Modes of Cell Communication: Introduction

by Georgina Cornwall, PhD

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    00:01 In this lecture, we will be exploring cell communication. You have to think how does a cell know exactly what it needs to do. It's sort of like being in a very crowded room in which there are hundreds of people talking quite loudly and you're talking to one or two people.

    00:21 How do you separate out the signals from all the people in the room to just those couple of people.

    00:27 Cells have to deal with this and the way that they do is by what sort of receptor proteins they display, and what sort of signals they actually listen to. You don't have to listen to everything at the same time. You can listen to just the conversation that you're involved in.

    00:42 And so this is how cells manage their communications also. In this series of two lectures on cell communication, we'll first explore the five mechanisms that we see cells using to communicate with each other. These depend on whether they are close together or whether they are farther away. Then we will explain the purpose of phosphorylation of different proteins. So adding phosphate or energy to different proteins in order to have the pathways proceed. And then finally, we will compare intracellular and cell surface receptors. So moving forward into the first step of our lecture, we need to think about how cells actually are capable of communicating with each other. We have a few different possible mechanisms but basically they all involve a receptor and a ligand. There are two primary mechanisms that cells can use to signal each other and that depends on whether we are dealing with hydrophobic or hydrophilic ligands or signal molecules. In the case of hydrophobic molecules, we can pass straight through the membrane. Recall the phospholipid bilayer has a large hydrophobic region and thus it's going to exclude any hydrophilic molecules. So hydrophilic molecules will need to signal a receptor from the outside of the cell unless of course there is a channel for them to pass into the cell. But in general it will signal from the outside of the cell whereas hydrophobic molecules are able to pass through the membrane. Things like cholesterol, testosterone, oestrogen, are steroids and can pass straight through the cell membrane and work on an intracellular receptor. We'll examine the details of these receptors later.

    02:39 But once those receptors have been activated, they can then work by activating a whole signal transduction pathway. And that signal transduction pathway, again there is going to be a lot of details that we'll explore. But they end up eliciting some sort of cellular response.

    02:57 So in general there are two means of signalling. Either cell membrane receptors or intracellular receptors.

    About the Lecture

    The lecture Modes of Cell Communication: Introduction by Georgina Cornwall, PhD is from the course Cellular Structure.

    Included Quiz Questions

    1. Intracellular receptors and cell membrane receptors
    2. Phospholipids and peripheral or transmembrane protein molecules
    3. Cholesterol and Steroid molecules
    4. Hydrophilic and hydrophobic cell membrane proteins
    5. Hydrophilic head and hydrophobic tails of cell membrane phospholipids
    1. The hydrophilic molecules diffuse at faster rates through the cell membrane and hence are more efficient signal molecules than hydrophobic molecules.
    2. The communication signals between two cells are passed via hydrophobic or hydrophilic signal molecules.
    3. Due to their hydrophobic nature, the cholesterol based steroid hormones (sex hormones) diffuse across the cell membrane and bind to intracellular receptors to bring a cellular response.
    4. The activated signal specific receptors in a cell lead to the activation of whole signal transduction pathway to bring about the cellular response.
    5. Signal specific receptors get activated after interactions with the signal molecules.

    Author of lecture Modes of Cell Communication: Introduction

     Georgina Cornwall, PhD

    Georgina Cornwall, PhD

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