enzymes w/decomposition rxns
interact with 1 substrate & produce lots of products
enzymes catalysing synthesis rxn
accepts many substrates & product one product
substrate bonding to active site triggers…
shape change
shape change results in…
stress on bonds w/in substrate = bonds weakened and less potential energy required for rxn
enzyme not changed by rxn
concentration of substrate/enzyme changes as time passes
as rxn progress =
substrate molecules are less available and slows rxn down
every enzyme has set environment conditions where it functions most effectively
temperature; pH; concentration of enzyme &/or substrate; concentration of other solutes; presence of cofactors and coenzymes
cofactor
substance other than substrate whose presence is required for enzyme function
coenzyme
organic non-protein based compound that binds to enzymes reversible assisting in function
denatured
enzyme lost its function conformation bc of change in environmental conditions
change in enzyme shape =
down or loss of enzymatic activity
weaker interactions/loss of shape
more likely to be interfered/prevents enzyme function
allosteric site (in some enzymes)
regulatory molecules binds and locks enzyme into confirmation → regulating an enzyme
enzyme action halted by…
blocking active site
competitive inhibition
involves molecule (non-substrate) binding to active site (no chem-rxn and blocks substrate)
non-competitive inhibition
form of allosteric regulation → occurs when molecules binds to enzyme somewhere other than active site = conformational change to enzyme
biochemical pathways
involve series of enzymes functioning like relay-race
feedback inhibition
end product reversibly binds to allosteric site of 1st enzyme in pathway → changes first conformation = prevents initial rxn occuring
metabolic pathways
pathways used to convert substrates into products
drivers of pathways
enzymes → proteins that work to assist chemical rxns by building or breaking down molecules
rate of reaction
can speed, slow, or stop based on cell needs
allosteric site role
prevents cells from wasting resources/energy to maintain homeostasis
Greater concentration of substrate than competition inhibitor
rxn occurs
competition inhibitor has higher concentration
rxn halted
stages of photosynthesis
light-dependent rxns & calvin cycle
consumers
consuming/ingesting organic molecules for energy
producer
taking energy and forming into more energy
energy
can’t be created or destroyed; only transferred & transforms as moves from one organism to another
energy forms
light; gravitational; kinetic (motion); nuclear
chemical energy
a form of potential energy; result of molecular structure
law of thermodynamics
study of energy transformations
first law of thermodynamics
energy cannot be created or destroyed
second law of thermodynamics
less energy is available after each transformation (release of heat); transformations favor a disorderly state
entropy
measures the disorder of a system (relative); use as little energy as possible; related to building and breaking molecules
catabolic reaction
large molecules broken into small products
anabolic reaction
smaller reactants made into larger products
free energy
energy available for a system to do work
catabolic rxn ex.
glucose → O & H molecules
anabolic rxn. ex.
O & H molecules → glucose
chemical rxns and free energy
chemical rxns change amount of free energy in a system
-ΔG
spontaneous rxn & release of energy
+ΔG
non-spontaneous rxn & requires energy
when is equilibrium achieved
when rates of forward & reverse rxns are identical
why is equilibrium never achieved in living system
constant supply of matter/energy input
metabolic pathway
pathways linked together by using products from one rxn as reactants of another
words associated with breaking down molecules
catabolic; +ΔS (increasing entropy); exergnoic (releasing energy); -ΔG (decreasing free energy); spontaneous
words associated with building up molecules
anabolic; -ΔS (decreasing entropy); endergonic (storing energy); +ΔG (increasing free energy); non-spontaneous
chemical rxns involve…
all chemical rxns involve breaking/building chemical bonds by transferring of electrons
reduced atoms
atoms receiving electrons
oxidized atoms
atoms giving electrons r
redox…
can’t occur independently of each other
whether rxn occurs =
release or storage of energy depends on bond energies of reactant and product
ATP hydrolyzed
free phosphate ion bonds to reactant molecules (phosphorylation)
ADP → ATP
addition of phosphorus ion
Phosphorylation
addition of phosphoryl group to a molecule
photosynthesis captures energy from ….. and produces….
sun; sugars
what did photosynthesis first evolve from
prokaryotes; evolved in organisms like cyanobacteria
evolution of photosynthesis contributed to…
oxidation of atmosphere
visible light is produced by sun and used as energy
1% of sunlight is used for photosynthesis
pigments
molecules that absorb some wavelengths of light and reflect others to appear as a color
chlorophyll molecule has a
high concentration in plant = green color
chlorophyll A
primary pigment responsible for initiating rxns of photosynthesis → absorbs blue and red wavelengths
light energy from sun drives…
anabolic endergonic rxns
where is chloroplast density hightest?
on the top surface of the leaf in mesophyll cells to be efficient w/using light energy
stomata
pores on bottom of the leaf that open and close to regulate exchange of gases (CO2 in and O2 out)
chloroplast
stroma; thylakoids; photosystems; thylakoid space; granum
stroma
large internal space where Calvin Cycle occurs
thylakoid
membrane bound structure stacked on each other and have photosystems & electron transport chains; location of dependent rxns
photosystems
clusters of photosynthetic pigments embedded in membrane
thylakoid space
internal space of thylakoids and interconnected w/other thylakoids; provides a concentration gradient of H+ (protons) to be est.
granum
stack of thylakoids
light dependent rxns
light energy to chemical energy
Photosystem 2
lgiht strikes photosynthetic pigments embedded in thylakoid membrane and light is transferred
E- removed from cholorphyll A and boosted to highter energy level → replaced with E- from H2o
oxygen gas is produced as waste
Electron transport chain
links photosystem 1 & 2 by series of proteins embedded in TK membrane
ETC processes
E- travel from protein to protein in TK in ETC (pumps H+ to in stroma)
ATP is generated as E- are transferred
ETC processes
proteins of ETC use energy from E- transfer to actively transport protons from stroma into TK space; concentration gradient of protons = facilitated diffusion of protons back into stroma thru ATP synthase
photosystem 1
E- from ETC deposited @ chlorophyll A
E- boosted to higher energy level by light
2 E- & proton transferred to E- carrier (NADP+ → NAPDH)
reactants and products of dependent rxns
water and o2 gas; ATP and NADPH are NOT net products
atp and nadph from dependent =
provides energy to power calvin cycle
napdh deliver electrons from
h2o to form new covalent bonds to build organic molecules
3 stages of calvin cycle
carbon fixation; reduction; regeneration
carbon fixation
co2 from atmosphere enters stomata
Rubisco joins co2 to acceptor → RuBP
RuBP added to crbon = 6C 2 phosphate molecule that is unstable = 6 molecules each with 3C and 1 phosphate
RuBP
five carbon molecules with two phosphates
Reduction
ATP broken down; gives 2nd phosphate to 3c molecules
NAPDH delivers E- to 3c molecules → rearranged and lose phosphate = 6 glyceraldehyde 3 phosphate molecules
1 G3P molecule exits calvin cycle and remaining 5 complete it
after reduction NADP+ and ADP and free phosphates
returns to dependent rxns for reconstruction to be sent back and used again
Regeneration of CO2 acceptor (RuBP)
rearranges 5 G3P molecules into 3 molecules of RuBP to continue calvin cycle
1 full completion of photosynthesis =
1 G3P molecule
G3P can be used as reactant to form…
biochem pathways for mono/polysaccgarudes; mentose sugars; fatty acids; glycerol; amino acids
photorespiration
CO2 levels fall, O2 levels rise = rubisco fixes oxygen to RuBP
Stomata is important for…
exchange of gases bus especially H2O evaporate from plants
why do plants regulate stomata
to slow/speed evaporation process (ex. hot dry days, plants close stomata to avoid water loss)
why is photorespiration unstainable over long periods?
because it won’t make enough G3P to survive
alternatives to C3 photosynthesis
C4 plants - spatial separation; CAM plants - Temporal seperation
Spatial Separation - C4 Plants
fixes co2 to organic acid
shipped off to another cell for rest of calvin cycle
*bc carbonfixation and calvin cycle occur in two different locations (cells)
