Use Ch. 9-10 in \"Campbell Biology\" Pearson book by Urry, Cain, Wasserman, Mino
ID: 270991 • Letter: U
Question
Use Ch. 9-10 in "Campbell Biology" Pearson book by Urry, Cain, Wasserman, Minorsky, and Reece. Write in multiple paragraph form. Please be detailed. Include vocabulary listed below question.
5) Compare and contrast eukaryotic photosynthesis and respiration, with respect to their detailed mechanisms and their outcomes. Mention the key kinds of molecules that participate in both processes. Why are the processes similar, and why are they different? (Hint: first focus on the structural, functional, and evolutionary similarities. For the differences, focus on things that are connected to the homologous structures.)
Important Concepts
Respiration (Chapter 9)
The Hindenberg analogy: what is a redox process, and what makes it exergonic?
Glycolysis:
Where does it happen (in eukaryotes and prokaryotes)?
What is the energy investment phase? Why is it important?
When glucose (or its product) gets oxidized, what is the oxidizer? What gets reduced?
ATP made by substrate-level phosphorylation
Pyruvate
Kinases
Isomerases
Dehydrogenase & oxidation
Phosphofructokinase is allosterically regulated as part of a feedback inhibition system
Why is glycolysis considered to be an ancient pathway?
Mitochondrial transport proteins:
Porins
Pyruvate/OH- exchanger
ATP/ADP translocase (exchanger)
Phosphate/OH- exchanger
Electron shuttles (the book shows 2, but in the lecture I showed a detailed diagram of the FADH2 shuttle only.
Before the citric acid cycle:
COO- becomes CO2
Acetyl CoA and the CoA cycle
Citric acid (Krebs) cycle:
Where does it happen (in eukaryotes and prokaryotes)?
Acetyl in, CO2 out
Why it’s a cycle
NADH, FADH2, ATP produced
Why does the citric acid cycle stop if no O2 is present?
Complex II is attached to the membrane; compare this to the book’s citric acid cycle diagram. Why does this matter?
Electron transport chain & ATP synthase:
Electrochemical proton gradient. It's also a pH gradient.
Where electrons come from & where they go.
What is the energy source for making the proton gradient? Where do the protons come from?
NADH & FADH2, as oxidizers and as reducers. For each redox step in respiration, what gets oxidized & what gets reduced? What’s more electronegative?
Why is O2 needed? Could there ever be an electron transport chain without O2?
Structure of mitochondrion: inner & outer membranes, intermembrane space, matrix
How ATP synthase works
Why 1 NADH is worth more than 1 FADH2
Why 1 NADH is worth more than 1 ATP
Why is ATP better for energy transfers, while glucose is better for energy storage?
Metabolic poisons (drugs that alter ETC/proton gradient). Imagine a drug that blocks the normal function of one of the proteins or of the inner mitochondrial membrane itself. How would the drug affect other parts of cellular respiration such as O2 consumption, NAD+ and NADH levels, rates of glycolysis and citric acid cycle, etc.?
Respiration: how foods other than glucose are used
How other metabolic pathways (including autophagy and anabolic pathways) relate to respiration
Feedback inhibition in regulating respiration. How is the rate of ATP production controlled?
Evolution of proton gradients, e- transport chains, & respiration:
How do prokaryotes do respiration?
What advantage do prokarytes have in respiration?
ATP synthase is also an ATPase. Why? How is this connected to the evolution of cellular respiration?
Uses of proton gradient aside from making ATP.
Uncoupling proteins
UCP1 & brown fat. How is the heat generated?
UCP2 & superoxide. How & where is superoxide formed? Why do reactive oxygen species (ROS) matter?
How does UCP2 help prevent ROS formation?
What is bad about ROS? How can increasing ROS formation extend lifespan in nematodes?
Compare & contrast UCP 1 & 2. What causes each of these channels to open?
How do uncoupling proteins affect metabolic rate, O2 use, NAD+/NADH, etc.? How is UCP1 similar to dinitrophenol (DNP)? How is it different?
Cancer cells: cellular respiration and fermentation
Why would cancer cells preferentially use fermentation over cellular respiration? Why is there a tradeoff between biosynthesis and ATP generation?
What is ectopic ATP synthase? “Combination therapy targeting ATP synthase and 26S proteasome induces ER stress in breast cancer cells.” What does this mean? Why would it work?
Fermentation (Ch. 9):
Why respiration needs O2
Why is glycolysis possible without O2, but not the citric acid cycle or ETC?
Why does fermentation happen in your muscles?
Regenerating NAD+. Why is this important?
Eliminating pyruvate: how is it achieved in fermentation and in respiration, and why is it important?
Photosynthesis (Ch. 10):
How did photosynthesis change the earth? How is this related to the origin of eukaryotes?
Chloroplast structure: inner & outer membranes, thylakoids, stroma
Chlorophyll absorbs light energy… why isn’t this energy released as fluorescence?
Light reactions:
Photosystem structure & function
Resonance transfer vs. electron transfer in photosystem. Why is it important that the chlorophylls are grouped together in a big ring?
Splitting water: a redox reaction. Exergonic or endergonic?
Electron transport chain & ATP production. Does photosynthesis produce a net gain of ATP?
Noncyclic vs. cyclic e- flow. Where do the e- come from in each case? Why does each exist? What makes the chloroplast switch from one to the other?
Inputs & outputs of light rxns. What do the outputs get used for?
Why would ROS formation occur in the light reactions? How do chloroplasts limit ROS formation?
Calvin cycle:
Inputs & outputs. What outputs from the Calvin cycle become inputs in the light reactions?
What gets oxidized, what gets reduced
Rubisco. What is a carboxylase?
Compare & contrast photosynthesis vs. respiration, including a detailed comparison of electron transport chains. Why are they so similar?
Photorespiration:
Why it occurs
How is photorespiration detrimental to plant growth? How could it be beneficial to plants?
How does photorespiration affect the thylakoid proton gradient? What happens to the products of the light reactions?
C4 pathway. C4 does two things to prevent photorespiration.
CAM. Why is it used in succulent plants?
Rubisco vs. PEP carboxylase
Why don’t all plants use CAM or C4?
Explanation / Answer
The Hindenberg analogy: what is a redox process, and what makes it exergonic?
redox process is oxidation reduction process in which one substance gets oxidised and another gets reduced. As in the combustion of methane or gasoline, the fuel (glucose) is oxidized and oxygen is reduced. The electrons lose potential energy along the way, and energy is released, hence exergonic. Why Hindenburg analogy, in 1937 a german airship named Hindenberg made of alumina met with an accident and exploded, in which aluminium oxidised and oxygen reduced.
Glycolysis:
Where does it happen (in eukaryotes and prokaryotes)?: in both organisms happens in cytoplasm, in prokaryotes cytoplasm called as cytosol.
What is the energy investment phase? Why is it important? energy investment phase is, during glycolysis glucose is phosphorylated to be acted upon by enzymes and further converted to fructose bisphosphate, these two process requires ATP hence 2 ATP are consumed this intial phase of glycolysis is energy investment step. Its important because without phosphorylation enzymes cannot oxidise glucose to produce ATP, here potential energy of the glucose will be increased so that it can be easily oxidised to produce energy.
When glucose (or its product) gets oxidized, what is the oxidizer? What gets reduced?: Oxygen is the oxidizer and hence oxygen gets reduced
ATP made by substrate-level phosphorylation: with respect to glycolysis in two places a phosphate group is transferred from bisphosphoglycerate to ADP to form 2ATP, phosphoenol pyruvate to ADP to form 2ATP is called substrate-level phosphorylation.
Pyruvate: when 6 carbon glucose is split two molecules of 3 carbon pyruvate is formed, it is further metabolised to produce more energy either aerobically or anaerobically
Kinases: a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the substrate gains a phosphate group and the high-energy ATP molecule donates a phosphate group. In glycolysis Hexokinase, hosphofructokinase, Phosphoglycerokinase, Pyruvate kinase are involved.
Isomerases
Dehydrogenase & oxidation: Dehydrogenase are enzymes involved in transfering/removing hydrogen ion to form NAD to NADH. Triose Phosphate dehydrogenase enzyme removes hydrogen from Glyceraldehyde 3-phosphate or Dihydroxyacetone
Phosphate and transfers the hydrogen to NAD to produce NADH.
Phosphofructokinase is allosterically regulated as part of a feedback inhibition system: It is Phosphofructokinase allosterically regulated enzyme and is stimulated by AMP (derived from ADP) but is inhibited by ATP and by citrate. This feedback regulation adjusts the rate of respiration as the cell’s catabolic and anabolic demands change.
Why is glycolysis considered to be an ancient pathway?: because it does not require oxygen to produce ATP it is the first energy forming pathway in first formed ancient anaerobic organisms, still ita a pathway of choice in most of the obligate anaerobes.
Mitochondrial transport proteins:
Porins: are beta barrel proteins that cross a cellular membrane and act as a pore, throughwhich molecules can diffuse. Unlike other membrane transport proteins, porins are large enough to allow passive diffusion, i.e., they act as channels that are specific to different types of molecules. They are present in the outer membrane of gram-negative bacteria and some gram-positive bacteria of the group Mycolata (mycolic acid-containing actinomycetes), the mitochondria, and the chloroplast.
Pyruvate/OH- exchanger: named PyT transports pyruvate in to mitochondrial matrix using the proton gradient across the inner membrane.
ATP/ADP translocase (exchanger) named ANT in combination with Pi-OH exchanger facilitate interchange between cytosolic ADP and Pi and intramitochondrial ATP. ATP/ADP translocase (exchanger) is important in rate of respiration of mitochondria.
Phosphate/OH- exchanger named Pi-OH...see above answer
Electron shuttles (the book shows 2, but in the lecture I showed a detailed diagram of the FADH2 shuttle only. The mitochondrial inner membrane is impermeable to NADH, so NADH in the cytosol is segregated from the machinery of oxidative phosphorylation. The 2 electrons of NADH captured in glycolysis must be conveyed into the mitochondrion by one of several electron shuttle systems. Depending on the kind of shuttle in a particular cell type, the electrons are passed either to NAD+ or to FAD in the mitochondrial matrix (see Figure 9.16). If the electrons are passed to FAD, as in brain cells, only about 1.5 ATP can result from each NADH that was originally generated in the cytosol. If the electrons are passed to mitochondrial NAD+, as in liver cells and heart cells, the yield is about 2.5 ATP per NADH. The citric acid cycle also supplies electrons to the electron transport chain via FADH2, but since its electrons enter later in the chain, each molecule of this electron carrier is responsible for transport of only enough H+ for the synthesis of 1.5 ATP.
Before the citric acid cycle:
COO- becomes CO2: The release of six molecules of CO2 represents the complete oxidation of glucose. During the processing of two pyruvates to acetyl CoA, the fully oxidized carboxyl groups (¬COO-) are given off as 2 CO2.
Acetyl CoA and the CoA cycle: coenzyme A (CoA), a sulfur-containing compound derived from a B vitamin, is attached via its sulfur atom to the acetate, forming acetyl CoA, which has a high potential energy; in other words, the reaction of acetyl CoA to yield lower-energy products is highly exergonic. This
molecule will now feed its acetyl group into the citric acid cycle for further oxidation.
Citric acid (Krebs) cycle:
Where does it happen (in eukaryotes and prokaryotes)?: in eukaryotes: Mitochondrial matrix and prokaryotes: In the plasma membrane
Acetyl in, CO2 out, pyruvate enters mitochondria and converted in to or oxidised to Acetyl CoA which is further oxidised to several low energy molecules and CO2 is released to produce ATP
Why it’s a cycle: Acetyl CoA (from oxidation of pyruvate) adds its two-carbon acetyl group to oxaloacetate,
producing citrate. Again oxaloacetate is regenerated from malate. Oxaloacetate is ready to combine with acetyl CoA to produce citrate, hence it is cycle.
NADH, FADH2, ATP produced, : 3NADH, 1FADH2 and 2ATP are formed
Why does the citric acid cycle stop if no O2 is present?: The reducing power FADH2 and NADH2 passed through electron transport chain and the final electron acceptor is O2, to produce water, if there is no electron acceptor citric acid cycle stops because of feedback inhibition.
Complex II is attached to the membrane; compare this to the book’s citric acid cycle diagram. Why does this matter?
Electron transport chain & ATP synthase:
Electrochemical proton gradient. It's also a pH gradient. The exergonic “fall” of electrons to a lower energy level provides energy for the synthesis of ATP. As electrons pass through the cytochrome complex, H+ are pumped into the thylakoid space, contributing to the proton gradient that is subsequently used in chemiosmosis.
Where electrons come from & where they go. Electrons come from FADH2 and NADH2 and flow to H+
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