BIO 2 – Cell and Molecular Biology Signaling Pathways PDF

Written Report of Group 7 BIO 2 – Cell and Molecular Biology Signaling Pathways That Control Gene Activity Learning Objectives: At the end of the lesson, students will be able to: o Explain gene activity in simple terms. o Identify key steps in signaling pathways. o Recognize that errors in signal...

Written Report of Group 7 BIO 2 – Cell and Molecular Biology Signaling Pathways That Control Gene Activity Learning Objectives: At the end of the lesson, students will be able to: o Explain gene activity in simple terms. o Identify key steps in signaling pathways. o Recognize that errors in signaling pathways can result in diseases. What is a Cell? Cells are the basic building blocks of all living things. Think of a cell like a tiny factory, working non-stop to keep your body alive and healthy. Inside every cell are tiny machines that perform vital tasks, such as making energy, repairing damage, and growing. What Are Genes? Genes are like instruction manuals inside every cell. They direct the cell on how to build and maintain your body by producing proteins, which are essential for all cellular activities. A gene is the fundamental physical and functional unit of heredity. How Are Cells and Genes Connected? Genes can be compared to a switch. Turning the switch “on” means the gene is active and producing proteins. Turning it “off” means no proteins are made, so specific tasks can’t be performed. Mechanism: Genes are located in the DNA inside the cell’s nucleus. When active, they instruct the cell on how to behave by producing specific proteins. What Are Signaling Pathways? Signaling pathways are communication networks within cells. They allow cells to “talk” to each other and respond to changes in their environment. Connection Between Signaling and Gene Activity Signaling pathways regulate gene activity by sending messages to activate or block specific genes. Function: Signals trigger events that determine which genes are active at any time. This process helps cells grow, repair, or perform other vital functions. Key Players in Signaling Pathways Ligand: The message. A molecule or atom that binds to a receptor protein, causing changes in cell signaling. Receptor: The receiver. A molecule or cell that binds to a specific substance and triggers a reaction. Effector: The response. Molecules or cells that carry out the cellular response to a signal. Relay molecule: Helps the signal move down the pathway. What Happens When Signaling Goes Wrong? Overactive Signals: Can lead to cancer due to excessive cell division. Failed Signals: Can result in conditions like diabetes or other disorders. Possible Causes: A cell doesn’t send a signal at the right time. A signal fails to reach its target. A target cell doesn’t respond to a signal. The Role of Signaling Pathways in Gene Activity Growth Signaling: Regulates growth and development in organisms. Stress Signaling: When cells experience stress (e.g., DNA damage), pathways activate genes for repair or, if the damage is severe, trigger self-destruction. Why Are Signaling Pathways Important? Disruptions in signaling pathways can lead to serious diseases: 1. Cancer: Overactive pathways cause uncontrollable cell division, forming tumors. 2. Diabetes: Failed signaling disrupts glucose regulation. 3. Heart Disease: Impaired signaling affects blood vessel growth and function, leading to conditions like high blood pressure or atherosclerosis. Significance: Signaling pathways are essential for regulating gene activity, ensuring proper cell function, and adapting to challenges. By studying them, we unlock tools to revolutionize medicine and improve health outcomes. PROCESS OF SIGNALING PATHWAYS THAT CONTROLS GENE ACTIVITY SIGNALING PATHWAYS are like intricate communication networks within cells, allowing them to respond to changes in their environment and regulate their activities. CELL SIGNALING it is the ability of a cell to receive process and transmit signals with its environment and with itself. What is the difference between PRIMARY and SECONDARY receptors? PRIMARY - extracellular signaling molecules, originate outside the cell SECONDARY - intracellular signaling molecules, generated INSIDE the cell. 5 Types of Cell Signaling 1. Autocrine: A cell signals itself. 2. Paracrine: A cell signals nearby cells. 3. Juxtacrine: A cell signals a directly contacting cell (physical contact required). 4. Endocrine: A cell signals distant cells via the bloodstream (hormones). 5. Synaptic: A specialized type of paracrine signaling between neurons. PROCESS OF SIGNALING PATHWAYS THAT CONTROLS GENE ACTIVITY Signaling pathways Signaling pathways are a series of chemical reactions that allow cells to communicate with each other and perform their functions. 3 Stages of signaling pathways 1. Reception: The signal molecule binds to a specific receptor on the cell surface. 2. Transduction: The signal is transmitted through a series of relay molecules within the cell. 3. Response: The signal triggers a specific cellular response. Key Types of Signaling Pathways 1. G Protein-Coupled Receptors (GPCRs): The largest family of cell surface receptors. They activate G proteins, which can then activate or inhibit various intracellular effectors. 2. Receptor Tyrosine Kinases (RTKs): These receptors phosphorylate tyrosine residues on themselves and other proteins, leading to activation of signaling cascades. 3. Ion Channel Receptors: These receptors open or close ion channels in response to specific stimuli, altering the electrical potential across the cell membrane. What is signaling payhways?? -are complex networks of interacting molecules within cells that transmit information and coordinate cellular responses to various stimuli. These pathways are essential for regulating cell growth, differentiation, survival, and many other processes. Cell Growth and Proliferation: They regulate the rate of cell division and growth. Cell Differentiation: They control the specialization of cells into different types. Cell Survival: They determine whether a cell lives or dies. What is Misregulating of signaling pathways? refers to disruptions in the normal functioning of these pathways, leading to various cellular malfunctions and diseases. When signaling pathways are disrupted, the consequences can be significant, leading to a variety of cellular dysfunctions and ultimately contributing to disease development. Misregulation can occur due to: Mutations: Changes in the genes encoding signaling proteins can alter their structure or function, leading to aberrant signaling. ex. Sickle Cell Anemia Overexpression or underexpression: Increased or decreased production of signaling proteins can disrupt the balance of the pathway. Ex. HER2 in breast cancer Changes in the cellular environment: Factors like inflammation, oxidative stress, or changes in nutrient availability can influence signaling pathway activity. Cancer is a group of diseases characterized by uncontrolled cell growth and the ability to invade other tissues or spread throughout the body. This abnormal growth is caused from disruptions in signaling pathways that govern critical cellular processes, such as gene activity, cell division, and programmed cell death (apoptosis). Benign tumors These tumors are noncancerous and grow slowly, usually staying in one place and not spreading to other parts of the body. Malignant tumors These tumors are cancerous and have cells that grow uncontrollably and spread to other parts of the body. They can spread through the blood and lymph systems. Malignant tumors usually grow rapidly. Key Signaling Pathways in Cancer 1. Growth Factor Pathways: These pathways are responsible for stimulating cell growth. They are activated by growth factors, proteins that bind to specific receptors on the cell surface, triggering a cascade of events within the cell. Ras genes, crucial components of these pathways, transmits signals that promote cell proliferation ( Cell proliferation is the process by which cells grow and divide to create two new cells, which is a key mechanism for tissue growth). Mutations in Ras genes can lead to its constant activation, driving uncontrolled cell growth that can lead to cancer. Another key player is PTEN, a tumor suppressor gene that negatively regulates these pathways. When PTEN is faulty, it fails to restrain cell growth, leading to cancer development. 2. Wnt/β-Catenin Pathway This pathway controls gene transcription related to cell growth. Mutations in key components, such as tumor suppressor APC, cause uncontrolled activity of the Wnt pathway, contributing to tumor formation. The APC protein keeps cells from growing and dividing too fast. It helps control how often a cell divides, how it attaches to other cells within a tissue, and whether a cell moves within or away from a tissue. 3. Hedgehog Signaling Pathway Hedgehog signaling is crucial for embryonic development and tissue repair. When this pathway is abnormally activated—often through mutations in PTCH1 —it can lead to cancers like basal cell carcinoma and medulloblastoma. The PTCH1 gene is a tumor suppressor gene that regulates cell growth and division: Mutations in the PTCH1 gene can cause cells to grow and divide abnormally, which can lead to cancer. 4. Notch Pathway The Notch pathway determines cell fate. Abnormal activity, such as mutations in Notch receptors or overexpression of their ligands, contributes to cancers like leukemia and certain solid tumors. 5. Tumor Suppressor Pathways p53 Pathway: Known as the “guardian of the genome,” p53 detects DNA damage and either halts cell division or induces apoptosis. TP53 is a gene that provides instructions for making the protein p53, which is a tumor suppressor TP53 gene mutations occur in over half of all cancers, allowing cells with genetic errors to continue dividing. RB Pathway: The RB protein regulates the cell cycle. When RB function is lost, it leads to uncontrolled cell division, a key feature of cancer. Mechanisms of Pathway Dysregulation in Cancer 1. Mutations Mutations in pathway-related genes can: Activate oncogenes (e.g., Ras). Inactivate tumor suppressors (e.g., p53). 2. Epigenetic Changes The main point is that chemical modifications to DNA (epigenetic changes) can alter gene expression, leading to cancer. These changes don't alter the DNA sequence itself, but they affect how genes are "read" by the cell. This can silence tumor suppressor genes (genes that normally prevent cancer) or activate oncogenes (genes that promote cancer growth). 3. Gene Amplifications and Translocations Gene amplification involves an increase in the number of copies of a specific gene, while gene fusion involves the joining of two different genes. Both processes lead to an overproduction of proteins that stimulate cell growth and division, contributing to cancer development. 4. Microenvironmental Influences Tumor cells are influenced by their surroundings, including inflammatory cytokines, growth factors, and hypoxia, which sustain abnormal signaling