Serial Dilution Quesiton and Answer #2 - YouTube
YouTube
Primary Language: English
Description:
My Recent Work
You did not do any work on this video
Subtitles in: English
Start End Subtitles
00:00:01 00:00:02 >> Instructor: This stream cast is created to
00:00:02 00:00:06 show you how to solve this dilution schedule problem.
00:00:06 00:00:09 Preparing a dilution schedule for spread plates
00:00:09 00:00:11 using 10 to the minus two dilutions,
00:00:11 00:00:13 and starting with a culture of E.coli
00:00:13 00:00:16 three point three times 10 to the eight
00:00:16 00:00:18 cells per milliliter.
00:00:18 00:00:21 First thing we need to do is pull the information
00:00:21 00:00:23 we can out of the wording in the question.
00:00:23 00:00:26 So the first we need to know rest for spread plates,
00:00:26 00:00:31 our plate counting range is gonna be between 20 and 200.
00:00:32 00:00:34 Because it's spread plates we're only allowed to
00:00:34 00:00:37 plate zero point one mil of our dilutions
00:00:37 00:00:39 into the petri dishes.
00:00:39 00:00:42 This means the dilution in the petri dish
00:00:42 00:00:45 is gonna come from a tube that is has a dilution
00:00:45 00:00:48 that is one number lower than the dilution
00:00:48 00:00:50 we want in the plate.
00:00:50 00:00:52 So we're gonna figure out
00:00:52 00:00:55 what our target and our bracket dilutions are.
00:00:55 00:00:57 By doing this we figured out that we're going
00:00:57 00:00:59 to need two plate, 10 to the minus six,
00:00:59 00:01:02 10 to the minus seven, and 10 to the minus eight,
00:01:02 00:01:04 to get our targets in our brackets.
00:01:04 00:01:07 Let's draw out our tubes that we have here.
00:01:07 00:01:09 So we have our culture.
00:01:09 00:01:10 We're gonna do as many
00:01:10 00:01:13 10 to the minus two dilutions as possible.
00:01:13 00:01:15 So we're gonna start with point one mil
00:01:15 00:01:16 into nine point nine.
00:01:16 00:01:19 That'll give us our 10 to the minus two dilution.
00:01:19 00:01:21 Point one mil in nine point nine
00:01:21 00:01:25 will give us our 10 to the minus four dilution.
00:01:25 00:01:28 But going forward we need to change our dilution schedules.
00:01:28 00:01:32 If we look at our targets we need a minus eight dilution,
00:01:32 00:01:35 minus seven dilution, and a minus six dilution.
00:01:35 00:01:38 Those have to come from tubes that are one dilution lower.
00:01:38 00:01:40 So we need to create dilutions that are
00:01:40 00:01:44 10 to the minus five, minus six, and minus seven.
00:01:44 00:01:47 Those can't be created with using only
00:01:47 00:01:48 10 to the minus two dilutions.
00:01:48 00:01:50 So we need two dilutions that are gonna have
00:01:50 00:01:55 one mil into nine creating a 10 to minus one dilution.
00:01:55 00:01:58 So we write our dilutions in our cell count so we can see.
00:01:58 00:02:01 We're gonna make 10 to the minus two, 10 to the minus four,
00:02:01 00:02:04 10 to the minus five, six, and seven,
00:02:04 00:02:05 are going to be created there,
00:02:05 00:02:07 so that we have the dilutions we need
00:02:07 00:02:10 to get onto the plates that we have.
00:02:10 00:02:13 Our dilution plates will be written up this way.
00:02:13 00:02:15 Our bracket plate of 10 to the minus six
00:02:15 00:02:18 will have 330 colonies.
00:02:18 00:02:20 Our target plate of 10 to the minus seven
00:02:20 00:02:22 will have 33 colonies.
00:02:22 00:02:25 And our last bracket plate with 10 to the eight dilution
00:02:25 00:02:27 will have three point three colonies.
00:02:27 00:02:29 Because we can only plate zero point one mil,
00:02:29 00:02:32 we can draw that on now.
00:02:32 00:02:35 Our 10 to the minus eight plate is
00:02:35 00:02:38 taking a sample out of our 10 to them minus seven tube.
00:02:38 00:02:41 Our 10 to the seven, minus seven, plate comes from
00:02:41 00:02:43 our 10 to the minus six tube.
00:02:43 00:02:46 And 10 to the minus six plate comes from a
00:02:46 00:02:49 10 to the minus 5 tube, always one dilution lower.
00:02:49 00:02:51 And this would be the correct solution.
Embed
Copy and paste the embed code above
Share
Copy and paste the embed code above