線綠體和葉綠體

1、Energy Generation in Mitochondria and Chloroplasts,Chapter 7,(1) Mitochondria: in all eukaryotic cells The relationship between the structure and function of mit.(2) Chloroplasts: in plant cells The rela

2、tionship between the structure and function of chl.,Mit: Oxidative phosphorylation → ATPChl: Photosynthesis → ATP + NADPH → Sugar,A. Mitochondrial structure and function,The size and number of mitochondria reflect the

3、energy requirements of the cell.,1. Mitochondria and oxidative phosphorylation,Figure 7-4 Relationship between mitochondria and microtubules.,Figure 7-3 Mitochondrial plasticity.   

4、0;Rapid changes of shape are observed when a mitochondrion is visualized in a living cell.,Figure 7-5 Localization of mitochondria near sites of high ATP utilization in cardiac muscle and a sperm tail.,,Inner a

5、nd outer mitochondrial membranes enclose two spaces: the matrix and intermembrane space.,Outer membrane: Contains channel-forming protein, called Porin. Permeable to all molecules of 5000 daltons or less.,Inner

6、membrane (Impermeability): Contains proteins with three types of functions:(1) Electron-transport chain: Carry out oxidation reactions; (2) ATP synthase: Makes ATP in the matrix;

7、(3) Transport proteins: Allow the passage of metabolites,Intermembrane space: Contains several enzymes use ATP to phosphorylate other nucleotides.,Matrix: Enzymes; Mit DNA, Ribosomes, etc.,,Figure 14-6 Fracti

8、onation of purified mitochondria into separate components.    These techniques have made it possible to study the different proteins in each mitochondrial compartment. The method shown, which allows t

9、he processing of large numbers of mitochondria at the same time, takes advantage of the fact that in media of low osmotic strength water flows into mitochondria and greatly expands the matrix space (yellow). While the cr

10、istae of the inner membrane allow it to unfold to accommodate the expansion, the outer membranewhich has no folds to begin withbreaks, releasing a structure composed of only the inner membrane and the matrix.,B. Specific

11、 functions localized within the Mit by disruption of the organelle and fractionation,Localization of metabolic functions within the mitochondrion,Outer membrane:,Phospholipid synthesis,fatty acid desaturation,Fatty acid

12、elongation,Inner membrane:,Electron transport,Oxidative phosphorylation,Metabolite transport,Intermembrane space,Nucleotide phosphorylation,Matrix,Pyruvate oxidation,TCA cycle,ß oxidation of fats,DNA replication, RN

13、A transcription, Protein translation,2. Molecular basis of oxidative phosphorylation,A. Molecular basis of oxidation: Electron- transport chain,,,B. Molecular basis of phosphorylation: ATP synthase,T

14、he structure of the ATP synthase,F1 particle is the catalytic subunit;The F0 particle attaches to F1 and is embedded in the inner membrane.,,F1: 5 subunits in the ratio 3?:3?:1?:1?:1?,F0: 1a：2b：12c,F1 particles have ATP

15、 synthase activity,Proton translocation through F0 drives ATP synthesis by F1: Binding Change Model and rotational catalysis,Boyer proposed in 1979, and was greatly stimulated by the publication in 1994 of the structure

16、for F1 complex (X-ray) from bovine heart mitochondria,,Direct experimental evidence supporting the rotational catalysis.,Japan researcher, Nature 386: 300, 1997.,The ATP synthase is a reversible coupling device,Other rol

17、es for the proton-motive force in addition to ATP synthase,C. Mithchell’s Chemiosmotic theory (1961),The pH and electrical gradient resulting from transport of protons links oxidation to phosphorylation.,Wh

18、en electrons are passed to carriers only able to accept electrons, the H+ is translocated across the inner membrane.,More than 2?1026 molecules (>160kg) of ATP per day in our bodies.,Electrons pass from NADH or FADH2

19、to O2, the terminal electron acceptor, through a chain of carriers in the inner membrane (FMN, Fe-S center, Heme group Fe, CoQ);As electrons move through the electron-transport chain, H+ are pumped out across the inner

20、 membrane, and form Proton motive force;Electrons move through the inner membrane via a series of carriers of decreasing redox potential,If not all the detergent is removed, what will happen?,,Figure 7-26 An e

21、xperiment demonstrating that the ATP synthase is driven by proton flow.    By combining a light-driven bacterial proton pump (bacteriorhodopsin), an ATP synthase purified from ox heart mitochondria, a

22、nd phospholipids, vesicles were produced that synthesized ATP in response to light.,Summary of the major activities during aerobic respiration in a mitochondrion,NADH?O2: 3ATP/2e;FADH2 ?O2 : 2ATP/2e,?生物氧化產(chǎn)生ATP的統(tǒng)計

23、 一個葡萄糖分子經(jīng)過細胞呼吸全過程產(chǎn)生多少ATP？ 糖酵解：底物水平磷酸化產(chǎn)生 4 ATP（細胞質） 己糖分子活化消耗 2 ATP（細胞質） 產(chǎn)生 2NADH，經(jīng)電子傳遞產(chǎn)生 4或 6 ATP （線粒體）凈積累 6或8 ATP 丙酮酸氧化脫羧：產(chǎn)生 2NADH（線粒體），生成 6ATP

24、 三羧酸循環(huán)：底物水平的磷酸化產(chǎn)生（線粒體）2ATP； 產(chǎn)生 6NADH（線粒體），生成 18ATP； 產(chǎn)生 2FADH2（線粒體），生成 4 ATP 總計生成 36或38 ATP,3. Chloroplast and photosynthesis,A. Comparison of a mitochondrion

25、 and a chloroplast.,Figure 14-39 The chloroplast.    This photosynthetic organelle contains three distinct membranes (the outer membrane, the inner membrane, and the thylakoid membrane) that

26、 define three separate internal compartments (the intermembrane space, the stroma, and the thylakoid space). The thylakoid membrane contains all of the energy-generating systems of the chloroplast. In electron micrograph

27、s this membrane appears to be broken up into separate units that enclose individual flattened vesicles (see Figure 14-40), but these are probably joined into a single, highly folded membrane in each chloroplast. As indic

28、ated, the individual thylakoids are interconnected, and they tend to stack to form aggregates called grana.,(A) A wheat leaf cell in which a thin rim of cytoplasm containing chloroplasts surrounds a large vacuole. (B) A

29、thin section of a single chloroplast, showing the starch granules and lipid droplets that have accumulated in the stroma as a result of the biosyntheses occurring there. (C) A high-magnification view of a granum, showing

30、 its stacked thylakoid membrane. (Courtesy of K. Plaskitt.),,,Figure 7-42 Photosynthesis in a chloroplast.    Water is oxidized and oxygen is released in the photosynthetic electron-transfer

31、 reactions, while carbon dioxide is assimilated (fixed) to produce carbohydrate in the carbon-fixation reactions.,B. Photosynthesis,C. The antenna complex and photochemical reaction center in a photosystem,Light-depend

32、ent reaction: Electron transport in the thylakoid membrane and noncyclic photophosphorylation:,,Cyclic photophosphorylation:,Changes in redox potential during photosynthesis.,Carbon dioxide fixation and the synthesis of

33、carbohydrate in C3 plants (Calvin cycle),Figure 14-43 The initial reaction in carbon fixation.    This reaction, in which carbon dioxide is converted into organic carbon, is catalyzed in the

34、 chloroplast stroma by the abundant enzyme ribulose bisphosphate carboxylase. The product, 3-phosphoglycerate, is also an important intermediate in glycolysis: the two carbon atoms shaded in blue are used to produce phos

35、phoglycolate when the enzyme adds oxygen instead of CO2。,The structure and function in C4 plants,4. Organelle DNA and protein importing,A. Organelle DNA,The size range of organelle DNA is similar to that of viral DNAs.

36、Mit DNA: from 300,000bp (some land plants). DNA of Mit genome (in mammals) ≈16,500bp(<0.001% of nuclear genome) ; Chl genomes are about 10 times larger and contain about 120 genes.Chl DNA: from 70,000?to 200,000bp

37、(genome of land plants);,Genes in mtDNA encode rRNAs, tRNAs, and some mitochondrial proteinsHuman mt DNA: 16,569bp 2 rRNAs, 22 tRNAs, 13 polypeptides: NADH reductase. 7 sub.

38、 Cty b-c1 complex. 1 cytb Cyt oxidase. 3 subunits ATP synthase: 2 F0 sub,Products of mt

39、genes are not exported,The organization of the liverwort(地錢) Chl genome,B. Mit and Chl have their own genetic systems,Mit and Chl are organelles semiautocephaly. The synthesis of mt proteins is coordinated,C. The tran

40、sport protein into Mit. And Chl.,,Tree proteins translocators in Mit membranes:,TOM, TIM,and OXA complex are multimeric membrane protein, that catalyze protein transport across Mit membrane, TOM, TIM stand for translocas

41、e of the outer and inner Mit membranes respectively.TOM functions across the outer membrane; TIM(TIM23 and TIM22) function across the inner membrane.OXA mediates the insertion of inner membrane proteins that are synthe

42、sized within the Mit. OXA also helps TOM and TIM to insert some proteins into the matrix.,Translocation of precursors to the matrix occurs at the sites where the outer and inner membranes are close together;,The protein

43、import by Mit:,N-terminal signal sequence is recognized by receptors of TOM; The protein is translocated across both Mit membranes at or near special contact sites.,Only unfolded proteins can be imported into Mit;,Mit pr

44、ecursor proteins remain unfolded through interactions with hsp70 chaperone proteins in the cytosol after they are synthesized.,ATP hydrolysis and H+ gradient are used to dtive protein import into Mit,Protein transport in

45、to the inner Mit membrane and the intermembrane space requires two signal sequences,Two signal sequences are required to direct proteins to the Thylakoid membrane in Chl.,Translocation into thylakoid space or thylakoid M

46、 can occur by any one of at least four routes.,5. The proliferation and origin of Mit and Chl.,A. Organelle growth and division determine the number of Mitochondria and Plastids in a cell,Mit fission and fusion (a div

47、iding Mit in a liver cell); Dividing or Budding of Mit. Chloroplasts: dividing and formation of chloroplasts from proplastids begins by the light-induced budding of the inner membrane.,B. Origin: The endosymbiont theor