Difference between revisions of "PhET-Simulations-for-Biology/C3/Membrane-Channels/English-timed"

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Latest revision as of 18:41, 10 August 2022

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.

10:29 The Spoken Tutorial Project team: conducts workshops using spoken tutorials and gives certificates on passing online tests.

For more details, please write to us.

10:43 Please post your timed queries on this forum.
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.

More information on this Mission is available at this link.

11:09 This tutorial is contributed by Snehalatha Kaliappan and Meenal Ghoderao from IIT Bombay.

Thank you for joining.

Contributors and Content Editors

Nancyvarkey, PoojaMoolya

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