PhET-Simulations-for-Biology/C3/Membrane-Channels/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Welcome to this spoken tutorial on Membrane Channels PhET simulation. |
| 00:08 | In this tutorial we will, Demonstrate Membrane Channels, PhET simulation. |
| 00:16 | Here I am using Ubuntu Linux OS version 14.04
Java version 1.7.0 |
| 00:29 | Firefox Web Browser version 53.02.2 |
| 00:35 | To follow this tutorial, learner should be familiar with topics in high school biology. |
| 00:43 | Using Membrane Channels simulation, we will learn
To predict movement of particles through the membrane |
| 00:52 | Types of channels present on the membrane |
| 00:56 | To predict the rate of diffusion based on the number and type of channels present |
| 01:03 | About Membrane Channels
Membrane channels are proteins. |
| 01:10 | They allow passive transport of solute across a membrane. |
| 01:15 | The solute moves by simple diffusion through the membrane. |
| 01:20 | Solute moves from the region of higher concentration to the region of lower concentration. |
| 01:27 | The diffusion continues until the two compartments have equal concentrations. |
| 01:34 | Two types of channels are found in membranes, |
| 01:39 | Leakage channels and Gated channels.
Leakage channels are always open. |
| 01:47 | Gated channels open in response to some stimulus. |
| 01:53 | Use the given link to download the simulation. |
| 01:58 | I have already downloaded Membrane Channels simulation to my Downloads folder. |
| 02:05 | To run the simulation, open the terminal.
At the prompt type, cd space Downloads and press Enter. |
| 02:18 | Then type, java space hyphen jar space membrane hyphen channels_en.jar and press Enter. |
| 02:32 | Membrane Channels simulation opens. |
| 02:36 | This is the interface of Membrane Channels simulation. |
| 02:41 | The simulation window has two compartments separated by a membrane. |
| 02:48 | Each compartment has a solute pump.
Each pump has two different types of solute particles. |
| 02:58 | Particles are represented as green circles and blue diamonds. |
| 03:04 | By default green circle is selected in the upper compartment.
Blue diamond is selected in the lower compartment. |
| 03:15 | We can select the particle by clicking on the radio button next to the particle. |
| 03:21 | Click on the red button, to release a single particle into the compartment. |
| 03:27 | Two different kinds of channels are provided at the bottom, |
| 03:32 | Leakage channels and Gated channels.
Drag and drop to add channels on the membrane. |
| 03:43 | Gated channels can be opened and closed using the buttons on the right-pannel. |
| 03:50 | Use the Play/Pause button to start and pause the simulation. |
| 03:56 | Step Button is activated when Play/Pause button is on Play mode.
There is a slider to change the Sim speed from Slow to Fast. |
| 04:08 | There is a check-box on the right panel to show the concentrations of particles.
Click on the Show Concentrations check-box. |
| 04:19 | Bar graphs showing concentrations for each compartment appear on the screen. |
| 04:26 | Click on Clear Particles button, to clear the particles present in the compartment. |
| 04:33 | To reset the simulation, click on Reset All button. |
| 04:38 | A message appears to prompt you to confirm the reset all settings. |
| 04:44 | Click on Yes button. |
| 04:47 | Click on Play button to play the simulation. |
| 04:51 | In the lower compartment, select blue particle. |
| 04:56 | Click on the red button to add blue particles to the compartment. |
| 05:01 | Click the red button 10 times to add 10 blue particles to the compartment. |
| 05:11 | Place 2 blue leakage channels on the membrane.
The blue particles pass through the channel to the upper compartment. |
| 05:22 | Wait for a few seconds.
Note the number of blue particles in the upper compartment. |
| 05:30 | The particles move in both directions through the channels.
The diffusion of the particles continues. |
| 05:39 | After sometime the particles in both the compartments are almost equal.
Click on Pause button to pause the simulation. |
| 05:49 | Click on Show Concentrations check-box. |
| 05:53 | Concentrations of particles in each compartment is represented as a bar graph. |
| 06:00 | Click on Play button to play the simulation. |
| 06:04 | Place one green Leakage Channel on the membrane. |
| 06:09 | Observe that blue particles do not pass through the green channel. |
| 06:15 | Now add 10 green particles to the lower compartment. |
| 06:20 | Click on the radio button next to the green particle. |
| 06:25 | Click the red button 10 times to add 10 green particles. |
| 06:32 | Observe the movement of the particles.
Notice that the green particles do not pass through the blue channels. |
| 06:42 | They pass through the green channel only.
This shows that, the channels are selective. |
| 06:50 | They only allow a particular particle to pass through them. |
| 06:55 | After sometime equilibrium is reached.
Click on Pause button to pause the simulation. |
| 07:03 | Note that at this point concentration of the particles in both the compartments are almost same. |
| 07:11 | Click on Play button.
The particles continue to move in both the directions to maintain the equilibrium. |
| 07:20 | Click on Reset All button.
Click Yes to confirm the reset all settings. |
| 07:27 | Add 20 green particles to the upper compartment by clicking 20 times. |
| 07:37 | In the lower compartment, select blue particles radio button. |
| 07:42 | Add 20 blue particles to the lower compartment. |
| 07:50 | Place one each blue and green gated channel on the membrane. |
| 07:57 | Click on blue Open button on the right panel. |
| 08:01 | On the membrane, blue channel opens. |
| 08:05 | Blue particles move through the Gated channel in both the directions. |
| 08:10 | Click on Show Concentrations check-box.
Wait until equilibrium is reached. |
| 08:19 | Green particles do not pass through the Blue gated channel, hence remain in the upper compartment. |
| 08:28 | Observe that there are no green particles in the lower compartment. |
| 08:34 | Now click on the green Open button on the right panel.
On the membrane, green channel opens. |
| 08:43 | Green particles pass through the green gated channel to the lower compartment. |
| 08:49 | Equilibrium is reached after a few minutes. |
| 08:55 | Next, click on green Close button to close the green gated channel. |
| 09:01 | Observe the movement of particles. Notice that now only blue particles move between the compartments. |
| 09:11 | Green particles do not cross the compartments, as they cannot pass through blue channel. |
| 09:18 | This is how solute or ions diffuse through the membrane in real cells. |
| 09:29 | Lets Summarize, In this tutorial we have learnt,
How to use Membrane Channels, PhET Simulation. |
| 09:38 | We have also learnt, To predict movement of particles through the membrane |
| 09:44 | Types of channels present on the membrane |
| 09:48 | To predict the rate of diffusion based on the number and type of channels present |
| 09:55 | As an assignment
Fill the upper and lower compartments with equal number of blue and green particles. |
| 10:05 | Add gated channels of both colors on the membrane. |
| 10:10 | Note if the diffusion rate increases with increase in number of channels.
Give Explanation. |
| 10:20 | The video at the following link summarizes the Spoken Tutorial project.
Please download and watch it. |
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| 10:48 | This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching. |
| 10:56 | The Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
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| 11:09 | This tutorial is contributed by Snehalatha Kaliappan and Meenal Ghoderao from IIT Bombay.
Thank you for joining. |
