CELL SIGNALLING

1 EJC H2 Biology T2W4 Cell Signalling Cell Signalling 1. Introduction The study of cell communication focuses on how a cell gives and receives messages with its environment and with itself. Cells do not live in isolation. In fact, their survival hinges on receiving and processing information from the external environment. In multicellular organisms, cell communication takes the form of cell signalling. Cell signalling is the fundamental process by which specific information is transferred from the cell surface to the cytosol and ultimately to the nucleus, leading to changes in gene expression. As such, cell signalling allows for specialisation of groups of cells. Multiple cell types can then join together to form tissues such as muscle, blood, and brain tissue. Disruption of cell signalling processes can have significant i mpacts on cell physiology. Alteration of cell signalling by neurotoxicants may be linked to transient functional impairment or to long -term changes, resulting in permanent behavioural impairments. 2. Learning Outcomes 3 (m) Outline the main stages of cell signaling: i. Ligand-receptor interaction ii. Signal transduction (phosphorylation cascade and signal amplification) iii. Cellular response (change in gene expression) (Knowledge of intracellular receptors is not required) 3 (n) Explain the roles and nature of second messengers (including cyclic AMP) 3 (o) Explain the role of kinases and phosphatases in signal amplification. 3 (p) Outline how insulin and glucagon regulate the concentration of blood glucose through the respective tyrosine kinase receptor and G-protein linked receptor. (The outline should be limited to describing how the ligand induces a conformational change in a membrane-bound receptor to trigger downstream signalling pathways that elicit physiological changes in blood glucose concentration. Details of different second messengers and specific kinases activated in the pathway are not required.) Students should be able to use the knowledge gained in this section in new situations or to solve related problems.

2 EJC H2 Biology T2W4 Cell Signalling 3. References  Campbell, N.A. and Reece, J.B. (2008). Biology, 8th edition. Pearson.  Sherwood, Fundamental of Human Physiology, 4th edition  Brooker et al., Biology, McGraw-Hill  Ho YK (2003) A-level course in Biology – Core syllabus, Longman 4. Organisation of Lecture Content Introduction 1 2. Learning Outcomes 1 3. References 2 4. Organisation of Lecture Content 3 5. Overview of Cell Signalling 3 A. Types of Cell Communication 3 B. Overview of the Stages of Cell Signalling 3 6. Mechanisms of Cell Signalling 5 I. STAGE 1: Ligand- Receptor Interaction (RECEPTION) 5 II. STAGE 2: Signal Transduction (TRANSDUCTION) 7 1. Phosphorylation Cascade 7 2. Signal Amplification 9 III. STAGE 3: Cellular Response (RESPONSE) 11 7. Types of Receptors 13 1. G-protein-coupled Rece