The document discusses key concepts in metabolism including:
- Metabolism extracts energy from fuels like carbohydrates and fats through catabolism and uses this energy to synthesize complex molecules through anabolism.
- Coupled reactions allow thermodynamically unfavorable reactions to proceed by making the overall free energy change negative.
- ATP is the universal energy currency in biological systems, and its hydrolysis drives metabolism by shifting reaction equilibria.
The document discusses different carbon fixation pathways in plants. C4 plants fix carbon dioxide in mesophyll cells before it is transported to bundle sheath cells, concentrating CO2 around Rubisco and reducing photorespiration. This allows higher photosynthesis rates with lower transpiration. C4 plants evolved in hot, dry climates. Crassulacean acid metabolism (CAM) plants fix CO2 at night and store it as malate, releasing CO2 for photosynthesis during the day, reducing water loss. CAM metabolism is inducible and some plants like ice plant switch to CAM in response to salt or drought stress.
The document discusses photosynthesis in C3 and C4 plants. It shows that willow and maize plants will both survive under a sealed cover individually, but only the willow survives when the two are combined, due to the maize plant using oxygen during photosynthesis. It then examines the differences in carbon fixation pathways between C3 and C4 plants, including their A-Ci curves and leaf anatomy, showing C4 plants have adaptations that allow them to more efficiently fix carbon in hot, dry environments. The document depicts the pathways that allow C4 plants like maize to concentrate CO2 around rubisco through compartmentalization between mesophyll and bundle sheath cells.
The rate of photosynthesis is often lower than expected for several reasons: 1) Dark respiration occurs during the day which reduces net photosynthesis, 2) Not all wavelengths of light are absorbed efficiently by leaves, and 3) Factors like photorespiration and suboptimal conditions can limit carbon fixation and respire photosynthates. Leaf anatomy, physiology, and environmental conditions can prevent photosynthesis from reaching its maximum potential.
- The document discusses plant reproduction and alternation of generations between haploid gametophytes and diploid sporophytes in different plant groups like mosses, ferns, gymnosperms and angiosperms.
- It describes how mosses have dominant gametophytes that produce sporophytes which bear spores and how ferns and seed plants have dominant sporophytes.
- It also summarizes the ABC model of flower development in which different combinations of transcription factors determine the identity of floral organs.
The document discusses plant growth and how it can be calculated and expressed. It explains that plant growth rate (RGR) depends on factors like species and development stage. RGR can be broken down into components like net assimilation rate (LAR), specific leaf area (SLA), and leaf mass fraction (LMF). These components, along with daily photosynthesis rate (PS A) and carbon concentration, determine how quickly a plant grows. Variation in growth rates between species is often due to differences in LAR components like SLA. Faster growing plants generally have higher LAR values.
The document discusses key concepts in metabolism including:
- Metabolism extracts energy from fuels like carbohydrates and fats through catabolism and uses this energy to synthesize complex molecules through anabolism.
- Coupled reactions allow thermodynamically unfavorable reactions to proceed by making the overall free energy change negative.
- ATP is the universal energy currency in biological systems, and its hydrolysis drives metabolism by shifting reaction equilibria.
The document discusses different carbon fixation pathways in plants. C4 plants fix carbon dioxide in mesophyll cells before it is transported to bundle sheath cells, concentrating CO2 around Rubisco and reducing photorespiration. This allows higher photosynthesis rates with lower transpiration. C4 plants evolved in hot, dry climates. Crassulacean acid metabolism (CAM) plants fix CO2 at night and store it as malate, releasing CO2 for photosynthesis during the day, reducing water loss. CAM metabolism is inducible and some plants like ice plant switch to CAM in response to salt or drought stress.
The document discusses photosynthesis in C3 and C4 plants. It shows that willow and maize plants will both survive under a sealed cover individually, but only the willow survives when the two are combined, due to the maize plant using oxygen during photosynthesis. It then examines the differences in carbon fixation pathways between C3 and C4 plants, including their A-Ci curves and leaf anatomy, showing C4 plants have adaptations that allow them to more efficiently fix carbon in hot, dry environments. The document depicts the pathways that allow C4 plants like maize to concentrate CO2 around rubisco through compartmentalization between mesophyll and bundle sheath cells.
The rate of photosynthesis is often lower than expected for several reasons: 1) Dark respiration occurs during the day which reduces net photosynthesis, 2) Not all wavelengths of light are absorbed efficiently by leaves, and 3) Factors like photorespiration and suboptimal conditions can limit carbon fixation and respire photosynthates. Leaf anatomy, physiology, and environmental conditions can prevent photosynthesis from reaching its maximum potential.
- The document discusses plant reproduction and alternation of generations between haploid gametophytes and diploid sporophytes in different plant groups like mosses, ferns, gymnosperms and angiosperms.
- It describes how mosses have dominant gametophytes that produce sporophytes which bear spores and how ferns and seed plants have dominant sporophytes.
- It also summarizes the ABC model of flower development in which different combinations of transcription factors determine the identity of floral organs.
The document discusses plant growth and how it can be calculated and expressed. It explains that plant growth rate (RGR) depends on factors like species and development stage. RGR can be broken down into components like net assimilation rate (LAR), specific leaf area (SLA), and leaf mass fraction (LMF). These components, along with daily photosynthesis rate (PS A) and carbon concentration, determine how quickly a plant grows. Variation in growth rates between species is often due to differences in LAR components like SLA. Faster growing plants generally have higher LAR values.
7. Allosterische enzymen volgen niet de Michaelis Menten-kinetiek Grafiek van productvorming tegen substraatconcentratie geeft een S-curve (hemoglobinecoöperativiteit). Wat is de betekenis van de S-curve bij allosterische enzymen?
8. ATCase bestaat uit verschillende subeenheden: Regulator en katalytische subeenheden Modificatie van cysteïneresiduen. Enzym valt uiteen in subeenheden.
13. Actieve site van ATCase Opheldering structuur met X-Ray. Pala bindt op de grens tussen paren van c-ketens binnen de katalytische site. Ieder katalytisch trimeer bevat drie actieve sites voor het enzym.
35. pseudosubstrate R R R R C C C C Pseudosubstraat remming cAMP bindt coöperatief: een cAMP maakt binding van tweede cAMP veel makkelijker Competitie tussen cAMP en C-subunits voor binding aan R-subunit: evenwicht cAMP activeert eiwitkinase A (PKA)
36. R-keten bevat de sequence (Arg-Arg-Gly-Ala-Ile. Hetgeen lijkt op de consensussequentie (behalve Ala voor serine). Deze pseudosignaalsequentie van R bezet de katalytische site van C.
37. PKA fosforyleert een groot aantal eiwitten en reguleert een groot aantal processen b.v. adrenaline effecten opname van water in de nier secretie hartritme geheugen genexpressie
38.
Editor's Notes
Allosteric modulators are generally small metabolites or cofactors Homotropic: when modulator is the same as the substrate whereupon conformational changes take place
Merkwaardig, want structureel totaal verschillende van substraten. Dus bindt niet aan actieve site. Zulke sites worden genoemd allosterische of regulator sites. In ATCase enzym liggen actieve site en regulator site op verschillende polypeptide ketens
Ultracentrifuge. A: native B behandeld . De grotere subeenheid is de catalytic subeenheid. Deze subeenheid vertoont catalytische activiteit. Maar reageert niet op CTP en de vertoond geen sigmoidale kinetiek.De katalytische keten bestaat uit 3 ketens (34 kDal) en de regulator subeenheid uit 2 keten. 2 katalytischetrimeren combineren met 3 regulator dimeren.
Quaternaire structuur: 2 catalytische trimeren boven elkaarverbonden door 3 regulator dimeren. Contacten tuusen catalytic en regulator subeenheid. Iedere r keten binnen de regulator dimeer gaat interactie aan met een c keten in het katalytic trimeer. R keten gestabiliseert door Zn dat gebonden is aan 4 cysteine groepen. Hg bindt aan Cys, Zn laat los.