2018_Cancer_STQ_QP

2018 Cancer STQ 2018 / H2 / AJC PRELIM / P2 Q51Skin cancer cells may be grown in culture and examined using the technique of immunofluorescence in which antibodies are used to attach fluorescent dyes to specific molecules within the cells. Fig. 5.1 is an immunofluorescent light micrograph of skin cancer cells. A particular type of protein is stained with the dye and appears as pale regions in the skin cancer cells. Fig. 5.1 (a)(i)Before the skin cancer cells could be stained with antibodies, the cells had to be fixed and treated with a mild detergent to increase the permeability of the cell surface membranes.Explain the purpose of this step.………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………[2](ii)There are two cells in the process of dividing. Each of these cells has two areas stained heavily, labelled A on Fig. 5.1.Suggest the identity of these two areas and outline their functions in these cells.…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………[3]

(iii)Suggest why the proteins stained in the cytoplasm of the non-dividing cells in Fig. 5.1 are not evenly distributed.……………………………………………………………………………………………………………………………………………………………………………………[1](b)Explain two ways in which the behaviour of chromosomes in prophase of meiosis I differ from prophase of mitosis. ……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….[2](c)Some chemicals known to inhibit the cell cycle are used as drugs for the treatment of cancer. A particular drug was found to be most effective when applied to cancer cells in the G2 phase of the cell cycle. Suggest the possible mechanism of this drug. ……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….[3][Total: 11]

2018 / H2 / MJC PRELIM / P2 Q5QUESTION 2Fig. 5.1 shows the stages involved in the synthesis of a p53 protein in a eukaryotic cell. Fig. 5.1(a)Name the structure H. [1]……………………………………………………………………………………………………………..(b)Outline the events that occur in the nucleus of the cell to produce a functional molecule of mRNA encoding a p53 protein. [4]……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..

In a particular defective cell, all the pre-mRNA encoding the p53 protein were not cut.(i)Explain how this would affect the function of the p53 protein. [4]………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………