week12-biochemistry--化学专业英语-教学.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,BIOCHEMISTRY(I),-Macromolecular Compounds,大分子化合物,pH of some common items.Image from Purves et al.,Life:The Science of Biology,4th Edition,Structure of a typical plant cell.,Not in animal cells:,Chloroplasts,Central vacuole and tonoplast,Cell wall,Plasmodesma,Structure of an animal cell.,Carbohydrates,碳水化合物,Have the general formula CH,2,O,n,where n is a number between 3 and 6.,Functions:,in short-term energy storage(such as sugar);,as intermediate-term energy storage(starch for plants and glycogen for animals);,as structural components in cells(,cellulose,纤维素,in the,cell walls,of plants and many protists(,原核生物),and chitin in the exoskeleton of insects and other arthropods(,节肢动物,).,Monosaccharides,单糖,Monosaccharides,:,the single(mono=one)sugars.,Important monosaccharides:ribose(C,5,H,10,O,5,),核糖,glucose(C,6,H,12,O,6,),葡萄糖,and fructose,果糖(,same formula but different structure from glucose).,Sugars are structurally the simplest carbohydrates.They are the structural unit which makes up the other types of carbohydrates.,The chain(left)and ring(center and right)method of representing carbohydrates.,Disaccharides,双糖,Formed when,two monosaccharides are chemically bonded together.,Sucrose,蔗糖,a common plant disaccharide,is composed of the monosaccharides glucose and fructose.,Lactose,乳糖,milk sugar,is a disaccharide composed of glucose and the monosaccharide galactose.,Formation of a disaccharide(top)by condensation and structure of two common disaccharides.,Images of starch(top),glycogen(middle),and cellulose(bottom).Image from Purves et al.,Cellulose Fibers from Print Paper(SEM x1,080).,Lipids,脂类,Composed of three fatty acids,脂肪酸(,usually)covalently bonded to a 3-carbon glycerol.,The fatty acids are composed of CH,2,units,and are hydrophobic/not water soluble.,Functions:,Involved mainly with long-term energy storage.,Secondary functions:,as structural components(as in the case of,phospholipids,that are the major building block in cell membranes),as messengers(hormones)that play roles in communications within and between cells.,Saturated(top and middle)and unsaturated(bottom)fatty acids.The term saturated refers to the saturation of the molecule by hydrogen atoms.The presence of a double C=C covalent bond reduces the number of hydrogens that can bond to the carbon chain,hence the application of the term unsaturated.,Phospholipids,磷脂,Important structural components of cell membranes.,Phospholipids are modified so that a,phosphate group,(PO,4,-,)is added to one of the fatty acids.The addition of this group makes a polar head and two nonpolar tails.,Diagram representing the cell membrane.The above image is from.,Cholesterol,胆固醇,and,Steroids,类固醇,Most mention of these two in the news is usually negative.,Cholesterol has many biological uses,such as its occurrence in the cell membranes,and its role in forming the sheath of some neurons.Excess cholesterol in the blood has been linked to atherosclerosis,hardening of the arteries.,Structure of four steroids.,Structure of an amino acid.,Structures in the R-groups of the twenty amino acids found in all living things.,Formation of a peptide bond between two amino acids by the condensation(dehydration)of the amino end of one amino acid and the acid end of the other amino acid.The above image is from.,Structure of a protein:primary,secondary,tertiary,and quaternary levels of structure.,Nucleic acids,核酸,The,polymers,多聚物 composed of,monomer,单体 units known as,nucleotides,核苷酸.,The main functions of nucleotides are information storage(DNA),protein synthesis(RNA),and energy transfers(ATP and NAD).,Nucleotides,Consist of a sugar,a nitrogenous base,and a phosphate.,The sugars are either ribose or deoxyribose,脱氧核糖.,Both are pentoses usually in a ring form.,There are five nitrogenous bases.Purines(,嘌呤,Adenine and Guanine)are double-ring structures,while pyrimidines(,嘧啶,Cytosine,Thymine and Uracil)are single-ringed.,Deoxyribonucleic acid,(DNA),The physical carrier of inheritance for 99%of living organisms.,The bases in DNA are C,G,A and T.,Changes in DNA information will be translated into changes in the,primary structure,of a polypeptide,and from there to the,secondary,and,tertiary,structures.,Mutation,:change in the DNA base sequence.,Most are harmful,and a very few are beneficial and contribute the organisms reproductive success.,The wellspring of variation by,natural selection,.,Structure of a segment of a DNA double helix.,Ribonucleic acid(RNA),Occurs in the nucleus as well as in the cytoplasm,DNA,with exceptions in chloroplasts and mitochondria,is restricted to the nucleus(in eukaryotes,the,nucleoid,region in prokaryotes).,Three types of RNA:,Messenger RNA(mRNA),:the blueprint for construction of a protein.,Ribosomal RNA(rRNA),:the construction site where the protein is made.,Transfer RNA(tRNA),:the truck delivering the proper amino acid to the site,Structure of a RNA molecule.,BIOCHEMISTRY(II),-Metabolism,新陈代谢,Glycolysis,糖酵解,the Universal Process,In the cells cytoplasm where 6-carbon glucose is split into two 3-carbon pyruvate molecules,and some ATP and NADH are produced.,Nine reactions,each catalyzed by a specific enzyme,make up the process,All organisms have glycolysis occurring in their,cytoplasm,胞浆,Graphic summary of the glycolysis process.,烟酰胺腺嘌呤二核苷酸,nicotinamide adenine dinucleotide,Anaerobic Pathways,无氧途径,Anaerobic,conditions:the absence of oxygen,Pyruvic acid:routed into 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 enzymes all under genetic control,are extremely complex.,Alcohol,Fermentation,Fermentation: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 pyruvic acid into ethanol,a C-2 compound.,Fermentation of ethanol.Image from Purves et al.,Fermentation of lactate(lactic acid).Image from Purves et al.,Aerobic Respiration,有氧呼吸,When oxygen is present(aerobic conditions),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.,Overview of the cellular respiration processes.Image from Purves et al,Summary of the Krebs(or citric acid)cycle.Image from Purves et al.,Electron 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,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 passage of electrons is captured as ATP by ADP molecules oxidative phosphorylation.,Figure 8.16An electrogenic pump,Oxidative Phosphorylation,The mechanism-,chemiosmotic,coupling,is the gradient of H,+,ions discovered across the inner mitochondrial 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 enters the ETS chain at the beginning,yielding 3 ATP per NADH.FADH,2,enters at Co-Q,producing only 2 ATP per FADH,2,.,Electron transport system.Images from Purves et al.,Catabolism,分解代谢,and Anabolism,合成代谢,Anabolism,:the total series of chemical 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.Products of catabolism can be reassembled by anabolic processes into new anabolic molecules.,Catabolism and Anabolism,