ATP H + H + H + H + H + H + H + H + Proton pump Sucrose-H + co transporter Sucrose Sucrose Diffusion of H + - - - - + + + + Electrogenic pumps in plants: Co-transport 1) Active transport Figure 7.21 2) Co-transport 6-26 Figure 7.12 Plasma membrane: Cytoplasmic face Extracellular face Transmembrane glycoprotein Secreted protein Exocytosis – secretion of cellular products Sidedness of membrane Secretory protein Golgi apparatus Vesicle ER ER lumen 6-27 Pseudopodium “Food” or other particle Plasma membrane Vesicle Food vacuole CYTOPLASM Figure 7.22 Receptor Ligand Coat proteins Coated pit Coated vesicle Phagocytosis Pinocytosis Receptor-Mediated Endocytosi EXTRACELLULAR FLUID Solutes Endocytosis – uptake of molecules by the cell 6-28 7-1 Lecture 7. Metabolism: Energetics 1.Thermodynamics 2.Gibb’s free energy 3.ATP energy 4. Activation energy
CONCEPTS The First Law of Thermodynamics à According to the first law of thermodynamics , the energy of the universe is constant à Energy can be transferred and transformed, but it cannot be created or destroyed à The first law is also called the principle of conservaJon of energy 7-2 CONCEPTS The Second Law of Thermodynamics à During energy transfer or transformaJon, some energy becomes unusable, and is oaen lost as heat à According to the second law of thermodynamics: Every energy transfer or transforma,on increases the entropy (disorder) of the universe 7-3 (a) Gravitational motion (b) Diffusion (c) Chemical reaction Increase in Entropy (Disorder) “Order” “Disorder” 7-4 Sunlight à Photosynthesis à Primary biomass à Life on earth - Life (living cells) require energy to make - The ultimate source of energy: sunlight - Light energy is converted to chemical energy - Chemical energy can be used to perform work (H2O) Lehninger: Principles of Biochemistry 7-5
CONCEPTS The Energy of Life à The living cell is a miniature chemical factory where thousands of reacJons occur, constantly à The cell extracts energy stored in ATP and NADH and applies this energy to perform work (biochemical reacJons, biosynthesis, cell growth / maintenance / repair) 7-6 Synthesis Degradation Metabolism Lehninger: Principles of ATP ADP + P i Biochemistry 7-7 Metabolism has to abide by the laws of thermodynamics 1. Conservation of energy . Energy may change form or be transformed but cannot be created or destroyed. 2. Entropy . In all natural processes, the entropy of the universe increases. 3. Transfer or transformation of energy in a cellual processes releases heat Heat Figure 8.3b 7-8 CONCEPTS Metabolism à Metabolism is the totality of an organism’s chemical reacJons à Metabolism is an emergent property of life that arises from orderly interacJons between molecules à A metabolic pathway begins with a specific molecule and ends with a product à Each step is catalyzed by a specific enzyme 7-9
CONCEPTS Metabolism à Anabolic pathways consume energy to build complex molecules from simpler ones (The synthesis of protein from amino acids is an example of anabolism) à Catabolic pathways release energy by breaking down complex molecules into
You've reached the end of your free preview.
Want to read all 84 pages?
- Spring '08