A . Molecules, including signaling molecules always move randomly. - PowerPoint Presentation

1. A. Molecules, including signaling molecules always move randomly. Everything in our cells and in our bodies happens randomly. It is the nature of molecules to randomly move about. So somehow, the cells is a bag of proteins, signals all move about randomly and still very organized behavior results. You can clench your fist and relax your fist … and at the molecular level thousands of signals are randomly flying about.1. Random motion of signals: Regulation of signal concentration.http://youtu.be/8IlxsEzTbxwThese are proteins found in your blood. They are moving about in random directions, due to Brownian motion. Video by Cosmocyte, LLC

2. B. Random motion is called Diffusion. OK, so let’s discuss this randomness for a minute. What does randomness look like? Imagine there is a molecule floating in water. This molecule and all of the water molecules will bounce randomly about. This bouncing, you have heard, is Brownian motion. When a molecule is bouncing around in water or air we call the motion of the molecule, diffusion. The molecule in the water always moves randomly. It diffuses about here and there. http://youtu.be/8IlxsEzTbxwThese are proteins found in your blood. They are moving about in random directions, due to Brownian motion. Video by Cosmocyte, LLC

3. Molecule of somethingAnother molecule of somethingWater moleculesDiffusion is molecules mixing up due to their random motion. If molecules start out uneven, they will eventually become evenly distributed.

4. C. Diffusion that starts at a point creates a concentration gradient. Now imagine that there is a place where the signal is coming from. For example, a bacterium has landed in the cut on your arm. Now some proteins in your blood are reacting to the bacterium and becoming signals. The signal is now being made on the bacterium surface. So we have a source of signal. Each signal moves randomly. Each individual signal molecule diffuses in the water of your blood and connective tissues. 1. Random motion of signals: Regulation of signal concentration.

5. However, random motion from a source always creates a concentration gradient. There will be more of the signal closer to the bacterium where the signal is being made. Farther away from the bacterium the concentration will be lower. This concentration gradient is simply what happens when signal are continuously being made at a source and each molecule diffuses randomly. As you can see, each bacterium has a very predictable concentration gradient around it. 1. Random motion of signals: Regulation of signal concentration.

6. However, random motion from a source always creates a concentration gradient. There will be more of the signal closer to the bacterium where the signal is being made. Farther away from the bacterium the concentration will be lower. This concentration gradient is simply what happens when signal are continuously being made at a source and each molecule diffuses randomly. As you can see, each bacterium has a very predictable concentration gradient around it. 1. Random motion of signals: Regulation of signal concentration.

7. However, random motion from a source always creates a concentration gradient. There will be more of the signal closer to the bacterium where the signal is being made. Farther away from the bacterium the concentration will be lower. This concentration gradient is simply what happens when signal are continuously being made at a source and each molecule diffuses randomly. As you can see, each bacterium has a very predictable concentration gradient around it. 1. Random motion of signals: Regulation of signal concentration.

8. So how does a concentration gradient of randomly moving signals cause a specific action? How do the white blood cells respond to the signal in a specific way? If the concentration of signal is high enough, the receptor will have a binding partner. If the concentration is lower, the receptor will be less likely to have a binding partner. So receptors on the side of the cell that are close to the bacterium are more likely to have bind a signal. 1. Random motion of signals: Regulation of signal concentration.

9. So how does a concentration gradient of randomly moving signals cause a specific action? How do the white blood cells respond to the signal in a specific way? If the concentration of signal is high enough, the receptor will have a binding partner. If the concentration is lower, the receptor will be less likely to have a binding partner. So receptors on the side of the cell that are close to the bacterium are more likely to have bind a signal. 1. Random motion of signals: Regulation of signal concentration.

10. So how does a concentration gradient of randomly moving signals cause a specific action? How do the white blood cells respond to the signal in a specific way? If the concentration of signal is high enough, the receptor will have a binding partner. If the concentration is lower, the receptor will be less likely to have a binding partner. So receptors on the side of the cell that are close to the bacterium are more likely to have bind a signal. 1. Random motion of signals: Regulation of signal concentration.

11. In summary: All molecules move randomly. The random movement of molecules is called Brownian motion. Because molecules are always moving about, they diffuse. This means that various kinds of molecules will mix together. Additionally, molecules that are released from one point will, on average, move away from the point and eventually fill up a given space. A concentration gradient forms when the molecules coming from a source have not yet evenly filled a space. A concentration gradient can be used by White Blood Cells to find their way. A movement receptor that binds a certain signal is more likely to be bound on the source side of the white blood side compared to the other side of the cells. 1. Random motion of signals: Regulation of signal concentration.