Thank you so much!! This video helped me a lot. My TAs are so confused and confusing. They always do mistakes, some of which are intolerable!!! Last experiment was about cellular fractionation, and they used 8000 g by mistake instead of the written 800g in the manual as the first centrifugation. About 95% of our experiments have failed. They even failed to do Gram staining properly. Let alone their broken English and intolerance to students' questions. They almost rarely understand the questions asked anyway, and even if they understand the question they most probably give very misleading and very wrong answers. I'm so jealous to know that some students have such good professors and TAs. Good lock guys and please appreciate what you have!
Great video! Have to do something similar and write it up as part of a biology SKE but don't have chance to see the experiment live. This is a massive help and really well explained. Bit of an abrupt ending though...
4:09 Why does centrifuging at high speeds cause chloroplasts to sediment as pellets? I thought they were part of the supernatant since they're lighter in mass and thus less dense
Shak Pherze it depends how fast you spin them. Usually you would spin slowly to remove debris if cell walls leaving the chloroplasts in the supernatant then spin the supernatant again to obtain a pellet containing chloroplast which you can then resuspend in buffer to obtain fairly pure chloroplasts. To be honest those little school centrifuges are not the best but I find the practical works anyway.
I cannot seem to find the Note on how to make the Isolation Medium, can anybody direct me please. I do not know what the isolation medium is made up of.
I thought the first pellet would be the nucleus and that you had to centrifuge again at a lower speed to get the chloroplast.. can you explain this to me please?
"Chloroplasts can be isolated by grinding green leaves in a cold medium of suitable osmotic and ionic strength, such as the isolation medium used here." www.techknow.org.uk/wiki/index.php?title=Hill_Reaction I think it's a bit like the cold, buffered, and isotonic solution used for homogenation
Zarina Oge at A level there is t an appropriate stat test for this. Just a bar chart with range bars or standard deviations to see if they overlap would be fine. Overlapping SDs it ranges will mean that the differences between the mean times are not significant.
The result shows that red light gives higher rate of photosynthesis than blue light. I thought blue light has shorter wavelength and higher energy and should give higher rate? Please help...
Hi. It is not about the energy of the light. It is the fact that the main photosynthetic pigments Chlorophyll A and B absorb red and blue light (but reflect other colours) so these are the colours which mainly power photosynthesis. In the experiment I did there were other variables for example the thickness and transparency of the different filters may have varied. This could also influence the results making them less valid. The video is simply a guide to the method used when investigating the rate of the light dependant reactions of photosynthesis.
thanks for saving my life cause our teacher had no idea how to do this and taught us it completely wrong :)
w teacher 🔥
Thank you so much!! This video helped me a lot. My TAs are so confused and confusing. They always do mistakes, some of which are intolerable!!! Last experiment was about cellular fractionation, and they used 8000 g by mistake instead of the written 800g in the manual as the first centrifugation. About 95% of our experiments have failed. They even failed to do Gram staining properly. Let alone their broken English and intolerance to students' questions. They almost rarely understand the questions asked anyway, and even if they understand the question they most probably give very misleading and very wrong answers. I'm so jealous to know that some students have such good professors and TAs. Good lock guys and please appreciate what you have!
Very kind words. Where are you at school?
So cool! It's like a science cooking show. Regards from UF
Great video! Have to do something similar and write it up as part of a biology SKE but don't have chance to see the experiment live. This is a massive help and really well explained. Bit of an abrupt ending though...
4:09 Why does centrifuging at high speeds cause chloroplasts to sediment as pellets? I thought they were part of the supernatant since they're lighter in mass and thus less dense
Shak Pherze it depends how fast you spin them. Usually you would spin slowly to remove debris if cell walls leaving the chloroplasts in the supernatant then spin the supernatant again to obtain a pellet containing chloroplast which you can then resuspend in buffer to obtain fairly pure chloroplasts. To be honest those little school centrifuges are not the best but I find the practical works anyway.
Drinking game; take a shot every time she says 'okay'
I cannot seem to find the Note on how to make the Isolation Medium, can anybody direct me please. I do not know what the isolation medium is made up of.
What should the concentration of the DCIPIP be?
Thanks for this. We did the practical but either had no colour change or just didn’t time it and our write up is due tomorrow.
Thank you so much this video was a live saver.
For the isolation medium, can the sucrose and KCl be added in liquid form?
Yes it should be a solution. There should be a note on the video to tell you the concentrations.
The best video on this thank you!!
I thought the first pellet would be the nucleus and that you had to centrifuge again at a lower speed to get the chloroplast.. can you explain this to me please?
Hanan Ajay the nuclei will also be in that first pellet. It will not be pure chloroplast.
what is the isolation medium needed for?
why?
"Chloroplasts can be isolated by grinding green leaves in a cold medium of suitable osmotic and ionic strength, such as the isolation medium used here." www.techknow.org.uk/wiki/index.php?title=Hill_Reaction
I think it's a bit like the cold, buffered, and isotonic solution used for homogenation
C
Is it okay to use another buffer which is not phosphate as long as it has ph7? Our school somehow does not have phosphate buffer
what statistical test would you use to analyse the results?
Zarina Oge at A level there is t an appropriate stat test for this. Just a bar chart with range bars or standard deviations to see if they overlap would be fine. Overlapping SDs it ranges will mean that the differences between the mean times are not significant.
The result shows that red light gives higher rate of photosynthesis than blue light. I thought blue light has shorter wavelength and higher energy and should give higher rate? Please help...
Hi. It is not about the energy of the light. It is the fact that the main photosynthetic pigments Chlorophyll A and B absorb red and blue light (but reflect other colours) so these are the colours which mainly power photosynthesis. In the experiment I did there were other variables for example the thickness and transparency of the different filters may have varied. This could also influence the results making them less valid. The video is simply a guide to the method used when investigating the rate of the light dependant reactions of photosynthesis.
Thanks for your response! Please make more videos like this, it is really helpful!
where is note on preparation of loading buffer ?
I had to do this experiment in Biology 101....given the complexity of the experiment that doesn’t seem right...
where is preparation procedure for phosphate buffer
Hi, can I ask what speed is the centrifuge set at?
ZnZn84 my centrifuge is not the best so I just set it to the highest speed it will go.
Hi, which will be what rpm?
ZnZn84 -16000 rpm but 10000 will work.
Biology Practicals and Revision Biology Tutor
OK thanks a lot.
Really helpful
Is this for a new spec ?
All the practical activities are required by AQA A level Biology new spec from 2016 onwards.
where is the note on preparation of isolation medium?
thank you!
Give it. A try. Should be ok. Make sure your spinach is really fresh too.
Thanks
where is the note on preparation of isolation medium?
Thanks
where is the note on preparation of isolation medium?