end product inhibits earlier step in synthesis. Maintains constant chemical condition
move matter against opposing forces
potential energy available for release in a chemical reaction
the study of energy transformations that occur in a collection of matter
unable to exchange energy or matter with its surroundings
energy and matter can be transferred between the system and its surroundings
first law of thermodynamics
principle of conservation of energy--can be transformed or transferred but cannot be created or destroyed
second law of thermodynamics
every energy transfer or transformation increases the entropy or disorder of the universe. For a process to occur spontaniously it must increase the disorder of the universe
spontantious and nonspontanious processes
spontanious is energetically favorable. Nonspontanious will not happen without energy input
the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system (delta G=delta H-TdeltaS). Processes with negative deltaG are spontanious. High G wants to be lower G--more stable. A process can perform work and is spontanious only when moving towards equilibrium
3 types of work of cells
chemical (pushing of endergonic)
transport (pumping of substances against)
mechanical (beating of cilla, muscle cells)
use of an exergonic process to drive an endergonic one
ATP (adenosine triphosphate) structure and hydrolysis
sugar ribose with nitrogenous base adenine and 3 phosphate groups (used to make RNA). Hydrolysis makes it P + ADP by breaking off a phosphate. spontanious, releases lots of energy. Couples with endergonics to make exergonic couples
macromolecule that acts as a catalyst, a chemical agent that speeds up a reaction without being consumed by it. Specificity results from shape. Shape is fluid-ish.
initial investment of energy for starting a reaction. Enzymes lower this barrier.
the reactant an enzyme works on
when the enzyme binds to its substrate.
the specific portion of the molecule that binds to the substrate
substrate-enzyme fit that holds substrate in the best possible position for reaction. Substrate is held by hydrogen and ionic bonds, and turned into products by R-group interactions
Enzyme mechanisms to speed reaction
hold two molecules in proper orientation
stretch or bend molecule into optimal shape
provide conducive microenvironment
direct participation of active site in reaction. Enzyme is restored afterwards.
saturated enzymatic reaction
So many substrate molecules exist that all enzyme active sites are busy. Reaction cannot speed up more without more enzymes.
optimal conditions for enzymes
rection increases with increasing temperature as molecules move faster until heat interferes with bonds and eventually denatures protein. pH is the same.
nonprotein helpers for catalytic activity
an ORGANIC nonprotein helper for catalytic activity
chemicals that stop enzymes. Covalent bonds mean irreversable inhibition
reversable enzyme inhibitor that resembles the substrate and competes for admission to active site. Can be overcome by increasing substrates
bind to allosteric site
a protein's function at one site is affected by the binding of a regulatory molecule to a separate site.
activator vs inhibitor
molecule binds to a regulatory or allosteric site in to hold it in active or inactive form. Will affect all subunits on enzyme
amplifies the response of enzymes to substrates. A substrate bonding to an active site triggers a shape changes, increasing catalytic activity.
a metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway
a catabolic process that is a partial degredation of sugars/organic fuels without oxygen. occurs in cytosol. Alcohol and lactic acid types. Produce much less ATP than aerobic
C6H12O6 + 6O2 ---> 6H2O + 6CO2= -deltaG, so exergonic
Where does glycolyis occur
glycolysis Carbon activity
1 glucose in, 2 pyruvic acid out
Energy product gain of glycolysis
2 ATP and 2 NADH
an oxidation-reduction reaction where there is a transfer of electrons from one reactant to another. Can also work with unequal sharing--oxygen is reduced from O2 to 2H2O because it has closer bonds with the elctrons in a polar setting
loss of electrons
gaining of electrons (O2-H2O)
electron donor in redox reaction
O2's role in cellular respiration
terminal electron acceptor
4 steps of cellular respiration
glycolysis, pyruvate oxidation, citric acid cycle, oxidative phosphorylation and chemiosmosis
cytosol--breaks glucose into 2 molecules of pyruvate
ATP synthesis powered by redox reactions of the electron transport chain.
site of oxidative phosphorylation (electron transport chain and chemiosmosis)
inner membrane of the mitochondrion
enzyme transfers a phosphate group from a substrate molecule to ADP. Happens in glycolysis and citric acid cycle
How much ATP per glucose
oxygen is a reactant
net glycolysis inflow and outcome
1 glucose in, 2 pyruvate and 2 water out
2 ATP in, 4 ATP out= 2 ATP
2NAD+, 4 electrons and 4 protons in, 2 NADH and 2 protons out
where does aerobic or anaerobic respiration begin?
after pyruvate formation (in the cytosol)
what are the types of fermentation
alcohol and lactic acid. Ethanol done by some bacteria and plants. All occur in cytosol.
what is champagne an example of
alcoholic fermentation. The bubbles are carbon dioxide. Must be made without oxygen in a closed container.
what are the products of pyruvate oxidation
for 2 pyruvate (2 per 1 glucose) 2 CO2 released, 4 NADH are made, 2 Coenzyme A are consumed, 2 Acetyl CoA (exergonic, high potential energy) are produced.
where does pyruvate oxidation/Acetyl CoA formation occur
Pyruvate begins oxidation in the cytosol and becomes Acetyl CoA in the matrix of the mitochondrion after moving across 2 membranes.
citric acid cycle generates:
3 NADH, 1 ATP and 1 FADH per turn (so double that b/c 2 pyruvate per glucose) and gives off 2 CO2.
The citric acid cycle has ____ steps
Where does the citric acid cycle occur
Where does oxidative phosphorylation occur
Inner mitochondrial membrane (cristae)
Purpose of electron transport chain
to pump protons out of the cell to make pH of intermembranal space more acidic. pH gradient is used to make ATP with ATP Synthase (chemiosmosis)
superhighway of metabolism
what is the electron transport chain
a collection of molecules embedded in the inner membrane of the mitochondrion in eukaryotic cells
Where do the first electrons for the electron transport chain come from
At the end of the electron transport chain
Oxygen accepts the two electrons, reducing, and picks up two protons in the solution and forms water
the protein in the inner membrane of the mitochondria that makes ATP from ADP and phosphate.
what is the net product of oxydative phosphorylation
what powers ATP synthase?
the difference in the concentration of H+ on either side of the inner mitochondrial membrane tries to equalize, spinning the rotor to do work
energy in the form of a hydrogen ion gradient across a membrane drives cellular work such as the synthesis of ATP
what makes the proton gradient in the mitochondria?
electron transport chain puts more H+ between the inner and outer mitochondrial membrane and less inside the cristae using electrons from NADH and FADH
why does FADH produce less energy than NADH
enters the electron transport chain at a lower place.
total ATP output from one glucose molecule
oxidized to 6CO2, 30-32 ATP
difference between anaerobic respiration and fermentation
an electron transport chain is used in anaerobic respiration but not in fermentation
How does anaerobic respiration differ from aerobic?
Oxygen is not the electron acceptor at the end. Sulfer can be, or something else
the continuous generation of ATP by the substrate-level phosphorylization of glycolysis.
lactic acid fermentation releases
lactate No CO2
similarities and differences in respiration types
All use glycolysis to make pyruvate and use NAD+ as an electron acceptor. They differ in how to oxidize NADH back down.
cannot carry out aerobic respiration or survive in the presence of oxygen.
can survive with either fermentation or respiration
process during dygestion of proteins where amino groups are removed prior to entering glycolysis
breaks down fatty acids into two-carbon fragments which enter the citric acid cycle as acetyl CoA, generating NADH and FADH2
equation for photosynthesis
6CO2 + 6H2O --chll a--> C6H12O6 + 6O2
exact opposite of cellular respiration. Endergonic, catabolic.
self-feeders, like plants. "producers" of the biosphere
live on compounds produced by other organisms
site of photosynthesis
tissue in the interior of the leaf, where chloroplasts are usually found
microscopic pores where CO2 enters and oxygen exits.
2 membranes surrounding a dense fluid called the stroma. Suspended in the stroma are thylakoids stacked in columns called grana. Inside these is the thylakoid space. The thylakoid membrane has chlorophyll
suspended in the stroma, the membrane that holds the chlorophyll and the space inside, called the thylakoid space.
dense fluid inside the membranes of the chloroplast that suspends the thylakoids
direct product of photosynthesis
oxygen and a 3-carbon sugar that can be used to make glucose. water is on both sides of the equation--12 go in and 6 come out.
redox reaction of photosynthesis
CO2 reduces to C6H12O6 and H2O oxidizes to O2. Process requires energy and is endergonic
two stages of photosynthesis
light reactions and calvin cycle
takes in H2O, light, NADP+, ADP and Phosphate ion and give off NADPH, ATP and O2.
light energy using chemiosmosis to power the addition of a phosphate to ADP
initial incorporation of carbon into organic compounds
site of light reactions
thylakoids of the chloroplast
site of calvin cycle
How do protons effect pH
more protons make pH more acidic (lowers).
distance between the crests of electromagnetic waves
entire range of radiation
380-750n. violet is 380-red is 750
the particles of light. Not really particles, but each has a fixed amount of energy--the shorter the wavelength, the more energy
particles that absorb visible light
light absorption versus wavelength graph
participates directly in light reactions
accessory pigments and use
chlorophyll b and the carotenoids. Photoprotection--sunscreen and sometimes energy transfer
which lights are best for photosynthesis?
violet-blue and red. Green is the least effective
profiles the relative effectiveness of different wavelengths of radiation in driving a process. The living version of the absorption spectrum
Englemann 's photosynthesis experiment
bacteria to measure the rates of photosynthesis in algae. Match to action spectrum.
when the energy harvested from the sun in chloroplasts has no where to go, it will give off light and heat
carotene and xanthophyll
separating chemicals but putting them in a nonpolar solution and seeing who travels the furthest (most nonpolar)
reaction center complex
holds the special chlorophyll molecules (P680 and P700) and the primary electron acceptor.
light harvesting complex
has the regular chlorophyll a, b and carotenes bound to proteins.
the reaction center complex surrounded by the light-harvesting complexes. There are 2 in photosynthesis, #2 comes first. In the thylakoid membrane
why 680 and 700?
those are their favorite wavelengths
linear electron flow
light excites the electrons of P680, so they go to the electron acceptor, down the transport chain, making ATP, falling further to P700, where they get exited again by light and fall down another chain to make NADPH. Photosystem II breaks water to get electrons back
cyclic electron flow
only uses photosystem I, only makes ATP, does not generate NADPH or oxygen
how are chloroplasts and mitochondria similar?
Both have double membrane and DNA, both generate ATP with an electron transport chain pumping protons across a membrane then synthesizing ATP with the resulting gradient (chemiosmosis)
where is the proton gradient in photosynthesis
the thylakoid space functions as the H+ reservoir. ATP is synthesized as hydrogen ions diffuse back to the stroma through ATP synthase, so ATP forms in the stroma where the Calvin cycle is
uses the energy of ATP and NADPH to reduce CO2 to sugar
starting material is regenerated after molecules enter and leave the cycle (calvin and citric acid)
Differences between Calvin and Citric acid cycles
citric acid cycle is catabolic and Calvin cycle is anabolic.
three phases of the calvin cycle
carbon fixation, reduction and regeneration
calvin cycle carbon fixation phase
incorporates CO2 molecule, attaches it to RuBP (5-C sugar). Enzyme that catalyzes is Rubisco. Product is two molecules of a 3-C sugar
enzyme that fixes carbon into RuBP in the first step of the Calvin Cycle. Most abundant protein in chloroplasts and possibly on earth.
Calvin cycle reduction phase
3-C sugar gets an extra phosphate from ATP and gets reduced by NADPH to make 3-C sugar. One gets released for use in the plant and 5 go back to regeneration phase
Calvin cycle regeneration phase
5 2-C sugars are rearranged into 3 5-C RuBPs.
Calvin cycle in and out
3 CO2 in = 1 G3P out
9ATP in = 9 ADP out
6 NADPH in = 6 NADP+ out
when stomata close to conserve water, oxygen builds up and carbon dioxide runs down, plants use (rubisco fixes) O2 instead of CO2 and produce a 2-C compound instead. Peroxisomes and mitochondria split this compound, releasing CO2. Produces no ATP but uses some, and produces no sugar. Releases CO2 the plant would otherwise use.
Uses of wasteful photorespiration
protects against excess light. C4 plants and CAM plants have found ways to mostly avoid it
Rice, wheat and soy.
sugarcane and con
C4 plant leaves have bundle-sheath cells and normal mesophyll cells. Calvin cycle is in chloroplasts of bundle-sheath. PEP carboxylase in mesophyll cells fixes CO2 into a 4-C product and exports through plasmodesmata to bundle-sheath and Calvin.
tightly-packed sheaths around veins of leaf in C4 plant. Where Calvin cycle takes place in C4. Also use cyclical electron flow with no photosystem II to generate ATP.
C4 mesophyll cells
have PEP carboxylase enzyme that fixes CO2. Export CO2 and 4-C compound to bundle-sheaths through plasmodesmata so rubisco will not fix oxygen.
enzyme in mesophyll cells of C4 plants that makes a 4-C product out of CO2. Higher affinity for CO2 than rubisco and none for O2. Can fix C when stomata are closed. Can be thought of as CO2 pump into bundle-sheath powered by ATP
CAM plant adaptations
open stomata during night and close during day, storing CO2 products in vacuoles. Have Calvin cycle and carbon fixation in same cell at different times.