Cell Communication Learning Objectives, Enduring Understandings, and Essential Knowledge

Introduction

As with the rest of my curriculum, I’ve gone through the College Board’s Course and Exam Description for AP Biology and extracted the following learning objectives, Enduring Understandings, and pieces of essential knowledge. This is what I’m using to inform the development of my on-line tutorials about cell communication, and the instruction I’m delivering to my own students at BHS. I’d love to know what you think.

Learning Objectives

  1. LO 3.31: The student is able to describe basic chemical processes for cell communication shared across evolutionary lines of descent  (EK: 3D1)
  2. LO 3.32:The student is able to generate scientific questions involving cell communication as it relates to the process of evolution (EK: 3D1)  
  3. LO 3.33:The student is able to use representation(s) and appropriate models to describe features of a cell signaling pathway  (EK: 3D1)
  4. LO 3.34:The student is able to construct explanations of cell communication through cell-to-cell direct contact or through chemical signaling  (EK: 3D2)
  5. LO 3.35:The student is able to create representations that depict how cell-to-cell communication occurs by direct contact or from a distance through chemical signaling (EK: 3D2)
  6. LO 3.36:The student is able to describe a model that expresses the key elements of signal transduction pathways by which a signal is converted to a cellular response  (EK: 3D3)
  7. LO 3.37:The student is able to justify claims based on scientific evidence that changes in signal transduction pathways can alter cellular response  (EK: 3D4)
  8. LO 3.38:The student is able to describe a model that expresses key elements to show how change in signal transduction can alter cellular response.  (EK: 3D4)
  9. LO 3.39:The student is able to construct an explanation of how certain drugs affect signal reception and, consequently, signal transduction pathways  (EK: 3D4)

Enduring Understandings and Essential Knowledge (3.D.)

  1. Key question: how do cells know what to do and when to do it? Communication is about transduction of signals that can be inhibitory or stimulatory. These can come from other cells, or the environment (including the living environment)
  2. Signal transduction is under strong selective pressure
  3. For unicellular creatures, this is how response to the environment occurs.
    1. IE: quorum sensing, pheromones
  4. For multicellular organisms, transduction coordinates cell activities, and can regulate the entire organism.  (3.D.1.d)
    1. IE: epinephrine leading to glycogen breakdown
    2. Temperature determining sex in reptiles
  5. Cells communicate with each other through direct contact with other cells  (such as in the immune system, or plasmodesmata in plants) , or from a distance through chemical signaling (3.D.2)
  6. Process of cell communication (3.D.3)
    1. Signal production (which can be molecular). Note that the signal can also be environmental (physical, chemical, etc.)
    2. Recognition of a ligand by a receptor protein. Note that the response is often graded, with required threshold concentrations
    3. Ligands can be peptides, other small molecules, or proteins. Receptor-ligand relationship is one-to-one
    4. Binding with the ligand causes receptor’s shape to change, initiating transduction
      1. IE: G-protein linked receptors
      2. IE: Ligand-gated ion channels
      3. IE: Receptor tyrosine kinases
    5. Transduction converts the signal to a cellular response
      1. Signalling cascades relay signals from the receptor to a target within the cell, often with amplification of the the incoming signal, generating cellular responses.
      2. Second messengers are often involved
        1. IEs: ligand gated ion channels, cyclic AMP, Ca++, IP3
      3. Typical transduction pathways result in
        1. Protein modifications, phosphorylation cascades
        2. Changes in gene expression
        3. Apoptosis
        4. Change is physiological state, enzyme activity
  7. Changes in signal transduction pathways alter cellular response (3.D.4)
    1. IE: diabetes, cancer, cholera (see 3.D.4)
    2. IE: drug such as hypertensives, anesthetics, birth control drugs
  8. Understanding of signalling pathways has allowed for manipulation of these pathways:
    1. IE: birth control pills
    2. IE: fruit ripening control
    3. IE: antidepressants, control of blood pressure, etc.

Link to Module 11: Cell Communication