Cell Communication & Cell Cycle Reading Guide

Name: ________________________ Period: ________ Unit 4: Cell Communication & Cell Cycle Reading Guide Topics: 1. Cell Communication 2. Signal Transduction 3. Homeostasis and Feedback Loops 4. The Cell Cycle 5. Cell Cycle Regulation and Cancer Annotation Key All students are expected to complete annotations for the readings below. ❖ Pink highlighter → Vocabulary words ❖ Yellow highlighter → Key equations/formulas ❖ Underline → Definitions ❖ Circle→ Unfamiliar words ❖ Star → Key ideas/facts ❖ Write a question mark (?) → Next to anything that is confusing you ❖ Write down notes in the margins → Any questions you have or thoughts/comments you have about what you read Topic #1: Cell Communication What is Cell Communication? Cell communication refers to the processes through which cells can detect and respond to signals in their environment. This communication is crucial for coordinating various functions, including growth, development, and maintaining homeostasis. 1 Name: ________________________ Period: ________ How Do Cells Communicate? Cells communicate through three main types of signaling: direct contact, local signaling, and long-distance signaling. See the table on the next page that depicts these signaling types. 1. Direct Contact ○ Gap Junctions (Animals): Protein channels that connect adjacent cells. They enable the transfer of ions, small molecules, and electrical impulses directly between cells. i. For example, in cardiac muscle cells, gap junctions ensure that the heart contracts in a coordinated manner by allowing ions to flow quickly between cells. ○ Plasmodesmata (Plants): Microscopic channels that traverse the cell walls of plant cells. ○ Juxtacrine Signaling: Involves direct contact between immune cells and their target cells. i. NK cells bind to infected or cancerous cells through receptor-ligand interactions on their surfaces. 2. Local Signaling: ○ Autocrine Signaling: A cell targets itself. i. Cancer cells often use autocrine signaling to stimulate their own growth and proliferation. ○ Paracrine Signaling: A cell targets a nearby cell. i. This type of signaling is often seen in tissue repair and immune responses. ii. Example: growth factors signal nearby target cells to grown and divide ○ Synaptic Signaling: This is a specific type of local signaling used by neurons. i. Neurotransmitters are released from the synaptic terminal of a neuron and diffuse across the synaptic cleft to bind to receptors on the adjacent neuron, muscle cell, or gland, facilitating rapid communication across synapses. 3. Long-Distance Signaling: ○ Hormone Signaling in Plants: Plants use hormones to communicate over long distances through their vascular tissues, such as the phloem and xylem. ○ Endocrine Signaling in Animals: In animals, hormones are released into the bloodstream by endocrine glands and travel to target cells throughout the body. i. An example is insulin, which regulates blood sugar levels by signaling cells to uptake glucose. 2 Name: ________________________ Period: ________ Summary of Cell Signaling Types: 3 Name: ________________________ Period: ________ Topic #2: Signal Transduction Pathways Overview of Cell Signaling Cell signaling is a complex process that allows cells to communicate with each other and respond to their environment. This process is vital for numerous cellular functions, including growth, differentiation, and metabolism. Signal transduction involves three main stages: reception, transduction, and response. 1. Reception Reception is the first stage of cell signaling, where a signaling molecule, known as a ligand, binds to a receptor on the target cell's surface or inside the cell. ● Ligands and Receptors: ○ Ligands: These are signaling molecules that can be proteins, peptides, amino acids, steroids, or other types of molecules. They bind specifically to receptors. ○ Receptors: These are proteins that receive the signaling molecules. They can be located on the plasma membrane or within the cell (intracellular receptors). ● Types of Receptors: ○ Plasma Membrane Receptors: These receptors are embedded in the cell membrane and bind to ligands that cannot cross the membrane. Examples include G protein-coupled receptors (GPCRs) and ion channel receptors. ■ GPCRs: These are a large family of receptors that work with the help of a G protein. When a ligand binds to a GPCR, it causes a conformational change that activates the G protein, starting the signal transduction pathway. 4