chapter 9-10: bioenergetics and cellular respiration Flashcards
inputs of glycolysis
glucose, 2 NAD+, 2 ATP, 4 ADP + 4 Pi
outputs of glycolysis
2 pyruvate, 2 NADH, 4 ATP (2 net ATP)
formation of ATP during glycolysis is called…
substrate level phosphorylation
substrate level phosphorylation
an enzyme directly transfers a phosphate group from another substrate to ADP
how is glycolysis regulated?
excess ATP
where does glycolysis occur
cytosol; all life can perform glycolysis; does not require oxygen
pyruvate oxidation + processing
- eukaryotes with mitochondria take the products of glycolysis from the cytosol and bring it into the mitochondria
- pyruvate is shuttled from cytosol to mitochondrial matrix
- pyruvate is oxidized + processed into acetyl coA
- NAD+ is reduced
- first molecule of CO2 is formed
what must be established to power ATP synthase?
H+ gradient
oxidative phosphorylation (what is it)
production of ATP molecules by ATP synthase using the proton gradient established by redox reactions of the central electron transport chain; we get much more ATP this way
what do the products of glycolysis power
citric acid cycle
to power the ATP synthase enzyme what does there need to be
high concentration of H+ ions in the intermembrane space; these ions come from citric acid cycle; high concentration comes from ETC via redox reaction and active transport
where do carbons in the citric acid cycle go
they become carbon dioxide gas
what is happening in the citric acid cycle
a 6 carbon molecule is catabolized into a 3 carbon molecule; ATP made by substrate level phosphorylation
main purpose of citric acid cycle
NAD+ and FAD2+ are reduced to NADH and FADH2
what carries hydrogen atoms from citric acid cycle to ETC
NADH and FADH2
electron transport chain
purpose: create a pool of H+ ions in intermembrane space of mitochondria
how: uses energy from an electron to carry out active transport of H+ against the concentration gradient
ATP synthase
pool of H+ ions between mitochondrial membranes flow through the ATP synthase enzyme and spin it like a turbine - mechanical energy is transferred to ATP
aerobic respiration of glucose is___ (ender or exergonic)
exergonic
anaerobic respiration
mitochondrial metabolism is blocked due to no oxygen - smaller amounts of ATP made in cytosol during glycolysis + fermentation
what type of fermentation occurs in humans
lactic acid
what type of fermentation occurs in yeast
alcoholic
glycolysis and cellular respiration (O2 present)
glycolysis, pyruvate, pyruvate oxidation, citric acid cycle, ETC / ATP synthesis, CO2 and H2O
glycolysis and fermentation
glycolysis, pyruvate, fermentation, lactate or alcohol
3 metabolic pathways involved in harvesting energy of glucose to make ATP
- glycolysis - generates little ATP
- respiration (aerobic) - generates many ATP - 32 ATP per glucose
- fermentation (anaerobic) - 2 ATP per glucose
chloroplasts
- descendant from cyanobacterium (a photosynthesizing prokaryote) - endosymbiosis
- triple membrane
- thylakoids are a series of internal membrane systems and the site of photosynthesis
photosynthesis
- endergonic, anabolic
- sunlight provides energy
- CO2 reduced to form glucose
- H2O oxidized to form O2
- certain wavelengths of light drive photosynthesis
2 parts of photosynthesis
- light dependent reactions - collect light energy, oxidize H2O, store energy as ATP and NADPH
- light independent reactions - use ATP and NADPH to reduce CO2 and produce carbohydrates
what wavelengths of light are most effective at triggering photosynthesis
violet-blue and red
what are the light reactions
photosystem 1 and 2 (2 comes first)
photosystem 2
- photon energy of light is captured (electrons excited) and passed to a chlorophyll a; changes resonance of molecule
- loses an excited electron; electron hole is created
- water is split, causing:
-release of O2, accumulation of H+ in thylakoid lumen which runs ATP synthase
3 possible outcomes when an electron is excited
fluorescence / heat, resonance energy transfer, reduction / oxidation
resonance energy transfer + redox in photosystem 2
- pigments absorb photon
- energy transferred to reaction center giving an electron in pheophytin
- electron relaxes back to ground state through redox reactions in an ETC
ATP synthase in thylakoid membrane
- ETC actively transports H+ to thylakoid lumen
- creates a high concentration of H+ that flows through ATP synthase to make ATP
photosystem 1
- reduces NADP+
- cyclic electron flow
cyclic electron flow
- excited electrons are transferred back to ETC to generate ATP instead of reducing NADP; produces extra ATP to meet the energy needs of the Calvin cycle
light independent reactions
- CO2 fixation and the Calvin cycle
- takes place in the stroma
- CO2 reduced to carbohydrates
- enzymes in stoma use energy in ATP and NADPH to reduce CO2
rubisco
- earths most prevalent enzyme
- makes sugar from CO2 gas
- 8 active sites
the calvin cycle
CO2 goes in and a carbohydrate comes out, ATP used rather than generated
1. fixing carbon by RuBisCo
2. reducing 3-phosphoglutarate (3PGA)
3. regenerating ribulose 1, 5-bisphosphate (RuBP)
the different fates of G3P
- regenerates RuBP
- directly fuel glycolysis at the energy payout phase
- converted and exported to the cytoplasm to make glucose
- polymerized into starch molecules and stored in chloroplasts
problem with rubisco
cannot distinguish between CO2 and O2 - if binds to O2, leads to carbon loss called photorespiration
C4 plants
- fix carbon to a 4 carbon molecule
- 3 carbon compound + CO2
- PEP carboxylase
C3 plants
- RuBP + CO2 -> 2 3-carbon organic acids
- rubisco
strategies for photosynthesis
C4 plants: carbon fixing and calvin cycle occur in different cell types; spatial separation
CAM plants: carbon fixing and calvin cycle occur at different times of day; temporal separation (CO2 stored at night and used during the day)
photosynthesis has led to…
- formation of ozone layer
- colonization of land
- successful ATP formation by oxidative phosphorylation
