細胞生物學：葉綠體2

1、PhotophosphorylationPhotophosphorylation( (光合磷酸化光合磷酸化) )葉綠體中的ATP到底是怎樣合成的? 證明了CF1顆粒就是ATP合成酶，偶聯(lián)光合磷酸化的裝置。類類囊囊體體膜膜重重建建ATP synthase： CF1-CF0-ATPase complex is distributed over the thylakoid membrane, and consists of CF1 and CF0. CF1 made of 5 kinds of polypeptides of , , , and. CF0 consists of at less t

2、h r e e t y p e s o f polypeptides. 化學滲透學說化學滲透學說:線粒體線粒體 vs 葉葉綠體綠體Photophosphorylation is that the synthesis of ATP is coupled with the electron transfer drived by light. Three types of photophosphorylation in plants and cyanobacteria(藍藻藍藻) - Noncyclic photophosphorylation(非非循環(huán)式循環(huán)式光合磷酸化光合磷酸化) -Cyclic

3、 photophosphorylation(循環(huán)式光合循環(huán)式光合磷酸化磷酸化) -Pseudocyclic photophosphorylation(假循環(huán)假循環(huán)式光合磷酸化式光合磷酸化) Noncyclic photophosphorylation: H2Oe- PSII cytb6/f-PSI - NADPH. In the process, the path for electron transfer is an open route.Product: slightly more than 1 molecule of ATP, 1 molecule of NADPH and O2 for

4、 every pair of electrons. 電子最終受體電子最終受體Cyclic photophosphorylation: PSI the primary acceptor of PSI Fd cytb6-f complex Pc PSI Product: only ATP. - The type of photophosphorylation accounts for about 10-20% of the total photophosphorylation. Pseudo-cyclic photophosphorylation: H2OP680 cytb6/f P700 Fd

5、O2 ,氧接受電子后氧接受電子后,產(chǎn)生產(chǎn)生H2O2，H2O2再轉變?yōu)樵俎D變?yōu)镠2O電子從電子從H H2 2O O通過長途傳遞通過長途傳遞, ,又到又到H H2 2O, O, 電子好似走了一個循環(huán)電子好似走了一個循環(huán), , 為為與真正的循環(huán)式電子流相區(qū)別與真正的循環(huán)式電子流相區(qū)別, ,故稱為假循環(huán)式故稱為假循環(huán)式光合磷酸化光合磷酸化。Product: H2O2, ATP 最終電子最終電子受體是受體是O22) Dark reaction Dark reaction: Chloroplasts harness NADPH and ATP produced by light reaction to r

6、educe CO2 and produce glucose in the stroma. C 3 c y c l e ( t h e i n i t i a l p r o d u c t i s 3 -phosphoglyceric acid (3-磷酸甘油酸磷酸甘油酸) or Calvin cycle (In 1950s, the path was discovered by Calvin using 14C tracer technique). 此項研究的此項研究的主持人卡爾文獲得了主持人卡爾文獲得了1961年諾貝爾化學獎，并把只年諾貝爾化學獎，并把只具有具有C途徑的植物稱為途徑的植物稱

7、為C植物植物。3CO2+9ATP+6NADPH+H2O glyceraldehyde 3-phosphate +8Pi +9ADP+6NADP+ 3-磷酸甘油醛5-磷酸核酮糖激酶磷酸核酮糖激酶ribulose-1,5-bisphosphate carboxylase磷酸甘油磷酸甘油酸酸激酶激酶甘油醛磷酸脫氫甘油醛磷酸脫氫酶酶光反應與暗反光反應與暗反應的連接點應的連接點 Hot or dry conditions can favor photorespiration? such as corn(玉米) and sugar cane（甘蔗） growing in hot, dry environm

8、ents-specialized bundle-sheath cells（BSCs：維管束鞘細胞）.-BSCs are surrounded by a specialized, layer of mesophyll cells CO2 pumpC4 pathway1950s卡爾文等闡明卡爾文等闡明C3途徑，途徑，CO2還原還原-C3途徑途徑1954年，哈奇年，哈奇(M.D.Hatch)等發(fā)現(xiàn)甘蔗葉中有與等發(fā)現(xiàn)甘蔗葉中有與C3途途徑不同的光合最初產(chǎn)物，但未受到應有的重視。徑不同的光合最初產(chǎn)物，但未受到應有的重視。 In 1965, Hugo Kortschak (美國夏威夷甘蔗栽培研美國夏威夷甘

9、蔗栽培研究所究所) discovered that the radioactive 14C first lies in four-carbon compounds (C4二羧酸二羧酸)instead of PGA，且玉米、甘蔗有很高的光合速率，這才引起人，且玉米、甘蔗有很高的光合速率，這才引起人們的注意。們的注意。1966-1970年，澳大利亞的哈奇和斯萊克年，澳大利亞的哈奇和斯萊克(C.R.Slack) 提出了提出了C4-雙羧酸途徑，簡稱雙羧酸途徑，簡稱C4途徑或途徑或Hatch-Slack途途徑。徑。 CO2 -pumping plants are called C4 plants. Al

10、l other plants are called C3 plants. C4植物主要是熱帶草本植物。植物主要是熱帶草本植物。至今已知被子植物中有至今已知被子植物中有20多個科約近多個科約近2000種種.CAM (CAM (crassulaceancrassulacean acid metabolismacid metabolism景天景天酸代謝酸代謝) ) About less than 5% plants living in hot, dry desert conditions, also f i x C O2 u s i n g P E P carboxylase. These plan

11、ts are called CAM plants.菠蘿菠蘿蘭花蘭花百合百合Both stage1 and stage2 require light energy directly, and stage3 requires light energy only indirectly. Summary of photosynthesis 1）Absorption, transfer and conversion of sunlight energy 2） Electric energy conversion into active chemical energy by electron transf

12、er and photosynthetic phosphorylation；3）The active chemical energy conversion into steady one by carbon assimilation. The significance of photosynthesis CO2O2?3.Development of chloroplasts白色體白色體造粉體造粉體有色體4. Genetic systems of Mi or Chl DNA structure:(A)mitochondria:- double-stranded cyclic DNA that n

13、ot bind histones.- size of mtDNA: mitochondria DNAs: less than 6103 bpmore than 3105 bp (some land plants)(B)Chloroplast(B)Chloroplast: : - the mixture of cyclic DNA and linear DNA molecules in which linear molecules outnumber cyclic ones.- Size of ctDNA: 2105-2.5106 bp Mitochondria or chloroplasts

14、contain complete genetic systems Chloroplast:Chloroplast: - Chloroplast genes are involved in four main types of processes: transcription, translation, photosynthesis, and the biosynthesis of small molecules such as amino acids, fatty acids, and pigments. - chloroplasts have their own DNA as well as

15、 ribosomes.Semi-autonomous organelle： -Mitochondria and chloroplast contain less genetic information, limited types of proteins encoded oneself, protein synthetic system is highly dependent on nuclear genome though they have their own genomes as well as their own biosynthetic machinery for making RN

16、A and organelle proteins. Genes encoded by mitochondria or chloroplasts(A)Mitochondria -Human mtDNA：37 genes(12S,16S rRNA；22 types of tRNAs；13 types of polypeptides： 7 subunits of NADH dehydrogenase，one cytb of cytb-c1 complex，three subunits of cytochrome C oxidase, two F0 subunits of ATP synthetase

17、.) 酶 復 合 物總 數(shù)亞 基 數(shù) 目胞 質 核 糖 體 合成線 粒 體 核 糖 體 合成細 胞 色 素 氧 化 酶細 胞 色 素 b-c1復 合 物AT P酶核 糖 體 大 亞 基核 糖 體 小 亞 基7793022465302131401Autonomous:(B) chloroplast - About 120 genes in the chloroplast genome of higher plants are highly similar in tobacco and liverwort(地錢). The known gene encoded by ctDNA：4 types o

18、f rRNAs（23S、16S、4.5S, 5S）， tRNA: 20（煙草）or 31（地錢）and about more than 90 types of polypeptide (11 or 8 types of ribosomal proteins in small subunit and large subunit ). Most Mitochondria and chloroplast proteins are encoded by nuclear genomeNonautonomous:5 . Origin of Mi or Chl Endosymbiosis hypothesis（內(nèi)共生起源學說):Mi or Chl probably evolved from endosymbiotic bacteria endocytosed by early eucaryotic cells(真核細胞真核細胞). - Mi probably may descend from a type of gram-negative bacterium that carry out TCA and transfering electrons - Chl is likely to descend from a partic