SIG 4
How is carbon allocated to the different parts of the plants?
Carbon is allocated in the phloem. The carbon is then transported from the source leaves to the sink leaves due to a pressure gradient over the phloem canal. The carbon transports through the plasmatic membranes either through plasmodesmata or straight through the membrane walls due to a hydrogen gradient caused by ATP.
What are the source-to-sink expression? What are sink tissues?
Source-to-sink means that the excessive carbon in a source leaf is transported to the sink leaf that is not able to create the carbon they need. Source leaves is adult leaves that is fully grown, and sink leaves is small growing leaves that need more carbon than they can synthesize on their own to grow.
Where in plants is starch and sucrose synthesized?
Sucrose is synthesized in the cytosol. starch is synthesized in leaves, but so is sucrose, weird question.
Describe one model of translocation of carbon in the phloem.
One model is the so called pressure-flow model and is based in the built up pressure gradient in the phloem from the source to the sink. This pressure is not really determined how it is built up , but a hypothesis is that the pressure is built up to a decreasing in solute potential and a rise in the water content. . The carbon is either as said before transported across membranes either through plasmodesmata or straight through the membrane walls.
What else does the phloem sap contains?
The major content is sugar, around 80-100 mg/ml. Then there are some amino acids, organic acids, proteins, potassium, chloride, magnesium, and phosphate.
What are the main forms of sucrose stored and where are they stored?
The main forms of sucrose in plants are starch, fructose and lipids. Starch is stored in the plastid, the fructose is stored in the vacuole and lipids is stored in so called oil bodies.
What is the chemical difference between amylose and cellulose?
The main difference is the bonds, amylose is bond together with alpha 1-4 bonds, and cellulose is bond with beta 1-4 bonds. This enables the celluloses to stack much more tightly than the amylose and disables the humans ability to digest cellulose (break the beta 1-4 bonds).
What are the sources for 1st, 2nd and 3rd generation for biofuels?
1st generation is from maize and corn in USA and sugarcanes in Brazil. 2nd generation is from agricultural waste, lignocellulose for ethanol and grasses. 3rd generation is algae.
What main sources is there for ethanol in Brazil and USA?
In Brazil, the main source is sugarcanes and in USA the main source is corn.
Give examples of 2 plants that are great at capturing CO2 and give a reason why.
Miscanthus and switchgrass is plants called C4 plants and therefore have the ability to reduce the photorespiration by concentring CO2 around the enzyme rubisco. This enables the plants to thrive in environments with higher concentrations of CO2.
What is generally believed to be the capacity of photosynthesis for plants, microalgae and GMO?
plants 1%, microalage 4% and GMO 7%.
What is the difference of biomass from softwood and agriculture?
Biomass from agriculture majorly consists of hemicellulose and cellulose/starch about 40% each. Biomass from softwood consists majorly of 30-50% cellulose and 20-35% hemicellulose along with quite a bit of lignin.
What are the three methods of pretreatment of materials for ethanol production? Describe two characteristics each.
Physical treatment is communition, i.e milling to powder. Radiation with a high energy source, steam/steam explosion under high energy, hydrotermolysis, i.e boiling in high temperatures.
Chemical treatment is treatments with acids, eg. sulfuric acids, phosphoric acids, hydrochloric acids. Treatments with alkali, NaOH, is preferred for agricultural products. Organic solvents like methanol and aceton.
Biological treatments, application with different enzymes that will compose cellulose and requires little energy. Use of different microorganisms that can decompose cellulose.
What are the metabolic action that takes place during the ethanol fermentation?
Reduction is the metabolic action that takes place during fermentation, this is where pyruvate creates acetaldehyde and CO2 using pyruvate decarboxylase enzymes. With usage of NADH this acetaldehyde can then produce ethanol using dehydrogenase enzymes.
Give examples of three biocatalysts active in ethanol fermentation. Give examples of advantages they can have.
Saccarymonas cerevisiae: Cheap, unicellular and has a known behavior.
Zymomonas: Higher sugar uptake and ethanol production, lower biomass biomass production.
Trametes: Can take up hexose and pentose simultaneously, with no inhibition. It can catabolise xylose and hexose under hypoxic conditions.
What is also produced often during pretreatment?
Lignocellulose.