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Explore the intricate dance of cellular respiration and photosynthesis, from the sun's rays to generating ATP. Delve into key processes, like the Calvin cycle and light-independent reactions, explaining how CO2 is fixed into glucose. Uncover the magic of absorption pigments and photosystems in generating energy. Understand the importance of redox reactions and how ATP powers cellular functions. Discover adaptations in C4 and CAM plants for optimal photosynthesis. Learn about the vital role of terminal phosphates and nuclear fusion in generating energy. Grasp the significance of the breakdown of ATP coupled with endergonic reactions. Dive into the world of glycolysis and Krebs cycle to unravel the essence of energy production. Join in on this enlightening journey through the world of energy production in living organisms.
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I’ve Got the Power!! http://www.johnkyrk.com/glycolysis.html
Photosynthesis Let the sun shine….. Hooray for photosynthesis!!!!
The equations… • Cellular respiration-highly exergonic • C6H12O6 + O2 CO2 + H2O + ATP!! • Energy released thru oxidation of glucose • Photosynthesis-highly endergonic • Light + CO2 C6H12O6 + O2 • Light energy used to reduce CO2
Stroma • ATP produced in stroma • Calvin cycle • Thylakoid membrane • Photosystems embedded • ETCs • ATP synthase • Thylakoid space • H+ conc. gradient
Overview Produce energy Required for dark reactions “fix” CO2 into glucose Highly endergonic
Light independent reactions • Occur in thylakoid space & membrane • Light strikes chlorophyll • E- are boosted to higher energy level & travel down an ETC • Released energy captured to form ATP & NAPH • Water molecules borken apart to replace lost e- • Light independent reactions-carbon fixing • Uses energy captured in ATP & NADPH to reduce CO2 to sugar • Occurs in stroma
Absorption pigments • Light energy must be absorbed to be of any benefit • Pigments absorb certain wavelengths of light, which causes altered structure • Chloroplasts contain several pigments • Chlrophyll-absorbs violet, blue, red • Carotenoids-absorb blue & green • Phycocyanins-absorb green
What happens when chlorophyll absirbs light? • An e- becomes energized & moves to higher orbital • This is unstable-e- will normally release energy & move back to its original orbital • In photosynthesis, e- is captured by ETC
What is a photosystem? • Located in thylakoid membrane • Composed of a reaction center(chlorophyll), ,accessory(antennae) pigments, & an ETC • PSI- • evolved 1st, • cotains a dimer of chlorophyll, • can operate independently of PSII, • its ETC makes NADPH • PSII • Supllies e- to PSI • ETC produces ATP (photophosphorylation) • Accessory pigments absorb light & pass it chlorophyll • Only chlorophyll loses e- to ETCs
Light causes e- to become energized in PSII Jump to higher level
E- captured by cytochromes in ETC Energy used to push H+ from stroma to space Gradient used to produce ATP in stroma
E- end up in PSI, which has also lost e- To its ETC
PSI ETC gives its e- to NAD-an e- shuttle, it carries e- to calvin cycle
Cyclic e- flow-used when no NADP is available-(calvin cycle uses ATP faster than NADPH) This ETC shuts down No NADPH or O2
RuBP carboxylase CO2 is reduced RuBP is regenerated Reverse reactions of glycolysis Totals-1 glucose molecule Requires: 6CO2 18 ATP 12 NADPH How many ATP do we get From 1 glucose in cell resp? G3P In stroma
C4 plants • During hot weather, stoma close to avoid water loss • Causes build up of O2 which favors photorespiration-rubisco not selective • This inhibits calvin cycle • C4 plants have 2 adaptations to combat this • Bundle sheath cells in leaf interior-less PSII, so less O2 produced • PEP carboxylase-high affinity for CO2 despite O2 levls • Result is maintenance of high level of CO2, with a lower level of O2
CAM plants • Crusculacean Acid Metabolism • Open stomata at night-store CO2 as CA • During day, stomata closed-convert CA back to CO2 & photosynthesize
Terminal phosphates Break off fairly easily Due to instability of Molecule-provide Enough energy for most Cellular reactions
Coupled reactions-energy released from exergonic reactions drives endergonic reactions Nuclear fusion H Light energy He + EXERGONIC + O2 CO2 + H2O ENDERGONIC
This reaction is endergonic Sometimes the breakdown Of ATP is coupled to An endergonic reaction This compound is Phosphorylated & Has energy This bond is Broken & the Energy released Drives the reaction
ATP is formed through the oxidation (breakdown) of glucose in a series of step wise reactions
Redox (oxidation-reduction) Reactions • e- pass from one atom/molecule to another • H+ may also be lost or gained as a result • Molecule which loses the e- (H+) is oxidized • Molecule which gains e- (H+) is reduced • Must always occur together • The transfer of an e- to a more electronegative atom releases energy Na + Cl Na+ Cl- Na is oxidized Cl is reduced
6CO2 + 6H2O • During cellular respiration….. • Glucose is oxidized, oxygen is reduced • e- shift from glucose to highly electronegative O2 • Energy released a little at a time C6H12O6 + 6O2
No matter what food is taken in It can be fed into this process At some point!
So what’s really important aboutglycolysis? • Takes place in cytoplasm • With or without oxygen • Every living thing on the planet does it • Starts with 6C glucose • Ends with 2, 3C pyruvates • Gross 4 ATP • Net 2ATP, & 2 NADH
Nicotinamide adenine diphosphate, aka NAD, is an electron shuttle
So what happens next?That depends on whether or not O2 is present!!! • W/ O2, Kreb’s cycle & ETC • W/O O2, fermentation
Fermentation Hooray for Fermentation! • In the presence of O2, NADH carries its e- to the ETC • NAD is regenerated for use during glycolysis • W/o this regeneration, glycolysis would stop!! • If no O2 is present, fermentation regenerates NAD, & keeps glycolysis active
Used by anaerobic microorganisms (bacteria, yeast), & to make human foods
Used by human muscles during vigorous exercise (oxygen debt) • Allows muscles to continue working w/o oxygen • Build-up forces muscles to slow down until intake of O2 catches up • Lactic acid eventually breaks down
Outer membrane permeable to most small molecules • Inner membrane only permeable to ATP & pyruvate • Matrix-enzymes, water, Pi-parts of Kreb’s & ETC • Cristae-kreb cycle enzymes, ATP synthetase, ETC embedded in folds
Intermediate Step-what’s important…link between glycolysis & Kreb’smoves pyruvate into mitochondria (sometimes ACTIVE transport)happens twice per glucose (2 pyruvate)start w/ 2 pyruvateend with 2 acetyl CoAnet 2 NADH, 2 CO2 (by-product) To Krebs cycle oxidized
Series of redox Reactions which Completely finishes The oxidation of glucose
So Dunbar, help us out here! What’s important? • Each glucose requires 2 turns of cycle (2 pyruvates) • Takes place in matrix & cristae • Oxaloacetate is regenerated • Start w/ 2 acetyl CoA • End w/ oxaloacetate • Net, per glucose • 2 ATP • 6 NADH • 2 FADH2 (another e- shuttle) • 4 CO2 (by-product) • TOTALS SO FAR • 4 ATP • 10 NADH • 2 FADH2 • 6 CO2