復旦大學細胞生物學課件06線粒體和葉綠體的能量產生

1、Energy Generation in Mitochondria and ChloroplastsChapter 6(1) Mitochondria: in all eukaryotic cellsThe relationship between the structure and function of mit.(2) Chloroplasts: in plant cellsThe relationship between the structure and function of chl.Mit: Oxidative phosphorylation ATPChl: Photosynthe

2、sis ATP+NADPH SugarA. Mitochondrial structure and functionThe size and number of mitochondria reflect the energy requirements of the cell.1. Mitochondria and oxidative phosphorylationInner and outer mitochondrial membranes enclose two spaces: the matrix and intermembrane space.Outer membrane: Contai

3、ns channel-forming protein, called Porin. Permeable to all molecules of 5000 daltons or less.Inner 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; (3) Transport proteins

4、: Allow the passage of metabolites Intermembrane space: Contains several enzymes use ATP to phosphorylate other nucleotides.Matrix: Enzymes; Mit DNA, Ribosomes, etc.B. Specific functions localized within the Mit by disruption of the organelle and fractionationLocalization of metabolic functions with

5、in the mitochondrionOuter membrane:Phospholipid synthesisfatty acid desaturationFatty acid elongationMark:monoamine oxidaseInner membrane:Electron transportOxidative phosphorylationMetabolite transportCardiolipin/TPL(20%)Mark:cytochrome oxidaseIntermembrane spaceNucleotide phosphorylationMark: adeny

6、late kinaseMatrixPyruvate oxidationTCA cycle oxidation of fatsDNA replication, RNA transcription, Protein translationMark: MDH2. Molecular basis of oxidative phosphorylationA. Molecular basis of oxidation: Electron- transport chainB. Molecular basis of phosphorylation: ATP synthase The structure of

7、the ATP synthaseF1 particle is the catalytic subunit;The F0 particle attaches to F1 and is embedded in the inner membrane.F1: 5 subunits in the ratio 3:3:1:1:1F0: 1a：2b：12c F1 particles have ATP synthase activity Proton translocation through F0 drives ATP synthesis by F1: Binding Change Model and ro

8、tational catalysisBoyer proposed in 1979, and was greatly stimulated by the publication in 1994 of the structure for F1 complex (X-ray) from bovine heart mitochondriaDirect experimental evidence supporting the rotational catalysis.Japan researcher, Nature 386: 300, 1997. The ATP synthase is a revers

9、ible coupling device Other roles for the proton-motive force in addition to ATP synthaseRegulate for Ca2+C. Mithchells Chemiosmotic theory (1961)The pH and electrical gradient resulting from transport of protons links oxidation to phosphorylation.When electrons are passed to carriers only able to ac

10、cept electrons, the H+ is translocated across the inner membrane.More than 21026 molecules (160kg) of ATP per day in our bodies.Electrons pass from NADH or FADH2 to O2, the terminal electron acceptor, through a chain of carriers in the inner membrane (FMN, Fe-S center, Heme group Fe, CoQ);As electro

11、ns move through the electron-transport chain, H+ are pumped out across the inner membrane, and form Proton motive force;Electrons move through the inner membrane via a series of carriers of decreasing redox potentialA testable prediction followed from Mitchells hypothesisIf not all the detergent is

12、removed, what will happen?Summary of the major activities during aerobic respiration in a mitochondrionNADHO2: 3ATP/2e;FADH2 O2 : 2ATP/2e生物氧化產生ATP的統(tǒng)計 一個葡萄糖分子經過細胞呼吸全過程產生多少ATP？ 糖酵解：底物水平磷酸化產生 4 ATP（細胞質） 己糖分子活化消耗 2 ATP（細胞質） 產生 2NADH，經電子傳遞產生 3或 5 ATP （線粒體）凈積累 5 或 7 ATP 丙酮酸氧化脫羧：產生 2NADH（線粒體），生成 5 ATP 三羧酸循

13、環(huán)：底物水平的磷酸化產生（線粒體）2 ATP； 產生 6NADH（線粒體），生成 15 ATP； 產生 2FADH2（線粒體），生成 3 ATP 總計生成 30 或 32 ATP 3. Chloroplast and photosynthesisA. The structure of Chloroplasts B. PhotosynthesisC. The antenna complex and photochemical reaction center in a photosystemLight-dependent reaction: Electron transport in the th

14、ylakoid membrane and noncyclic photophosphorylation: Cyclic photophosphorylation: Changes in redox potential during photosynthesis.Carbon dioxide fixation and the synthesis of carbohydrate in C3 plants (Calvin cycle)The structure and function in C4 plantsCAM plants: CO2被2次固定，但只需1種細胞（Mesophyll cell）4

15、. Organelle DNA and protein importingA. Organelle DNAThe size range of organelle DNA is similar to that of viral DNAs.Mit DNA: from 300000bp (some land plants). DNA of Mit genome(in mammals) 16500bp(0.001% of nuclear genome) ; Chl genomes are about 10 times larger and contain about 120 genes.Chl DNA

16、: from 70000to 200000bp (genome of land plants);Genes in mtDNA encode rRNAs, tRNAs, and some mitochondrial proteinsHuman mt DNA: 16,569bp 2 rRNAs（16s and 12s RNA）, 22 tRNAs, 13 polypeptides: NADH reductase. 7 sub. Cty b-c1 complex. 1 cytb Cyt oxidase. 3 subunits ATP synthase: 2 F0 sub Products of mt

17、 genes are not exported The organization of the liverwort(地錢) Chl genomeB. Mit and Chl have their own genetic systemsMit and Chl are organelles semiautocephaly. The synthesis of mt proteins is coordinatedC. The transport protein into Mit. And Chl. Tree proteins translocators in Mit membranes:TOM, TI

18、M,and OXA complex are multimeric membrane protein, that catalyze protein transport across Mit membrane, TOM, TIM stand for translocase 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 i

19、nsertion of inner membrane proteins that are synthesized 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 import by Mit:N-terminal signal

20、 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 precursor 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 MitProtein transport into the inner Mit membrane and the intermembrane space requires two signal sequencesTwo signal sequences are required to direct proteins to the