大學(xué)生物專(zhuān)業(yè)英語(yǔ)lesson-two.ppt

1、2020/9/16,Lesson Two Photosynthesis,2020/9/16,教學(xué)目的：使學(xué)生掌握細(xì)胞的光合作用機(jī)理，光合系統(tǒng)與光合系統(tǒng)結(jié)構(gòu)與功能之間的關(guān)系。相關(guān)英語(yǔ)詞匯以及主要用法。 教學(xué)重點(diǎn)：光合作用中相關(guān)的概念和功能，及相關(guān)英語(yǔ)詞匯的掌握 教學(xué)難點(diǎn)：專(zhuān)業(yè)英語(yǔ)詞匯的記憶,2020/9/16,Photosynthesis n.光合作用 Chlorophyll n.葉綠素 Protist n.原生生物 Exergonic a.放能的 Endergonic a.吸能的 Chloroplast n.葉綠體 Thylakoid n.類(lèi)囊體,Glossary,2020/9/16,Phot

2、osynthesis occurs only in the chlorophyll-containing cells of green plants, algae, and certain protists and bacteria. 光合作用只發(fā)生在含有葉綠素的綠色植物細(xì)胞，藻類(lèi)，某些原生生物和細(xì)菌之中。,Introduction,2020/9/16,Overall, it is a process that converts light energy into chemical energy that is stored in the form of molecular bonds. 總體

3、來(lái)說(shuō)，這是一個(gè)將光能轉(zhuǎn)化成化學(xué)能，并將能量貯存在分子鍵中。,2020/9/16,From the point of view of chemistry and energetics, it is the opposite of cellular respiration. 從化學(xué)和熱力學(xué)(動(dòng)能學(xué))角度來(lái)看，它是細(xì)胞呼吸作用的逆反應(yīng) Whereas cellular respiration is highly exergonic and releases energy, photosynthesis requires energy and is highly endergonic. 但是細(xì)胞呼吸作

4、用是高度放能的，光合作用是需要能量的,并且是高度吸能的過(guò)程。,2020/9/16,Photosynthesis starts with CO2 and H2O as raw materials and proceeds through two sets of partial reactions. 光合作用以二氧化碳和水為原材料并經(jīng)歷兩步化學(xué)反應(yīng)。 In the first set, called the light-dependent reactions, water molecules are split (oxidized), O2 is released, and ATP and NAD

5、PH are formed. 第一步，稱(chēng)光反應(yīng)，水分子裂解（分解）(被氧化)，氧分子被釋放，ATP和NADPH形成。 These reactions must take place in the presence of light energy. 此反應(yīng)必須在存在光能的條件下發(fā)生。,2020/9/16,2020/9/16,In the second set, called light-independent reactions, CO2 is reduced (via the addition of H atoms) to carbohydrate. 第二步，稱(chēng)暗反應(yīng)，二氧化碳被還原成碳水化合

6、物。 These chemical events rely on the electron carrier NADPH and ATP generated by the first set of reactions. 這步反應(yīng)依賴(lài)于由第一步反應(yīng)產(chǎn)生的電子載體NADPH以及ATP。,2020/9/16,2020/9/16,Both sets of reactions take place in chloroplasts. 兩步反應(yīng)都發(fā)生在葉綠體中。 Most of the enzymes and pigments for the light-dependent reactions are emb

7、edded in the thylakoid membrane of chloroplasts. 光反應(yīng)需要的大部分酶和色素都是包埋在葉綠體的類(lèi)囊體膜上。 The dark reactions take place in the stroma. 暗反應(yīng)發(fā)生在基質(zhì)中。,2020/9/16,1. How light energy reaches photosynthetic cells光合細(xì)胞如何吸收光能的,2020/9/16,Glossary absorption spectrum：吸收光譜 Carotenoid：類(lèi)胡蘿卜素 Antenna：天線、觸角 Funnel：漏斗、煙窗 Aggregat

8、ion：集合體、聚合 Photosystem：光系統(tǒng),2020/9/16,The energy in light photons in the visible part of the spectrum can be captured by biological molecules to do constructive work. 生物分子能捕獲可見(jiàn)光譜中光子的能量。 The pigment chlorophyll in plant cells absorbs photons within a particular absorption spectruma statement of the am

9、ount of light absorbed by chlorophyll at different wavelengths. 植物細(xì)胞中的葉綠素可以吸收特定吸收光譜中的光子。,2020/9/16,When light is absorbed it alters the arrangement of electrons in the absorbing molecule. 在吸收光能時(shí),光可以改變捕光分子中的電子排列。 The added energy of the photon boosts the energy condition of the molecule from a stable

10、 state to a less-stable excited state. 光子的能量激活了分子的能量狀態(tài)，使其從基態(tài)（穩(wěn)定態(tài)）進(jìn)入激發(fā)態(tài)（不穩(wěn)定的）。,2020/9/16,During the light-dependent reactions of photosynthesis, as the absorbing molecule returns to the ground state, the “excess” excitation energy is transmitted to other molecular and stored as chemical energy. 在光合作用

11、的光反應(yīng)中,當(dāng)捕光分子回到基態(tài)時(shí),額外的激發(fā)能被轉(zhuǎn)移到其它分子中并且以化學(xué)能的形式貯存.,2020/9/16,All photosynthetic organisms contain various classes of chlorophylls and one or more carotenoid pigments that also contribute to photosynthesis. 所有的光合生物都含有各種類(lèi)型的葉綠素和一種或多種與光合作用相關(guān)的類(lèi)胡蘿卜素分子（光合作用的輔助色素）。 Groups of pigment molecules called antenna compl

12、exes are present on thylakoids. 天線色素分子群（稱(chēng)作天線復(fù)合體的色素分子群）存在于類(lèi)囊體中。,2020/9/16,Light striking any one of the pigment molecules is funneled to a special chlorophyll a molecule, termed a reaction-center chlorophylls, which directly participates in photosynthesis。 激活色素分子的光能象進(jìn)入漏斗一樣被轉(zhuǎn)移到直接參與光合作用的反應(yīng)中心葉綠素分子中。,202

13、0/9/16,Most photosynthetic organisms possess two types of reaction-center chlorophylls, P680 and P700, each associated with an electron acceptor molecule and an electron donor molecule. 大多數(shù)光合生物含有兩個(gè)反應(yīng)中心葉綠素分子，P680和P700，每個(gè)都與電子受體和電子供體相連。 These aggregations are known respectively as photosystem I (P700)

14、and photosystem II (P680). 這些集合體分別是大家熟知的光系統(tǒng)和光系統(tǒng) 。,2020/9/16,2.The light-dependent reaction: converting solar energy into chemical-bond energy光反應(yīng)：太陽(yáng)能轉(zhuǎn)化成化學(xué)能,2020/9/16,Cleave v.裂開(kāi)、劈開(kāi) Plastiquinone n.質(zhì)醌 Ferredoxin n.生化鐵氧化還原蛋白 Coenzyme 輔酶 Photophosphorylation 光合磷酸化 noncyclic photophosphorylation 非環(huán)形光合磷酸化

15、 ribulose biphosphate 核酮糖二磷酸 carboxylase n. 羧(基)酶, 羧化酶,2020/9/16,photorespiration n.生化光呼吸(作用) Anatomy n.剖析, 解剖學(xué) arid adj.干旱的, 貧瘠的(土地等), 無(wú)趣的, 沉悶的 lessen v.減少, 減輕,2020/9/16,The photosystems of the light-dependent reactions are responsible for the packaging of light energy in the chemical compounds ATP

16、 and NADPH. 光反應(yīng)的光系統(tǒng)將光能轉(zhuǎn)化成化合物（化學(xué)復(fù)合物）ATP和NADPH。,2020/9/16,This packaging takes place through a series of oxidation-reduction reactions set in motion when light strikes the P680 reaction center in photosystem II. 當(dāng)光激活光系統(tǒng)的光反應(yīng)中心時(shí)，該轉(zhuǎn)化過(guò)程是通過(guò)一系列的氧化還原反應(yīng)來(lái)實(shí)現(xiàn)的。（當(dāng)光激活光系統(tǒng)的光反應(yīng)中心時(shí)，通過(guò)一系列的氧化還原反應(yīng)實(shí)現(xiàn)能量的傳遞(前一句中packaging，傳遞

17、能量)。 ）,2020/9/16,In this initial event water molecules are cleaved, oxgen is released, and electrons are donated. 反應(yīng)開(kāi)始時(shí)，水被分解，氧被釋放并提供電子。 These electrons are accepted first by plastiquinone and then by a series of carries as they descend an electron transport chain. 電子沿著電子傳遞鏈,首先傳遞給質(zhì)體醌，然后通過(guò)一系列載體。（電子首先傳

18、遞給質(zhì)體醌，然后通過(guò)一系列載體形成的電子傳遞鏈。 ）,2020/9/16,For each four electrons that pass down the chain, two ATPs are formed. 每傳遞4個(gè)電子，形成2個(gè)ATP。 The last acceptor in the chain is the P700 reaction center of photosystem I. 電子傳遞鏈上的最后一個(gè)受體是光系統(tǒng)的反應(yīng)中心。,2020/9/16,At this point incoming photons boost the energy of the electrons

19、, and they are accepted by ferredoxin. 此處光子激活電子，電子傳遞給鐵氧還蛋白。 Ferredoxin is then reoxidized, and the coenzyme NADP+is reduced to the NADPH. 鐵氧還蛋白再氧化，并且輔酶NADP+還原成NADPH。 The ATP generated previously and the NADPH then take part in the light-independent reactions. 先前（早期）產(chǎn)生的ATP和NADPH進(jìn)入（然后參與）暗反應(yīng)。,2020/9/16

20、,The production of ATP from the transport of electrons excited by light energy down an electron transport chain is termed photophosphorylation. 由電子傳遞鏈偶連（由光激發(fā)的）產(chǎn)生ATP的過(guò)程稱(chēng)為光合磷酸化。,2020/9/16,The one-way flow of electrons through photosystems II and I is called noncyclic photophosphorylation; plants also

21、derive additional ATP through cyclic photophosphorylation, in which some electrons are shunted back through the electron transport chain between photosystem II and I. 通過(guò)光合系統(tǒng)流經(jīng)光合系統(tǒng)的電子路徑稱(chēng)非循環(huán)式光合磷酸化；植物也可以通過(guò)循環(huán)式光合磷酸化獲得額外的ATP，在循環(huán)式光合磷酸化過(guò)程中,一些電子在光系統(tǒng)和之間的電子傳遞鏈中回流。,2020/9/16,2020/9/16,3. The light-independent r

22、eactions: building carbohydrates暗反應(yīng)：碳水化合物的形成,2020/9/16,In the light-independent reactions of photosynthesis, which are driven by ATP and NADPH, CO2 is converted to carbohydrate. 由ATP和NADPH驅(qū)動(dòng)的暗反應(yīng)中，二氧化碳轉(zhuǎn)化成碳水化合物。 The reaction are also known as the Calvin-Benson cycle. 該反應(yīng)也就是卡爾文循環(huán)。,2020/9/16,2020/9/16,A

23、tomspheric CO2 is fixed as it reacts with ribulose biphosphate (RuBP), a reaction that is catalyzed by the enzyme ribulose biphosphate carboxylase. 在二磷酸核酮糖羧化酶催化下,二磷酸核酮糖(RuBP)與空氣中的CO2反應(yīng),從而將二氧化碳固定。,2020/9/16,The reduction of CO2 to carbohydrate is completed via several more steps of the cycle . CO2 被還

24、原成碳水化合物是通過(guò)卡爾文循環(huán)的其它若干反應(yīng)來(lái)實(shí)現(xiàn)的。 Finally, RuBP is regenerated so that the cycle may continue. 最后, RuBP再生,該循環(huán)從而得以繼續(xù)。,2020/9/16,4. Oxygen: An inhibition of photosynthesis氧氣：光合作用的抑制劑,2020/9/16,High levels of oxygen in plant cells can disrupt photosynthesis and can cause photorespiration an inefficient form of the dark reactions in which O2 is fixed rather than CO2 and no carbohyd