2018_Cell-Signalling_STQ_QP

2018 Cell Signalling STQ 2018 / H2 / ACJC PRELIM / P2 Q21Fig. 2.1 shows the activation of a G-protein linked receptor (GPLR) found in the cell surface membrane upon binding of a drug, salbutamol. Salbutamol is often used in the treatment of asthma – a long-term condition which narrows the airways in the lungs. The G protein consists of three subunits - α, β, and γ. Fig. 2.1(a)Describe how GPLR is held within the cell surface membrane.[2] salbutamolGPLRadenyl cyclase dilation of airways ATPcyclic AMPactiveikiAinactiveprotein kinase Ainactiveprotein kinase BactiveproteinkinaseB cell surfaceb

(b)With reference to Fig. 2.1, describe how the use of salbutamol can relieve symptoms of asthma. [4] (c)There are many different types of receptors used by a cell to transduce extracellular signals. Some are located on the cell surface membrane while others are located within the cell. Explain why some receptors are found on the cell surface membrane while others are found within the cell. [2] [Total: 8]

2018 / H2 / DHS PRELIM / P2 Q3Question 2For Examiner’s useMany types of animal cells need to receive chemical signals to survive and grow. Fig. 3 shows how a cell receives Insulin-like Growth Factor 1 (IGF1) and prevents the cell from triggering apoptosis (cell death).ABIGF1 Fig. 3(a)Describe stages A and B shown in Fig. 3. [6]A:

B:For Examiner’s use Scientists have found that the PI 3-kinase and Bad protein of the IGF1 signalling pathway has been mutated in tumour cells. Tumour cells are uncontrolled dividing cells which are resistant to apoptosis.(b)Describe a possible mutation of the following proteins and the corresponding effect of the mutation of the protein's activity in tumour cells. (i)PI 3-kinase [2](ii)Bad protein [2]Total: [10]

2018 / H2 / EJC PRELIM / P2 Q73Fig. 7.1 shows a CREB (cAMP response element binding) signalling pathway. This pathway is triggered when ligand X binds to a receptor at the cell membrane. CREB proteinFig. 7.1(a)With reference to Fig. 7.1, (i)Describe precisely the structure of the G protein coupled receptor and explain how the described structure enables it to perform its function.……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………[2](ii)Describe how protein kinase A (PKA) is activated.

……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… …………………………………………………………………………………………………...[2](iii)State the role of PKA in this signaling pathway? ……………………………………………………………………………………………………… …………………………………………………………………………………………………...[1](b)CREB is an activator protein that binds to its specific control element to upregulate the transcription of the target gene.Explain how a