4. 多細胞生物的個體由受精卵經過多次有絲分裂而形成,但是在正常發育的同時,生物體體內也有許多細胞透過特定的途徑走向滅亡,這個過程稱為計畫性細胞死亡(programmed cell death)。計畫性細胞死亡的類型很多,其中細胞凋亡(apoptosis)是最早被發現也是研究的最透澈的一種。細胞凋亡的過程可以由細胞內部(intrinsic)的訊號起始,也可以由細胞外(extrinsic)的訊息誘發。請分別說明由細胞內起始的細胞凋亡與由細胞外訊息誘發的細胞凋亡的機制。(答案中,請將以下蛋白質:Apaf-1、Bak、Bax、Bcl-2、caspase-8、caspase-9、cell death receptor、cytochrome c及TNF涵括在適宜的機制內。)
3. 歷經幾億年的演化後,真核生物的細胞質中具有多樣的膜狀胞器(membranous organelles),這些膜狀胞器各自具備其特有的組成物質與執行特定功能,然而就整體細胞生理運作而言,這些胞器間也需要在精準的控制下傳遞物質,例如內分泌細胞所釋出的胰島素(insulin)在粗糙內質網(rER, rough endoplasmic reticulum)合成,在高基氏體(the Golgi apparatus)中進行糖化修飾,最終經由分泌小泡(secretory vesicle)完成分泌作用。膜狀胞器間的物質傳遞受到許多分子調控,請說明 Rab、tethering protein、v-SNARE、t-SNARE及NSF如何控制不同膜狀胞器間的辨識與運輸過程。
2. 真核細胞有三種細胞骨架(cytoskeleton)結構,其組成與特性雖然各不相同,但是細胞藉由精巧的控制這些構造完成許多複雜的生理作用。以動物細胞的有絲分裂(mitosis)為例,請說明細胞分裂後期(anaphase)階段,複製後的染色體(sister chromatids)如何經由細胞骨架分離至細胞兩側;在細胞質分裂(cytokinesis)時期,細胞骨架又如何促成細胞分割成兩個獨立的子細胞。
16. A galvanic cell is made based on the following reaction: 2 Al(s) + Cr2O72 (aq) + 14 H+ (aq) → 2 Al3+ (aq) + 2 Cr3+ (aq) + 7 H2O (1) With relevant half reactions: Al3+ (aq) + 3e → Al (s) Eº = -1.66 V Cr2O72 (aq) + 14 H+ (aq) + 6e¯ → 2 Cr3+ (aq) +7 H2O (1) Eº = 1.33 V If [Cr³+] = 0.10 M, [Al3+] = 0.10 M, [Cr2O72] = 1.00 M, and Ecell = 3.02 V at 298 K, what is the pH of the cathode compartment?
15. Radium-226 is a radioactive isotope that decays to form Radon-222 and an alpha particl(E) This process follows first-order kinetics, and the half-life of Radium-226 is 1600 years. Given a sample of 5.00 g of Radium-226, how many moles of Radon-222 would be present in the sample after two years?
14. Ascorbic acid (H2C6H6O6) is a diprotic acid with Ka1 = 7.9 × 10-5 and Ka2 = 1.6 × 10-12 (A) What is the pH of a solution of 350.0 mg ascorbic acid in 500.0 mL water? Show your calculations. (5 pts) (B) Suppose 150.0 mL of 0.01000 M NaOH (aq) was added to the solution from (A). What would the pH of the resulting solution be? Show your calculations.