Unit 3 - Cellular Energetics Flashcards
metabolism
- the totality of all the chemical reactions in an organism
ex: aerobic cell respiration
aerobic cellular respiration
- a combination of the following: glycolysis, kreb cycle, electron transport chain
metabolic pathway
- different reactions that happen in a specific order; one molecule is turned into a product for the next reaction
- the product of one reaction will be the substrate of the next reaction
ex: adp -> atp
glycolysis reaction: 2 parts
glucose -> pyruvate
H2O reaction: 3 parts
H2O -> H+, H+, O, 2e- -> NADPH
2 types of metabolic pathways
- anabolic
- catabolic
anabolic
- “building”
- synthesis
ex: ADP -> ATP
catabolic
- break molecules down
ex: ATP -> ADP
kinds of reactions
endergonic and exergonic
endergonic
- products have more energy (PE) than the reactants
ex: ADP -> ATP - anabolic pathway
exergonic
- products have less energy than the reactants
ex: ATP -> ADP - catabolic pathway
ex: glucose -> pyruvate
endergonic reactions: spontaneity
reaction is not spontaneous
exergonic reactions: spontaneity
reaction is spontaneous
ATP
- adenosine triphosphate
- adenosine = nucleotide (a)
- ribose sugar
- 3x phosphate
ADP
- adenosine diphosphate
- ADP -> ATP
- uncharged, less PE
GTP
- Guanine Tri Phosphate
- GDP -> GTP
- GTP -> GDP
^^ cell signaling
why are plants amazing?
they build themselves from CO2 in the atmosphere
photosynthesis
- metabolic pathway that uses CO2, H2O, and sunlight to produce sugar (G3P/glucose) and O2
plant structure: stomates
- O2, CO2 go in and out
- H2O goes out
plant structure: chloroplasts
do photosynthesis
plant structure: palisades layer
where chloroplasts are found
plant structure: cuticle
plant structure: thylakoids
location of light reaction
plant structure: granum
stack of thylakoids
plant structure: stroma
liquid portion of chloroplast
- location of Calvin Cycle
reduction
- gain e-
- gain H
ex: NADP+ -> NADPH
oxidize
- lose e-
- lose H ion
- NADPH -> NADP+
what is meant when we say that glucose is oxidized into carbon dioxide in cellular respiration
glucose loses an e- and H
light reaction
- AKA light dependent reaction
dark reaction
- light independent reaction
- AKA calvin cycle
what goes “in” for light reaction
light, H2O, ADP, NADP+
what goes “out” for light reaction
NADPH, ATP, O2
what goes “in” for dark reaction
CO2, ATP, NADPH
what goes “out” for dark reaction
G3P (glucose), ADP, NADP+
G3P is aka as
triose phosphate
electron carriers
- NADP+ -> NADPH
- carries 2 electrons to the calvin cycle
photosystem I
- chlorophyll B
- pigment that captures light
photosystem II
- chlorophyll A
photolysis
- using light to split water
- H2O is oxidized; H2O -> H+, H+, O, 2e-
chemiosmosis
- actively pumping charged ions (H+) across a membrane to be used to produce ATP
photophosphorylation
- using light to make ATP
- ADP + P -> ATP
- electrons are removed from water and passed through PSII & PSI before ending up in NADPH
for an enzyme mediated chemical reaction to occur, what must be compatible
the shape and charge of the substrate must be compatible with the active site of the enzyme
when does denaturation of an enzyme occur
when the protein structure is disrupted, eliminating the ability to catalyze reactions
what can determine how efficiently an enzymatic reaction proceeds?
the relative concentrations of substrates and products
higher environmental temperatures: rate of reaction
Higher environmental temperatures increase
the speed of movement of molecules in a
solution, increasing the frequency of collisions
between enzymes and substrates and
therefore increasing the rate of reaction
competitive inhibitors
bind reversibly or irreversibly to the active site of the enzyme
noncompetitive inhibitors
bind allosteric sites, changing the shape and activity of the enzyme
energy input must ______ energy loss to…
energy input must EXCEED energy loss to maintain order and to power cellular processes
why are energy related pathways in biological systems sequential
- to allow for a more controlled and efficient transfer of energy
- a product of a reaction in a metabolic pathway is generally the reactant for the subsequent step in the pathway
photosynthesis first evolved in
prokaryotic organisms
what was responsible for the production of an oxygenated atmosphere
prokaryotic (cyanobacterial) photosynthesis was responsible for an oxygenated atmosphere
light dependent reaction of photosynthesis involves what?
involve a series of coordinated reaction pathways that capture energy present in light to yield ATP and NADPH, which power the
production of organic molecules
what does chlorophyll do during photosynthesis
During photosynthesis, chlorophylls absorb
energy from light, boosting electrons to a
higher energy level in photosystems I and II
photosystems I & II are embedded in
the internal membranes of chloroplasts and are connected by the transfer of higher energy electrons through the ETC
the formation of the proton gradient is linked to
the synthesis of ATP from ADP and inorganic phosphate via ATP synthase
the energy captured in the light reactions and transferred to ATP and NADPH powers the
production of carbohydrates from carbon dioxide in the Calvin cycle, which occurs in the stroma of the chloroplast
who carries out respiration
every cell of every organism
who carries out photosynthesis
ONLY photosynthetic organisms
photosynthetic prokaryotes carry out photosynthesis where?
on their cell membranes
photosynthetic eukaryotes carry out photosynthesis where?
in chloroplasts
photosynthesis is what type of reaction?
reduction of CO2 into glucose
where does the light reaction of photosynthesis occur
thylakoids
stroma
- like cytoplasm
- calvin cycle
why does a leaf look green?
chlorophyll absorbs (uses) red and blue light and reflects (does not use) green light
what happens to a plant grown under green light?
if a green plant is exposed to only green light, no photosynthesis would occur
2 reactions of photosynthesis
- light reaction
- calvin cycle
light reaction
produces energy rich molecules (ATP and NADPH)
- uses H2O and sunlight
- also produces O2
Calvin Cycle
uses the energy rich molecules that were produced in the light reaction to reduce carbon dioxide to glucose
photolysis
- splitting of water
- electrons from water molecule fill the electron deficit that was left when light excited an electron in the chlorophyll
H2O -> 2H+ + 2e- + 1/2 O2
light reaction photosynthesis: light e-‘s
light excites electrons in chlorophyll and NADP+ -> NADPH
ATP is generated in
photophosphorylation
light reaction photosynthesis: H2O e-‘s
electrons from photolysis of H2O fill in electron hole in chlorophyll and H2O -> O2 + H+
calvin cycle: CO2 -> CH2O
via the enzyme rubisco
rubisco
- enzyme
- attaches RuBP and CO2 together; end up with a 6 Carbon Molecule
calvin cycle occurs where
stroma
how many turns does it take to make glucose
6?
why is stroma site of calvin cycle
it has the appropriate enzymes and a suitable pH for the calvin cycle
why are thylakoids the site of light reaction
it has ETC and ATP synthase for photophosphorylation
as electrons move down the ETC
they release energy, which will then be used to pump H+ from stroma to thylakoid space
photosystems
large complexes of proteins and pigments (light-absorbing molecules) that are optimized to harvest light; they play a key role in the light reactions
energy coupling
uses energy from exergonic pathway to power an endergonic pathway
reaction is not spontaneous so it is
endergonic
reaction is spontaneous so it is
exergonic
light reaction: light is captured by what
by the thylakoids (photosystems I and II)
photosystem I: electrons
electrons are excited
- NADP+ accepts electrons -> NADPH
- NADPH then goes to the stroma and is involved in the Calvin Cycle
cytochromes
proteins that act as electron acceptors
- each one is more electronegative
photosystem II: electrons
- electrons are excited
- electrons are passed down through the ETC
- during the transport of electrons, H+ ions are actively transported across the thylakoid membrane
- electrons are received by PS I and the process starts all over again
what happens when photosystem II is depleted of electrons
- it uses H2O to replenish electrons
- photolysis: H2O -> 2H+, 1/2 O2, 2e-
- this causes more H+ ions to accumulate in the thylakoids
where does photolysis occur?
thylakoid space/lumen
where do the products of photolysis go?
- H+ go towards ATP Synthase
- e- is used to replenish PS
oxygen from photolysis goes where?
released as a waste product
function of ATP synthase
the ATP synthase transports H+ ions out of the thylakoid membrane (across lipid bilayer) making ATP in the process
- chemiosmosis
- photophosphorylation
calvin cycle’s three steps
- fixation
- reduction
- regeneration
Calvin Cycle: starting carbons
- 15 Carbons
(3 RuBPs)
RuBP
- ribulose bisphosphate
- 5 Carbon molecule
Calvin Cycle: carbon fixation
- rubisco attaches a CO2 to each RuBP
- end up with three 6 Carbon molecules
- 3 CO2 were added
- this 6 Carbon molecule is unstable - breaks into 3 Carbon molecule
- result: 6x 3 Carbon Molecules
what is meant by phosphorylate
to add a phosphate group to a molecule
Calvin Cycle: reduction
- ATP from light reaction phosphorylates the 3 Carbon Molecule
- NADPH from light reaction reduces 3 Carbon Molecule
Calvin Cycle: what happens to the NADPH in reduction
- NADP+ goes back into the thylakoid
Calvin Cycle: departure of G3P
- 1 G3P (3 Carbon Molecule) will leave calvin cycle
Calvin Cycle: regeneration phase
- ATP is used to rearrange the remaining 15 carbon molecules back into 3 molecules of RuBP
how many turns of the Calvin Cycle to make glucose
6 turns
light reaction: where does photolysis occur
it occurs in the thylakoid membranes of chloroplasts
light reaction: where does photolysis occur
it occurs in the thylakoid membranes of chloroplasts
light reaction: what does the ATP synthase involve?
- involves H+ ions
- powered by the proton gradient
- flow of protons from thylakoid lumen into the stroma provides energy needed to convert ADP + Pi into ATP
is ADP reduced or oxidized?
no, it is simply converted into ATP
what are the 3C molecules called that result from the splitting of the unstable 6C molecules
3 PGA
- 3 Phosphoglycerate
how is 3PGA phosphorylated by ATP
- the ATP gives a P to 3PGA to help form G3P
how many times must the calvin cycle occur to produce a glucose molecule
- cycle must occur 6 times to produce one molecule of glucose
- each turn of the cycle fixes 1 molecule of CO2
how many times must the calvin cycle occur to produce a glucose molecule
- cycle must occur 6 times to produce one molecule of glucose
- each turn of the cycle fixes 1 molecule of CO2
how many times must the calvin cycle occur to produce a glucose molecule
- cycle must occur 6 times to produce one molecule of glucose
- each turn of the cycle fixes 1 molecule of CO2
where does cellular respiration take place in prokaryotes
- in cytoplasm
- on cell membrane
where does cellular respiration take place in eukaryotes
- begins in cytoplasm
- mitochondria
mitochondria: inner membrane
- location of the ETC
mitochondria: matrix
where kreb’s cycle happens (aka citric acid cycle)
what is the purpose of cellular respiration?
to make ATP
what happens when there is no oxygen for respiration?
anaerobic respiration
reduction in biology
- means the molecule has hydrogen with its electron attached to a carbon
oxidation in biology
- means the hydrogen and its electrons have been stripped from the carbon compound
what is cellular respiration
- a metabolic pathway that uses organic molecule to release potential energy
- we use electrons and H+ ions to make ATP
what are the steps of cellular respiration?
- glycolysis
- oxidation of pyruvate
- krebs cycle
- ETC
glycolysis location
cytoplasm/cytosol
krebs cycle / citric acid cycle location
happens in the mitochondria
electron transport chain location (resp.)
- inner membrane of mitochondria
electron carriers (respiration)
- NAD+ -> NADH
- FAD -> FADH2
NAD+ -> NADH
atp yield
makes 3x ATP each
FAD -> FADH2
makes 2x ATP each
glycolysis: step 1
2x ATP molecules phosphorylate glucose (invest energy)
glycolysis: step 2
an enzyme breaks the glucose plus 2 phosphates into two smaller molecules
- an inorganic phosphate found in cytoplasm binds to 3C
glycolysis: step 3
enzyme and NAD+ bind to 3 carbon molecules
- NAD+ will be reduced to NADH and the 3 C molecule will be phosphorylated
glycolysis: step 4
- enzymes will attach to the 3 carbon molecule and use a phosphate to phosphorylate ADP -> ATP (happens twice)
glycolysis: step 5
glucose is now pyruvate
glycolysis: ATP in
2 ATPs
glycolysis: ATP out
4 ATPs
glycolysis: NADH out
2 NADH
glycolysis: substrate level phosphorylation
- using enzymes to make ATP
-enzymes phosphorylates ADP
oxidation of pyruvate makes how many NADH
2X NADH
oxidation of pyruvate makes how many Acetyl COA
2X Acetyl COA
oxidation of pyruvate makes how many CO2
2X CO2
if pyruvate dehydrogenase doesn’t work, acetyl COA won’t be made, but pyruvate is still made
steps of oxidation of pyruvate
NEED AN ANSWER
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
what is the point of oxidation of glycolysis and the krebs cycle
to completely oxidize glucose to make ATP
- to make e- carriers to bring electrons to the ETC
how many ATPs are made by 1 molecule of glucose
36 ATP
how many ATP made in glycolysis
2 ATP
how many ATP made in oxidation of pyruvate
none
how many ATP made in krebs cycle
2 ATP
how many NADH made in glycolysis
2 NADH
how many NADH made in oxidation of pyruvate
2 NADH
how many NADH made in krebs cycle
6 NADH
how many FADH2 made in glycolysis
0
how many FADH2 made in oxidation of pyruvate
0
how many FADH2 made in krebs cycle
2 FADH2
electron transport chain in respiration: step1
electrons are passed from NADH to proteins in ETC (electrons carried are oxidized)
electron transport chain in respiration: step 2
the electrons are passed from one protein to another in a “chain” like fashion
electron transport chain in respiration: step 3
oxygen (very electronegative) pulls the electrons down the ETC
electron transport chain in respiration: step 4
when electron carriers get oxidized the H+ comes off
electron transport chain in respiration: step 5
the electrons being passed from one protein to another use some energy to pump the hydrogens into the inter membrane space
- NAD+ can now be reused
electron transport chain in respiration: step 6
H+ gradient builds up in inter membrane space
why cant H+ pass back into the matrix due to diffusion?
because H+ is charged therefore it cannot pass back into the matrix via diffusion
how did we establish this proton gradient (etc)
by NADH dropping of H+ and they get pumped into the inter membrane space
what role did the electron carriers play (resp etc)
they bring e- which are used as energy to pump the H+
- without e-, H+ cannot be actively transported to the IMS
what happens every time a hydrogen ion passes through the ATP synthase
every time an H+ ion passes through, the ATP synthase does a turn and phosphorylates ADP to turn it into ATP
electron transport chain in respiration: step 7
hydrogen ions want to move from high concentration to low. ATP synthase is an enzyme that allows the hydrogen ions to pass through. every time a hydrogen ion passes through the ATP does a turn and phosphorylates ADP into ATP
electron transport chain in respiration: step 8
H+ is attracted to negatively charged oxygen to form water
chemiosmosis (resp.)
making ATP using a charged ion gradient (H+)
oxidative phosphorylation
making ATP using O2 by phosphorylating ADP into ATP
how many ATP are made from NADH
3 ATP
how many ATP are made from FADH2
2 ATP
at the end of glycolysis what did we have
pyruvate
why do we need NAD+ in glycolysis
NAD+ will oxidize another molecule in glycolysis pathway to make energy (ATP)
lactic acid fermentation: step 1
NADH attaches to pyruvate
lactic acid fermentation: step 2
NADH gets converted to NAD+
lactic acid fermentation: step 3
pyruvate is turned into Lactic Acid
lactic acid fermentation: step 4
lactic acid is sent to the liver and converted back into pyruvate
alcohol fermentation: step 1
NADH attaches to pyruvate
alcohol fermentation: step 2
NADH gets converted to NAD+
alcohol fermentation: step 3
pyruvate is turned into ethanol and CO2
G3P full name
glyceraldehyde 3 phosphate
PGAL
other name for oxidation of pyruvate
Prep Reaction
where does energy go? is the energy released 100% efficient
No, some of the energy is lost as heat
- endotherms (humans use it up to heat ourselves)
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why does an ATP molecule have so much energy
3 phosphate groups are highly polar and repel each other, thus containing very high amounts of potential energy
- highly unstable bonds (means they’re high energy)
ATP-ADP Cycle: how is energy released to the cell
the breakdown of ATP releases energy for the cell
- the hydrolysis of ATP
cell respiration: why do we eat and breathe
the O2 that we inhale (inspire) keeps pulling electrons off the food we eat. this creates energy that is used to produce ATP
electron flow provides energy for
chemiosmotic synthesis of ATP
one sentence summary of photosynthesis
the light reaction produces the energy rich molecules ATP & NADPH which are used in the Calvin Cycle to reduce CO2 in C6H12O6
mitochondria intermembrane space: [H+]
High [H+]
NAD+ / NADH - importance!!
NAD+ grabs the electrons from food and becomes NADH which carries the electrons to the electron transport chain where oxygen ultimately grabs the electrons. This regenerates NAD+ so it can grab more electrons from food
krebs Cycle products
- the acetyl coA is completely reduced to CO2
- produces some ATP
- produces NADH and FADH2 that carry electrons to the ETC
how many times does Krebs cycle occur for each glucose
2 cycles
what happens as electrons move down the ETC
they release energy that will be used to pump H+ from the matrix to intermembrane space
final electron acceptor
O2
ATP Synthase
- in the inner membrane, makes ATP from ADP and Pi
- as the H+ comes form its concentration gradient through the channel protein in the inner mitochondrial membrane, the ATP synthase is activated an acts as rotor, putting a phosphate on ADP to turn it into ATP
why is it important that 100% of glucose is not used for energy?
what is not used for energy is released as heat which maintains the body temperature of organisms
endotherms
heated from the inside; heat generated during respiration
- high metabolic rate
what happens as electrons pass along the photosynthetic electron transport chain?
protons (H+) accumulate in the thylakoid space due to the oxidation (photolysis) of water and pumping of protons via ETC. these protons then pass through an enzyme called ATP Synthase, which uses the energy stored in the proton gradient to synthesize ATP
what could happen if rubisco had a mutation and it changed the way it folded in its tertiary structure
rubisco is an enzyme that catalyzes the fixation of carbon
what is the name of the metabolic pathway of glucose oxidation that occurs in the cytoplasm of the cell?
glycolysis
what is the name of the process that adds the third phosphate to an ADP molecule using an enzyme in the glycolysis metabolic pathway
substrate level phosphorylation
list one reason why the ETC may not be able to make ATP
- loss of proton gradient
- loss of O2
***NEED ANSWER
what is the one place in ETC (resp.) that is permeable to the reentry of hydrogen protons
ATP Synthase
where in the mitochondria will acetyl-coA be found
matrix
second law of thermodynamics
when energy is converted from one form to another, some energy is “lost”. “lost” means that some of the energy becomes unusable or unable to do work
unusable energy is usually in the form of
heat
which reactions can occur spontaneously
exergonic reactions, they can occur without an input of energy
phosphorylation is the process of
adding energy and a inorganic phosphate to ADP to make ATP
substrate level phosphorylation
occurs during glycolysis
when oxygen is available, most cells will generate ATP using aerobic respiration
- glycolysis
- krebs cycle
- oxidative phosphorylation
when oxygen is not available, cells will generate ATP by anaerobic respiration
- alcohol fermentation
- lactic acid fermentation
pyruvate AKA
pyruvic acid
glycolysis summary
glycolysis takes 1 molecule of glucose and turns it into 2 pyruvate, 2 NADH, and a net of 2 ATP
- occurs in the cytosol
oxidative phosphorylation
process of producing ATP from NADH and FADH2
- electrons from NADH and FADH2 pass along the ETC
- the chain consists of proteins that pass these electrons from one carrier protein to the next
- along each step of the chain, electrons give up energy used to phosphorylate ADP to ATP
mitochondrial intermembrane space
- narrow area between outer and inner membrane
- H+ ions accumulate here
chemiosmosis
the mechanism of ATP generation that occurs when energy is stored in the form of a proton concentration gradient across a membrane
pH of mitochondria
as H+ are transferred from the matrix to the intermembrane space, the concentration of H+ increases (pH decreases)
where does NADH -> NAD+ in ETC
PC I
where does FADH2 -> FAD in ETC
PC II
where does H+ + 1/2 O2 -> H2O in ETC
PC IV
what if oxygen is not present? (respiration)
if oxygen is not present, no electron acceptor exists to accept the electrons at the end of the ETC. if this occurs, NADH accumulates. after all the NAD+ has been converted to NADH, the Krebs Cycle and Glycolysis both stop (both require NAD+ to accept electrons). no ATP produced as a result
objective of both processes of anaerobic respiration
to replenish NAD+ so that glycolysis can proceed once again
- this occurs in the cytosol alongside glycolysis
explain the purpose of the two membranes of the mitochondria
- the two membranes create an intermembrane space that allows H+ ions to accumulate
- creates a proton gradient which drives the movement of protons through ATP synthase
where does oxidation of pyruvate occur
happens in the mitochondria
how many ATP does anaerobic respiration produce
2 ATP
