生物化学BIOCHEMISTRY专业英语Metabolism新陈代谢课件

1、生物化学BIOCHEMISTRY生物化学BIOCHEMISTRY Metabolism 新陈代谢 Metabolism 新陈代谢Glycolysis 糖酵解 the Universal Process In the cells cytoplasm胞浆where 6-carbon glucose is split into two 3-carbon pyruvate 丙酮酸盐molecules, and some ATP and NADH are produced. Nine reactions, each catalyzed by a specific enzyme, make up the

2、process All organisms have glycolysis occurring in their cytoplasmGlycolysis 糖酵解 the UniversalGraphic summary of the glycolysis process. 烟酰胺腺嘌呤二核苷酸nicotinamide adenine dinucleotideGraphic summary of the glycolyAnaerobic Pathways 无氧途径Anaerobic conditions: the absence of oxygen Pyruvic acid: routed in

3、to one of three pathways: lactic acid fermentation 乳酸发酵alcohol fermentation 酒精发酵cellular (anaerobic) respiration 细胞呼吸. Humans cannot ferment alcohol in their own bodies, we lack the genetic information to do so. These biochemical pathways, with their myriad reactions catalyzed by reaction-specific e

4、nzymes all under genetic control, are extremely complex. Anaerobic Pathways 无氧途径AnaerobAlcohol FermentationFermentation: the formation of alcohol from sugar. Yeast, when under anaerobic conditions, convert glucose to pyruvic acid via the glycolysis pathways, then go one step farther, converting pyru

5、vic acid into ethanol, a C-2 compound.Alcohol FermentationFermentatiFermentation of ethanol. Image from Purves et al.Fermentation of ethanol. ImageFermentation of lactate (lactic acid). Image from Purves et al. Fermentation of lactate (lactiAerobic Respiration 有氧呼吸When oxygen is present (aerobic con

6、ditions), most organisms will undergo two more steps, Krebs Cycle, and Electron Transport, to produce their ATP. In eukaryotes 真核细胞, these processes occur in the mitochondria线粒体, while in prokaryotes原核细胞 they occur in the cytoplasm.Aerobic Respiration 有氧呼吸When oOverview of the cellular respiration p

7、rocesses. Image from Purves et alOverview of the cellular respiSummary of the Krebs (or citric acid) cycle. Image from Purves et al.Summary of the Krebs (or citrElectron Transport Phosphorylation 电子传递磷酸化Krebs cycle completely oxidized the carbons in the pyruvic acids, producing a small amount of ATP

8、, and reducing NAD and FAD into higher energy forms. Electron Transport System (ETS): Its chemical is embedded in the membranes The higher energy forms are cashed in, producing ATP. Cytochromes are molecules that pass the hot potatoes (electrons) along the ETS chain. Energy released by the downhill

9、passage of electrons is captured as ATP by ADP molecules oxidative phosphorylation. Electron Transport PhosphorylaFigure 8.16An electrogenic pumpFigure 8.16An electrogenic pOxidative PhosphorylationThe mechanism - chemiosmotic coupling, is the gradient of H+ ions discovered across the inner mitochon

10、drial membrane. Involves both chemical and transport processes. Drops in the potential energy of electrons moving down the ETS chain occur at three points. These points turn out to be where ADP + P are converted into ATP. Potential energy is captured by ADP and stored in the pyrophosphate bond. NADH

11、 enters the ETS chain at the beginning, yielding 3 ATP per NADH. FADH2 enters at Co-Q, producing only 2 ATP per FADH2.Oxidative PhosphorylationThe mElectron transport system. Images from Purves et al.Electron transport system. ImaCatabolism 分解代谢and Anabolism合成代谢 Anabolism: the total series of chemic

12、al reactions involved in synthesis of organic compounds. Autotrophs must be able to manufacture (synthesize) all the organic compounds they need. Heterotrophs can obtain some of their compounds in their diet (along with their energy). For example humans can synthesize 12 of the 20 amino acids, we must obtain the other 8 in our diet. Catabolism: the series of chemical reactions that breakdown larger molecules. Energy is released this way, some of it can be utilized for anabolism. Product