细胞生物学：叶绿体2

1、PhotophosphorylationPhotophosphorylation( (光合磷酸化光合磷酸化) )叶绿体中的ATP到底是怎样合成的? 证明了CF1颗粒就是ATP合成酶，偶联光合磷酸化的装置。类类囊囊体体膜膜重重建建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. 化学渗透学说化学渗透学说:线粒体线粒体 vs 叶叶绿体绿体Photophosphorylation is that the synthesis of ATP is coupled with the electron transfer drived by light. Three types of photophosphorylation in plants and cyanobacteria(蓝藻蓝藻) - Noncyclic photophosphorylation(非非循环式循环式光合磷酸化光合磷酸化) -Cyclic

3、 photophosphorylation(循环式光合循环式光合磷酸化磷酸化) -Pseudocyclic photophosphorylation(假循环假循环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. 电子最终受体电子最终受体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 ,氧接受电子后氧接受电子后,产生产生H2O2，H2O2再转变为再转变为H2O电子从电子从H H2 2O O通过长途传递通过长途传递, ,又到又到H H2 2O, O, 电子好似走了一个循环电子好似走了一个循环, , 为为与真正的循环式电子流相区别与真正的循环式电子流相区别, ,故称为假循环式故称为假循环式光合磷酸化光合磷酸化。Product: H2O2, ATP 最终电子最终电子受体是受体是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). 此项研究的此项研究的主持人卡尔文获得了主持人卡尔文获得了1961年诺贝尔化学奖，并把只年诺贝尔化学奖，并把只具有具有C途径的植物称为途径的植物称

7、为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脱氢甘油醛磷酸脱氢酶酶光反应与暗反光反应与暗反应的连接点应的连接点 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：维管束鞘细胞）.-BSCs are surrounded by a specialized, layer of mesophyll cells CO2 pumpC4 pathway1950s卡尔文等阐明卡尔文等阐明C3途径，途径，CO2还原还原-C3途径途径1954年，哈奇年，哈奇(M.D.Hatch)等发现甘蔗叶中有与等发现甘蔗叶中有与C3途途径不同的光合最初产物，但未受到应有的重视。径不同的光合最初产物，但未受到应有的重视。 In 1965, Hugo Kortschak (美国夏威夷甘蔗栽培研美国夏威夷甘

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，这才引起人，且玉米、甘蔗有很高的光合速率，这才引起人们的注意。们的注意。1966-1970年，澳大利亚的哈奇和斯莱克年，澳大利亚的哈奇和斯莱克(C.R.Slack) 提出了提出了C4-双羧酸途径，简称双羧酸途径，简称C4途径或途径或Hatch-Slack途途径。径。 CO2 -pumping plants are called C4 plants. Al

10、l other plants are called C3 plants. C4植物主要是热带草本植物。植物主要是热带草本植物。至今已知被子植物中有至今已知被子植物中有20多个科约近多个科约近2000种种.CAM (CAM (crassulaceancrassulacean acid metabolismacid metabolism景天景天酸代谢酸代谢) ) 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.菠萝菠萝兰花兰花百合百合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白色体白色体造粉体造粉体有色体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 复 合 物总 数亚 基 数 目胞 质 核 糖 体 合成线 粒 体 核 糖 体 合成细 胞 色 素 氧 化 酶细 胞 色 素 b-c1复 合 物AT P酶核 糖 体 大 亚 基核 糖 体 小 亚 基7793022465302131401Autonomous:(B) chloroplast - About 120 genes in the chloroplast genome of higher plants are highly similar in tobacco and liverwort(地钱). The known gene encoded by ctDNA：4 types o

18、f rRNAs（23S、16S、4.5S, 5S）， tRNA: 20（烟草）or 31（地钱）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（内共生起源学说):Mi or Chl probably evolved from endosymbiotic bacteria endocytosed by early eucaryotic cells(真核细胞真核细胞). - 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