What is metabolism?
The sum of all chemical reactions that occur within an organism.
What is anabolism?
Building complex molecules, endergonic, biosynthetic
What is catabolism?
Breaking down complex molecules, degradative, exergonic
What is Oxidation?
- Loss of electrons,
- Gain of oxygen
- Loss of hydrogen
- C O bonds
- Lower potential energy
What is Reduction?
- Gain of electrons
- Loss of O
- Gain of H
- Higher potential energy
- C H bonds
Which nanometers is the light visible?
- 400-700 nm
- Blue and red are absorbed best, green is reflected
What is fixation?
Conversion of an inorganic molecule to an organic molecule
Limiting factors of photosynthesis
- Temperature: reverse U shape
- Co2 concentration: increase and stop
- Light intensity: increase and then stop
- Happens in cytoplasm after glycolysis if O is not present
- In yeast, ethanol and CO2
- In animals, lactic acid, interchangable reaction, turns back into pyruvate when O levels are back to normal
- Just 2 ATP
Explain Glycolysis general facts please.
- Happens in cytoplasm and does not require O or any organelles.
- Is the breakdown of glucose into two pyruvate molecules.
- Observed in prokaryotic and eukarytic cells.
- 2 ATP is used to start the process, 4 is produced.
Explain Glycolysis steps:
- 4 steps
- 1)Phosphorylation: Glucose is phosphorylated by 2 ATP, adding a phosphate group to the first and the sixth carbon. (the enzyme to fix the phosphate is inhibited by ATP, allosteric)
- 2)Lysis: The phosphorylated fructose is split into two G3P
- 3)Oxidation: The G3P are oxidized by 2 NADP to create 2 NADPH and the energy produced is used to add 2 more phosphate groups to the ends of the G3P
- 4)ATP Production: The phosphate groups are removed and transferred to 4 ADP to make 4 ATP
What are the end products of Glycolysis?
- 2 NADPH
- 2 ATP (net)
- 2 Pyruvate
What is the link reaction where does it occur general info please
Happens in the matrix of the mitochondria after the pyrivate are transferred there through active transport.
What are the steps of the Link reaction?
- The pyruvate are decarboxylated to create acetyl, the 2CO2 are released.
- NADP is reduced to NADPH, acetyl is oxidized
- CoA binds to acetyl to form 2 acetyl CoA
Connection between CoA and lipids?
CoA can be produced from fatty acids for storage purposes when energy is high.
What is the role of the cristae?
Increases surface area for oxidative phosphorylation
What is the role of the inter-membrane space?
A reservoir for H ions
What is the role of the inner membrane
Carriers for ETC and ATP synthase are there
What is the role of the outer membrane
Isolates the enzymes in the mitochondria and compartmentalizes.
What is the Krebs cycle?
- Cell respiration
- Happens after link reaction when ATP levels are low.
- Happens in the matrix of the cell
What are the steps of the Krebs cycle?
- Acetyl CoA is and oxaloacetate (4C) are bound together as the CoA is removed and recycled. Citrate (6C) is formed.
- The Citrate is decarbxylated and oxidized as NAD is reduced to NADH. CO2 is removed from each pyruvate
- The step is repeated. The molecule turns back into a 4C molecule.
- The 4C molecule is rearranged to oxaloacetate (4C) as one more NADP is reduced, FAD is reduced to FADH and ADP is phosphorylated (substrate level) to form ATP
- In the end, 6 NADH, 2 FADH2, 2 ATP, 4 CO2 is produced
How many ATP molecules has been produced up until Krebs cycle?
- 2 in glycolysis and 2 in Krebs cycle
- 2 CO2 released in link reaction, 4 in Krebs, 6 in total
Electron Transport chain general info
- Happens in matrix and inter-membrane space
- Gains the most ATP
- O used for the first time
- Oxidative phosphorylation
What are cytochromes?
- Embedded in membrane
- Proteins that transfer the electrons with a group called haem, found in all plants, animals and mitochondria, easily reduced and oxidized
What is coenzyme Q?
- Embedded in membrane
- Transports electrons
What is the source of electrons for the ETC?
NADH and FADH2 (3 ATP for NADH, 2 for FADH2)
Every time an electron is carried, a small amount of energy is released, which is used to turn ADP into ATP.
Electron transport chain?
- FADH2 and NADH are oxidized and the H ions are transported by cytochrome complexes and Coenzyme Q from the matrix to the intermembrane space using the energy released.
- The NAD and FAD are recycled in the Krebs cycle and link reaction and glycolysis
Chemiosmosis cell respiration general info
- End of electron transport chain
- 32 net gain ATP in cell respiration
- Chemiosmosis explain
- H ions pass through ATP synthase using passive transport, enzymes harness their energy to phosphorylate ADP to ATP
- The O accepts the remaining H ions and turns into H2O
Cell respiration general overview:
Glycolysis link reaction krebs cycle electron transport chain chemiosmosis
Photosynthesis general information
- Turns light energy into chemical energy
- Stored in sugars
- Occurs in autotrophs
- Anabolic process
- Light dependent, light independent
What are plastids?
- Organelles that all develop from proplastids photosynthetic eukaryotic cells
- 3 types
- Leucoplasts: energy storehouses
- Chromoplast: produce colors
- Chloroplasts: photosynthesis
P680, protein complex composed of pigments
P700, protein complex composed of pigments
Light dependent reaction place
Happens in the granum and the thylakoid membranes
Which pigments absorb light?
Chlorophyl a, chlorophyll b, carotenoids
Light dependent reaction everything
- Photosystem 2 absorbs photons until it reaches chlorophyll a, one of chlorophyll a electrons is excited and moves to a higher energy level
- 2) Excited electron is captured by primary acceptor
- Photon energy is used to split a water molecule in two, to replace the excited electron
- H is used to create gradient and to replace, O is released.
- 4)Electron transport chain
- Electron is moved to PQ, cytochrome complex (pumps H ions into thylakoid space using the energy lost in energy transport chain) and another electron carrier and then to the Photosystem 1. The gradient created is used by ATP synthase to produce ATP later on.
- The energy lost during the electron trnasport chain is used to drive chemiosmosis through the pumping of H ions into the thylakoid space, increasing the gradient and driving the passive transport of H ions from the ATP synthase to the stroma.
- 6) Photoactivation of Photosystem 1, the electron that has lost its energy replaces the excited chlorophyll a electron.
- 7) electron acceptor accepts the excited electron
- 8)electron carrier ferradoxin carries the electron to reduce NADP to NADPH
What are the end products of the light dependent reaction?
- 2 NADPH and 2 ATP to be used in the light independent reaction
- Also O is produced
What is cyclic phosphorylation?
The electron is transferred back to the cytochrome complex from the ferradoxin, no NADPH is produced but ATP and O is produced.
Light independent reaction general info?
- Happens in stroma
- Production of carbohydrates
- Calvin cycle
- NADPH is used insted of photon for energy
- 6 CO2 is taken from the air
Light independent reaction steps
- 1)CO2 is fixed to 5 carbon compound RuBP using Rubisco
- 2)the highly unstable 6 carbon compound splits into glycerate-3 phosphate
- 3)NADPH is oxidized to NADP, G3P is reduced, ATP turns into ADP to add phosphate group to G3P, turning it into triose phosphate
- 4)10 of 12 triose phosphate is turned into RuBP for recycling, 2 bind to turn into sugar phosphate
Compare light dependent and indpeendent
- Water usage
- Energy used (ATP and NADPH, Photon)
What does the extensive surface area of thylakoids mean for a cloroplast?
Larger surface area for light absorbtion
What does the small space within the thylakoids mean?
Allow for faster accumulation of protons for concentration gradient
What does the stroma region being similar to the cytosol of the cell mean?
Diffusion of products, enzymes present
What does the double membrane on the outside mean for a chloroplast?
Isolates the working parts of the enzymes, keeps it in optimal condition, controls concentration
What are palisade cells?
Close to the top of the leaves with high density of chloroplasts
Thylakoid membrane and the inner membrane of mitochondria are similar!
ETC and chemiosmosis
Stached membranes of chloroplast and cristae are similar
Higher surface area
Low volume of intermembrane spaces
Faster reach to concentration proton gradient for chemiosmosis
Stroma and matrix
Enzymes for reactions, diffusions of molecules
Compare respiration chemiosmosis and photosynthesis chemiosmosis
- 1)Moved from matrix to inter membrane space, moved from thylakoid space to stroma
- 2)Chain embedded in the inner membrane (cristae, chain embedded in the thylakoid membrane
- 3) energy used to pump electrons into inter membrane space, energy used to pump electrons into stroma
- 4)hydrogen ions come from the matrix, hydrogen ions come from the thylakoid space
- 5)hydrogen ions diffuse back into the matrix through ATP synthase, hydrogen ions diffuse back into the thylakoid space through the ATP synthase
- SUMMARY: ATP synthase is same, places are different