Nothing like speeding through these videos on 2x speed 2 hours before your Paper 3 exam - thanks for the quality content! Here's to hoping the paper won't be as bad as Paper 2
wow your amazing that one video taught me more than what i learnt in 3 weeks with my teacher! so if possible please continue to make videos especially on ecosystem thank you for making such good videos especially before our exam which is in 2 days :)
Thank you! I'm glad you found it useful :) I will keep making videos. In terms of ecosystem, I'm planning to do one on nitrogen cycle perhaps next week. Good luck with your exam!!!
I know this is too late but i wish you would reduce the cuts in the video, it gets kind of confusing when suddenly there's a cut in voice and your hand teleports and there's new information on the screen. Otherwise thank you very much, very helpful video
Thank you very much for these videos. They are always clear and well explained. I use your videos to plan my OCR a level biology lessons. My students also use your videos to revise. I wish you all the best. Well done
Sorry it's a bit long but hope this helps! A DNA chip is a flat surface that are made up of regularly organised DNA probes. So imagine if you're drawing a 5x5 table: each box/cell is a specific group of DNA probes (short strand of DNA that are designed to attach to certain genes), and the whole table itself is the DNA chip - so in this case, our DNA chip has 25 different groups of DNA probes in total. Each group of DNA probes is designed to only bind to a certain gene that has been expressed (so they bind to the specific RNA produced by specific genes). A different coloured fluorescent dye is attached to each RNA that have been extracted - eg. Red dye attached to RNA A, blue dye attached to RNA B, green dye attached to RNA C... When you wash the mixture of RNAs over the DNA chip, the RNA will bind to its specific group of DNA probes - Eg. Red RNA A binds to DNA probes in cell 1; Blue RNA B binds to DNA probes in cell 5; Green RNA C binds to DNA probes in cell 10. If you then pass the DNA chip under UV light/laser detection, you can then see the intensity of fluorescent light/signal shown on the DNA chip at different specific DNA probes "cells". Then from that you'll be able to tell which genes are expressed the most based on the intensity of light detected (by corresponding the colour of light to the gene). Right then, how does all this link to gene therapy? Gene therapy is replacing a faulty gene with a healthy gene, in either somatic cell or germline. I think one way to apply DNA chips into gene therapy is that we can use DNA chips to identify which gene is faulty (either it's not expressed enough, like not enough insulin made; or expressing too much, like growth receptors in cancer), in order to make a diagnosis of the actual genetic condition. Once we use a DNA chip to find out which gene is faulty, we can then make a decision on which condition it is, then know which gene to replace. We can also use this knowledge to design an appropriate vector to bring the healthy gene to the faulty gene. Since it needs to bind to and recognise the faulty gene, then it would be complementary to it - so you can design RNA probes (identical to the ones made by the patient to do the DNA chip test) which carries the necessary chemicals/genes to the exact location of the faulty gene to do the necessary steps... At this point I would have no idea exactly how it works, but this is my best estimate.
I'm really glad that they're helpful :D And it's great that you're asking questions... I enjoyed thinking my way and formulating my answer for that one XD Good luck with revision and thanks for watching!
Are the differences each persons DNA profile down to restriction endonucleases cutting at different restriction sites or the different satellite regions?
Sorry if this is too late (since paper 3 today!)... The differences are due to the different number of DNA repeats between each restriction site in each person. So a person can have 10 repeats of his satellite DNA section, but another can have 50 repeats, so therefore the resulted fragments would be of different lengths. Hope this helped and all went well today. Thanks for watching :D
Good question. As far as I'm aware, they do extract the whole genome. It'll be difficult to only extract the bit that we want when all the other impurities are mixed within. It's only when in PCR that we amply just the part of the DNA that we want. Hope this helps!
I was interested in this out of curiosity. So when someone says this person’s DNA is 1 out of a trillion are they referring to these fragments and are these fragments’ combinations so many that the “1 in a trillion” is possible to determine?
It's on both strands. It's the specific section of DNA that is repeated, which includes both strands, just complementary to each other but the repetition is still obvious.
Another question: Is there any reason why you separate the double standard DNA into single stranded DNA. Is it to separate the 5 and 3 end and 3 to 5 end strands and compare those strands to other people strands.l
Don't think blood is the ideal source of DNA since it doesn't contain any DNA and a nucleus. Question: Can you use electrophoresis to determine whether a gene is polymorphic and monomorphic, and if yes, how would it be displayed. P.S: Great video
Keep in mind that blood contains red blood cells, white blood cells, platelets and plasma! So even if there aren't any DNA in RBC and plasma, you can still get them from WBC and platelets :) In response to your question, yes, gel electrophoresis is used for this purpose, but it's hard to explain how it works in a comment... I'd recommend referring to p.276-277 in the OCR AS textbook, you can see how it looks like :) Hope this helped in some ways... Thanks for watching!
I’m so glad you’re still reading all these comments years later. Thank you for helping a generation of biologists !
Haha thanks! I can't keep up replying to all comments, but I do read every single comment I get 🩵
watching this a day before paper 2 !! thank you for your videos, best biology videos i've watched to help me understand the content
Glad to know you find them helpful! Rest well tonight, all the best for tomorrow and thanks for watching! :D
Saaaame good luck for tomorrow
@@BioRach thank you!!
@@isabelleliang9704 thanks you too :D
Same, I'm actually watching this video before the A-level Biology Paper 2 exam now. I agree with you.
Nothing like speeding through these videos on 2x speed 2 hours before your Paper 3 exam - thanks for the quality content! Here's to hoping the paper won't be as bad as Paper 2
Haha great to hear that the videos are helpful!! Thanks for watching and good luck with paper 3 today!!! :D
Absolute stellar explanation you have a talent for teaching
wow your amazing
that one video taught me more than what i learnt in 3 weeks with my teacher! so if possible please continue to make videos especially on ecosystem
thank you for making such good videos especially before our exam which is in 2 days :)
Thank you! I'm glad you found it useful :)
I will keep making videos. In terms of ecosystem, I'm planning to do one on nitrogen cycle perhaps next week.
Good luck with your exam!!!
@@BioRach Thank you , can you make videos more on manipulating genomes
This was really useful - I finally get the separation step of DNA profiling!! Thank you!!!
Glad it's helpful! :D Thanks for watching!
Hi, 6:00 on a markscheme it says that you should cut the DNA into varying lengths before you amplify it.
I know this is too late but i wish you would reduce the cuts in the video, it gets kind of confusing when suddenly there's a cut in voice and your hand teleports and there's new information on the screen. Otherwise thank you very much, very helpful video
Thank you so much for this video. Keep up the good work! you're saving students from all around the world!
haha I hope the videos are of help! I'll keep going (making another one soon)... Good luck to you with your revision and thanks for watching :D
Wow thank you!! This whole chapter was so confusing for me before
Thank you very much for these videos. They are always clear and well explained. I use your videos to plan my OCR a level biology lessons. My students also use your videos to revise. I wish you all the best. Well done
Thank you so much! Glad to know it helps with lesson planning :D
Hi i was just wondering where DNA chips, DNA probes, gene therapy and vectors for gene therapy tie in, thank you so much!
Sorry it's a bit long but hope this helps!
A DNA chip is a flat surface that are made up of regularly organised DNA probes. So imagine if you're drawing a 5x5 table: each box/cell is a specific group of DNA probes (short strand of DNA that are designed to attach to certain genes), and the whole table itself is the DNA chip - so in this case, our DNA chip has 25 different groups of DNA probes in total. Each group of DNA probes is designed to only bind to a certain gene that has been expressed (so they bind to the specific RNA produced by specific genes). A different coloured fluorescent dye is attached to each RNA that have been extracted - eg. Red dye attached to RNA A, blue dye attached to RNA B, green dye attached to RNA C...
When you wash the mixture of RNAs over the DNA chip, the RNA will bind to its specific group of DNA probes - Eg. Red RNA A binds to DNA probes in cell 1; Blue RNA B binds to DNA probes in cell 5; Green RNA C binds to DNA probes in cell 10.
If you then pass the DNA chip under UV light/laser detection, you can then see the intensity of fluorescent light/signal shown on the DNA chip at different specific DNA probes "cells". Then from that you'll be able to tell which genes are expressed the most based on the intensity of light detected (by corresponding the colour of light to the gene).
Right then, how does all this link to gene therapy?
Gene therapy is replacing a faulty gene with a healthy gene, in either somatic cell or germline. I think one way to apply DNA chips into gene therapy is that we can use DNA chips to identify which gene is faulty (either it's not expressed enough, like not enough insulin made; or expressing too much, like growth receptors in cancer), in order to make a diagnosis of the actual genetic condition. Once we use a DNA chip to find out which gene is faulty, we can then make a decision on which condition it is, then know which gene to replace. We can also use this knowledge to design an appropriate vector to bring the healthy gene to the faulty gene. Since it needs to bind to and recognise the faulty gene, then it would be complementary to it - so you can design RNA probes (identical to the ones made by the patient to do the DNA chip test) which carries the necessary chemicals/genes to the exact location of the faulty gene to do the necessary steps... At this point I would have no idea exactly how it works, but this is my best estimate.
BioRach thank you so much that was so useful!! Love all your videos they have really helped me!
I'm really glad that they're helpful :D And it's great that you're asking questions... I enjoyed thinking my way and formulating my answer for that one XD Good luck with revision and thanks for watching!
Can you make videos on immunology and diseases please 💘💘 you’re amazing I’m so happy I found you before it was too late
I have! Check out Ch.12 playlist :) glad you found the videos helpful, and thanks for watching!
Thank you so much! Great explanation !!
Glad you find it helpful! Thanks for watching :D
I watched many but got now when saw this video really really helpful
Are the differences each persons DNA profile down to restriction endonucleases cutting at different restriction sites or the different satellite regions?
Sorry if this is too late (since paper 3 today!)...
The differences are due to the different number of DNA repeats between each restriction site in each person. So a person can have 10 repeats of his satellite DNA section, but another can have 50 repeats, so therefore the resulted fragments would be of different lengths.
Hope this helped and all went well today. Thanks for watching :D
thank you for explanation
i wanna to know about microsatellite
Great video, good detail
your really awesome.
one small question though, in step 1 when you extract DNA from the blood is the whole genome we are extracting?
Good question. As far as I'm aware, they do extract the whole genome. It'll be difficult to only extract the bit that we want when all the other impurities are mixed within. It's only when in PCR that we amply just the part of the DNA that we want. Hope this helps!
love your vids sooo much. I am so appreciative for you spending your time to make these beautiful learning resources
At 8:00 do you say 'Nylon sheet' if so then I can't find this in the textbook
P.s. very good video
Yes I did, though exams won't ask you specifically this information.
really helpful thank you so much!
I was interested in this out of curiosity. So when someone says this person’s DNA is 1 out of a trillion are they referring to these fragments and are these fragments’ combinations so many that the “1 in a trillion” is possible to determine?
This is so helpful thank you so much
Thank you!!!!!!!!!! You are lifesaverr
How to get whole videos
the video is veryy helpful to understand the whole topic thank youu!!
Glad it helps! :D
brilliant, thankyou !
Is the satellite DNA on the 5 to 3 end as that's where we read DNA
It's on both strands. It's the specific section of DNA that is repeated, which includes both strands, just complementary to each other but the repetition is still obvious.
@@BioRachThanks for clarifying that.
Another question: Is there any reason why you separate the double standard DNA into single stranded DNA. Is it to separate the 5 and 3 end and 3 to 5 end strands and compare those strands to other people strands.l
Not quite. It's to allow the binding of DNA probes which carry a fluorescent dye. This allows the strands to be seen on the gel.
Thanks again for clarifying that
Thank you so much for the viedo！So helpful!！！
👍👍👍 Great Video!!!!
Don't think blood is the ideal source of DNA since it doesn't contain any DNA and a nucleus.
Question:
Can you use electrophoresis to determine whether a gene is polymorphic and monomorphic, and if yes, how would it be displayed.
P.S: Great video
Keep in mind that blood contains red blood cells, white blood cells, platelets and plasma! So even if there aren't any DNA in RBC and plasma, you can still get them from WBC and platelets :)
In response to your question, yes, gel electrophoresis is used for this purpose, but it's hard to explain how it works in a comment... I'd recommend referring to p.276-277 in the OCR AS textbook, you can see how it looks like :)
Hope this helped in some ways... Thanks for watching!
@@BioRach Thank you very much!!!!! Your videos really helped me for paper 3
Thank you!
does that mean promoter/operator sites are introns ????
Yes :) They don't produce any proteins, so are introns. But being introns, they control the expression of exons, so they are still important!
does satellite dna code for genotypes or phenotypes?
Sorry I'm not sure what you're asking about - Perhaps double check what you know as genotype and phenotype?
genotype
So helpful, cheers x
You havent done 21.5
Good video but you talk too fast. I was struggling to catch up, had to pause and rewind and replay.
haha sorry, something I've been working on. Thanks for the reminder and thanks for watching!