Biology Semester 1 2016 Summary Notes.1.1
Fermentation – In the absence of oxygen (anaerobic), cellular respiration cannot pass on to the Krebs cycle. Consumes NADH. Produces lactate (animals, bacteria) or ethanol (plants, yeast).
Lecture 10 – Photosynthesis Overview of photosynthesis: 6𝐶𝑂2 + 12𝐻2 𝑂 → 𝐶6 𝐻12 𝑂6 + 6𝑂2 + 6𝐻2 𝑂
Light dependent reaction – Photosystem II captures a photon of light. An electron is donated by water when it is split by an enzyme. These cause the excitation of the reaction centre. The electrons are passed along, falling in energy which is used for hydrogen pumping from the stroma to the lumen. Photosystem I then captures another photon of light which is used to form NADPH in the stroma – this further reduces the concentration of H+ ions in the stroma, increasing the gradient between this and the lumen. As the H+ ions are pumped back in to the stroma through ATP synthase, ATP is produced. Cyclic phosphorylation – The electron gets transported back to PS I. Calvin cycle – RuBisCO carbon fixates RuBP to produce phosphoglyceric acid (PGA, 3-carbon). PGA is then phosphorylated by ATP, then, reduced and dephosphorylated by NADPH to form PGAL. PGAL can then follow 3 paths producing either sucrose (cytoplasm), starch (chloroplast) or RuBP.
C4 photosynthesis – Fixes CO2 into a 4C product which is moved in to the bundle sheath. There CO2 is removed and processed in the Calvin cycle. Pyruvate is recycled to the mesophyll. CAM photosynthesis – At night CO2 is converted to malate and stored. During the day stomata closes. CO2 is liberated from the malate and processed in the Calvin cycle.
Lecture 11 – Leaf structure and function General leaf structure:
Palisade mesophyll – Photosynthesis mostly occurs in this region
Isobilateral – Don’t orient either side - are similar on both sides (palisade mesophyll only). Dorsiventral – Has a clear top and bottom side. Top side does most of the photosynthesis and bottom side contains most/all of the stoma for gas exchange with the environment. Heterophylly – Have two different leave types. Heteroblasty – Have different leaves at different stages. Stomata – Are used for gas exchange – releases oxygen and intakes carbon dioxide. H+ ions are pumped out of the guard cells and K+ ions pumped in. Water flows in by osmosis, making guard cells turgid. Under hot conditions, stomata close. Photorespiration – Occurs when stomata are close and oxygen competes with carbon dioxide to bind to RuBisCO. This process only occurs in light and uses ATP. Trichomes – Epidermal hairs trap a boundary layer of air preventing loss of moisture and heat. Glandular – Protective trichomes protect against hebivores. Leaf vascular systems: – Leaf veins contain xylem and phloem. They supply the mesophyll cells with water (xylem) and translocate the sugars made in photosynthesis (phloem). ----------------------------------------------------------------------------------------------------------------------------------------------
Lecture 12 & 13 – Plant nutrition and movement of water and solutes Essential elements – There are 16, most C, H & O. - Parts of structural units. - Parts of metabolomics compounds. - Activate or inhibit enzymes. - Alter osmotic potential in cells. Transport systems: Xylem – Transportation of water from roots to tips. Uses water potential to move water – high to low potential. Water is transpired from leaves which creates a pull all the way down the length of the tree to the roots and then the roots absorb water from the soil. Tracheids – Long, narrow. Overlap. Water moves to adjacent cells through pores. Vessels – Line up end to end. They are more efficient at transporting water.
Lecture 10 – Photosynthesis Overview of photosynthesis: 6𝐶𝑂2 + 12𝐻2 𝑂 → 𝐶6 𝐻12 𝑂6 + 6𝑂2 + 6𝐻2 𝑂
Light dependent reaction – Photosystem II captures a photon of light. An electron is donated by water when it is split by an enzyme. These cause the excitation of the reaction centre. The electrons are passed along, falling in energy which is used for hydrogen pumping from the stroma to the lumen. Photosystem I then captures another photon of light which is used to form NADPH in the stroma – this further reduces the concentration of H+ ions in the stroma, increasing the gradient between this and the lumen. As the H+ ions are pumped back in to the stroma through ATP synthase, ATP is produced. Cyclic phosphorylation – The electron gets transported back to PS I. Calvin cycle – RuBisCO carbon fixates RuBP to produce phosphoglyceric acid (PGA, 3-carbon). PGA is then phosphorylated by ATP, then, reduced and dephosphorylated by NADPH to form PGAL. PGAL can then follow 3 paths producing either sucrose (cytoplasm), starch (chloroplast) or RuBP.
C4 photosynthesis – Fixes CO2 into a 4C product which is moved in to the bundle sheath. There CO2 is removed and processed in the Calvin cycle. Pyruvate is recycled to the mesophyll. CAM photosynthesis – At night CO2 is converted to malate and stored. During the day stomata closes. CO2 is liberated from the malate and processed in the Calvin cycle.
Lecture 11 – Leaf structure and function General leaf structure:
Palisade mesophyll – Photosynthesis mostly occurs in this region
Isobilateral – Don’t orient either side - are similar on both sides (palisade mesophyll only). Dorsiventral – Has a clear top and bottom side. Top side does most of the photosynthesis and bottom side contains most/all of the stoma for gas exchange with the environment. Heterophylly – Have two different leave types. Heteroblasty – Have different leaves at different stages. Stomata – Are used for gas exchange – releases oxygen and intakes carbon dioxide. H+ ions are pumped out of the guard cells and K+ ions pumped in. Water flows in by osmosis, making guard cells turgid. Under hot conditions, stomata close. Photorespiration – Occurs when stomata are close and oxygen competes with carbon dioxide to bind to RuBisCO. This process only occurs in light and uses ATP. Trichomes – Epidermal hairs trap a boundary layer of air preventing loss of moisture and heat. Glandular – Protective trichomes protect against hebivores. Leaf vascular systems: – Leaf veins contain xylem and phloem. They supply the mesophyll cells with water (xylem) and translocate the sugars made in photosynthesis (phloem). ----------------------------------------------------------------------------------------------------------------------------------------------
Lecture 12 & 13 – Plant nutrition and movement of water and solutes Essential elements – There are 16, most C, H & O. - Parts of structural units. - Parts of metabolomics compounds. - Activate or inhibit enzymes. - Alter osmotic potential in cells. Transport systems: Xylem – Transportation of water from roots to tips. Uses water potential to move water – high to low potential. Water is transpired from leaves which creates a pull all the way down the length of the tree to the roots and then the roots absorb water from the soil. Tracheids – Long, narrow. Overlap. Water moves to adjacent cells through pores. Vessels – Line up end to end. They are more efficient at transporting water.
