Lecture Notes for Sept. 30, 2008

Additional Photosynthesis Topics ? How do desert plants (cacti) photosynthesis in the intense desert heat ? night take in CO2 through pores ? create NADPH and ADP during the day ? grow very slowly ? Aquatic plants ? blue tint- travels deeper ? pigments that absorbs blue light waves ? Algae- 30% to 50%- efficient- producing glucose ? Sunlight vs. little sunlight ? Why do leaves change colors in the fall ? shorter days- reduction in photoperiod ? senescence hormones trigger shutdown in leaves ? Abscission layer forms between leaves and stems ? reduces H2O transport to leaf ? reduced photosynthesis ? chlorophyll breaks down ? exposes other pigments in leaves ? Deciduous trees- leaves fall off (Blacksburg) ? Sensitivity of plants to changes in CO2 Photorespiration ? under conditions of: ? intense light ? high temp. ? low humidity ? high transpiration (H2O loss) ? stomata in the leaf close down ? No gasses exchanged no CO2 ? No calvin- benson cycle ? An attempt to canabolize NADPH to make NADP to keep the photosystems going C4 Photosynthesis ? sugar cane ? crab grass ? extremely hot conditions Energy transformation organelles ? Mitochondrion/ria (plural) ? produce energy (ATP synthesis) ? many biochemical operations related to cellular respiration ? double membrane, folded series (Cristae)- site of reactions ? own DNA and semi- autonomous ? come from pre-existing mitochondria ? more in active cells C6H12O6 ? Where is the energy? ? Carbon- no framework ? Oxygen- no H2O ? Hydrogen- yes excited electrons Cellular Respiration ? Aerobic ? Glycolysis- splitting glucose ? TCA cycle (Kreb's)- products of ATP and NADH and CO2 ? Electrot transport- energy exchange Glycolysis Inventory ? Input ? 1 Glucose ? 2 ATP ? 2 ADP + 2Pi ? 2 NAD ? Output ? 2 Pyruvate (3 carbons) ? 4 ATP ? 2 NADH ? Net yield ? 2 ATP ? 2 NADH ? 2 Pyruvate ? No oxygen used ? occurs in cytoplasm of the cell