THEME THEME Standard/ Learning Objectives Language Development Unit 4: Cell Communication and Cell Cycle 4.1: Cell Communication ENGAGE 4.2: Introduction to Signal transduction EXPLORE EXPRESS EVALUATE NEXT STEPS THEME THEME Standard/ Learning Objectives Language Development ENGAGE Genetic Diversity and Adaptation in UAE's Ecosystems. Central Idea/Big Question: In what ways do cells use energy to communicate with one another? Competencies Problem Solving, Digital Competency, Critical thinking EXPLORE EXPRESS Values Resilience, Respect EVALUATE NEXT STEPS Approaches to Learning Research Skills THEME THEME Standard/ Learning Objectives Language Development Curriculum Standard(s) IST-3, ENE-3, IST-1 ENGAGE EXPLORE EXPRESS Learning Objectives: ❖ I can Explain how cells communicate with one another through direct contact or chemical signaling mechanisms ❖ I can explain the types of cell communication EVALUATE NEXT STEPS ❖ I can Describe the main components of a signal transduction pathway. THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Language Development ❖ Chromatin ❖ Chromosome ❖ Nucleosome ❖ Cell cycle ❖ Interphase ❖ Mitosis ❖ Prophase ❖ Transduction ❖ Centromere ❖ Spindle apparatus ❖ Ligand ❖ Direct Contact ❖ Cell Surface Receptors ❖ G-protein-coupled receptors THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Think-Pair-Share ❖ Imagine you're a cell in the body, surrounded by trillions of others. ❖ To keep everything running smoothly—like digesting food or responding to danger, you need to send and receive messages quickly and accurately. ❖ But what happens if those messages get mixed up or lost? Let’s find out! THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Explore Refer to your slides or Online Inspire Biology BookiPad 1.How can cells communicate? 2. How do cells communicate with other cells over short distances? 3.How do cells communicate with other cells over long distances? 4.How is the process of distance communication different from the process of communicating during cell-cell contact? THEME THEME Standard/ Learning Objectives Cell Communication Language Development ❖ Cell communication is the key to coordinating activities in multicellular organisms. It involves direct contact, local signaling, and long-distance messaging through hormones. These processes help maintain homeostasis and regulate vital functions. ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS ❖ Cells use ligands and receptors to send and receive signals. This triggers intracellular pathways that amplify the message, leading to specific responses. ❖ Understanding these mechanisms is crucial for developing treatments for diseases caused by faulty cell communication. THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Cell to Cell -Communication Types Direct contact signaling: ❖ Cells communicate through direct contact (juxtacrine signaling) via interactions between molecules on the surfaces of adjacent cells or between cells and the extracellular matrix ▪ Gap junctions between animal cells allow for rapid transmission of signals in the form of small molecules or ions between cells (calcium ions, cyclic AMP) ▪ Plasmodesmata between plant cells allow for the transmission of signaling molecules, proteins, and RNA between cells (transcription factors, small RNAs) THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Cell to Cell -Communication Types Direct Signaling Across Gap Junctions (Juxtacrine) ❖ Gap junctions in animals and plasmodesmata in plants are connections between the plasma membranes of neighboring cells. ❖ These water-filled channels allow small signaling molecules, called intracellular mediators, to diffuse between the two cells. Small molecules, such as calcium ions (Ca2+), are able to move between cells, but large molecules, like proteins and DNA, cannot fit through the channels. ❖ The specificity of the channels ensures that the cells remain independent, but can quickly and easily transmit signals. ❖ The transfer of signaling molecules communicates the current state of the cell that is directly next to the target cell; this allows a group of cells to coordinate their response to a signal that only one of them may have received. In plants, plasmodesmata are ubiquitous, making the entire plant into a giant communication network. THEME THEME Standard/ Learning Objectives Cell to Cell -Communication Types Direct contact signaling: (juxtacrine) Language ❖ consider one of your body's most important cell communication Development pathways – the pathway that allows your immune cells to recognize and kill invading pathogens like viruses and bacteria. Almost all parts of your immune system – from the white blood ENGAGE cells that catch and kill invading bacteria to the cells that build and release antibodies to fight infections – rely on cellto-cell contact signal transduction pathways to carry out their EXPLORE work. ❖ different cells can react to encountering another cell in different ways. EXPRESS example, Helper T-cells learn what the antigen of an invading virus or bacteria looks like when trained by a phagocytic antigenEVALUATE presenting cell. Then, through another cell-to-cell contact, helper T-cells can “train” B-cells, which then produce the antibodies an organism NEXT STEPS needs to fight off an infection! THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Local Signaling Paracrine signals ❖ Signals that act locally between cells that are close together are called paracrine signals. ❖ Paracrine signals move by diffusion through the extracellular matrix. These types of signals usually elicit quick responses that last only a short amount of time. In order to keep the response localized, paracrine ligand molecules are normally quickly degraded by enzymes or removed by neighboring cells. ❖ Removing the signals will reestablish the concentration gradient for the signal, allowing them to quickly diffuse through the intracellular space if released again. THEME THEME Standard/ Learning Objectives Paracrine signals (Neuronal Signaling): Local Signaling Language ❖ One example of paracrine signaling is the transfer of signals Development across synapses between nerve cells. ❖ A nerve cell consists of a cell body, several short, branched extensions ENGAGE called dendrites that receive stimuli, and a long extension called an axon, which transmits signals to other nerve cells or muscle cells. The junction between nerve cells where signal transmission occurs is called a synapse. ❖ EXPLORE A synaptic signal is a chemical signal that travels between nerve cells. Signals within the nerve cells are propagated by fastmoving electrical impulses. When these impulses reach the end of the axon, the signal continues on to a dendrite of the next EXPRESS cell by the release of chemical ligands called neurotransmitters by the presynaptic cell (the cell emitting the signal). ❖ The neurotransmitters are transported across the very small EVALUATE distances between nerve cells, which are called chemical synapses. ❖ The small distance between nerve cells allows the signal to NEXT travelSTEPS quickly; this enables an immediate response. THEME THEME Standard/ Learning Objectives Autocrine Signaling: Language Local Signaling ❖ Autocrine signals are produced by signaling cells that can also bind to Development the ligand that is released. ❖ This means the signaling cell and the target cell can be the same or a similar cell (the prefix auto- means self, a reminder that the signaling ENGAGE cell sends a signal to itself). ❖ This type of signaling often occurs during the early development of an organism to ensure that cells develop into the correct tissues and take EXPLORE on the proper function. ❖ Autocrine signaling also regulates pain sensation and inflammatory responses. Further, if a cell is infected with a virus, the cell can signal EXPRESS itself to undergo programmed cell death, killing the virus in the process. ❖ In some cases, neighboring cells of the same type are also influenced by the released ligand. EVALUATE ❖ In embryological development, this process of stimulating a group of neighboring cells may help to direct the differentiation of identical cells into the same cell type, thus ensuring the proper developmental NEXT STEPS outcome. THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Long-distance signaling (endocrine signals) ❖ Signals from distant cells are called endocrine signals, and they originate from endocrine cells. (In the body, many endocrine cells are located in endocrine glands, such as the thyroid gland, the hypothalamus, and the pituitary gland.) These types of signals usually produce a slower response but have a longerlasting effect. The ligands released in endocrine signaling are called hormones, signaling molecules that are produced in one part of the body but affect other body regions some distance away. ❖ Hormones travel the large distances between endocrine cells and their target cells via the bloodstream, which is a relatively slow way to move throughout the body. Because of their form of transport, hormones become diluted and are present in low concentrations when they act on their target cells. This is different from paracrine signaling, in which local concentrations of ligands can be very high. ❖ Hormones target cells that are programmed to respond to specific hormones (insulin targets liver and muscle cells) ❖ Enables coordination of physiological processes across multiple organs and systems (growth, reproduction, metabolism) THEME THEME ❖ How does The pancreas regulate the body’s blood glucose levels? Standard/ ❖ When blood glucose levels are high, glucose importers move glucose into beta cells Learning Objectives within the pancreas. ❖ This activates a signal transduction pathway that causes insulin to be excreted from the beta cells. Language ❖ The insulin travels through the blood, where it binds to insulin receptor proteins in Development cells across the body. ❖ When insulin binds to liver cells, it transduces a signal that causes the liver to store glucose as glycogen. ENGAGE ❖ When insulin binds to receptors on other tissues throughout your body, the receptors start a series of reactions that cause vesicles loaded with glucose importers to bind to the cell membrane. This causes loads of glucose to be imported into each cell from the bloodstream. EXPLORE ❖ when your glucose levels start to drop in your bloodstream, your pancreas secretes glucagon. ❖ This hormone is specific to receptors on liver cells and directs the liver to convert glycogen back into glucose. EXPRESS ❖ This helps regulate your blood glucose levels until you eat your next meal. ❖ Keep in mind that all of these complex forms of cell communication between multiple organ systems and tissues are required just to maintain your blood glucose levels in a specific range. EVALUATE ❖ Your endocrine system is constantly secreting hormones for many different purposes that cause a huge variety of reactions in different cell types around your body. NEXT STEPS THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS The main stages of cell signaling 1- Reception 2- transduction 3- Response THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Introduction to Signal transduction Reception: target cell’s detection of a signaling molecule from outside the cell Ligand (signals): signaling molecule that specifically binds to another molecule Receptor: protein in or on the target cell detects and binds to the ligand, activating and changing shapes Transduction: a series of steps that converts a signal to a form that carries out a specific response, involves a signal transduction pathway Response: any cellular activity triggered by a transduced signal THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Introduction to Signal transduction A ligand must bind to a receptor in order to start transduction (ligands bind to one specific receptor) - The most well-known type of cell receptor called: 1- G- protein-coupled receptor (GPCR) Common cell surface receptor that works with the help of G-proteins THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Introduction to Signal transduction - The most well-known type of cell receptor called: 2- ligand-gated ion channel receptor, a receptor that acts as a gate for ions when a ligand binds THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Introduction to Signal transduction 3- Intracellular receptor: found in the nucleus or cytoplasm of target cells, plays a role in gene transcription THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Transduction Transduction usually involves multiple steps and many molecules can amplify a signal and provide opportunities for control. Responses Could include growth, secretion, gene expression, or apoptosis (programmed cell death) THEME THEME Standard/ Learning Objectives Language Development ● Signals are transduced and ● ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS ● ● ● amplified through phosphorylation (regulates protein activity) Phosphorylation can activate a protein, by protein kinases enzymes that transfer phosphates from ATP to a protein Phosphorylation cascade: a transduction pathway containing at least two protein kinases Cells have a wide variety of protein kinases for various regulations Protein phosphatase: an enzyme that removes phosphate group (deactivates proteins) THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS ● Second messenger: small nonprotein, water-soluble molecule/ ion involved in many signaling pathways Example: Cyclic AMP (cAMP) common second messenger derived from ATP, can broadcast a signal in cytoplasm THEME THEME Express Standard/ Learning Objectives Language Development ENGAGE ❖How are the effects of paracrine signaling limited to an area near the signaling cells? EXPLORE EXPRESS EVALUATE NEXT STEPS ❖What is the primary purpose of cell signaling in organisms? THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS Evaluate THEME THEME Standard/ Learning Objectives Language Development ENGAGE EXPLORE EXPRESS EVALUATE NEXT STEPS
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