this is such an incredible video, thank you!! you make it so easy. the more I watch, the more I realise how much my biology teacher overcomplicated it, and how unnecessary huge chunks of text are.
Lily - you've just made my day! 😁 That it simply the best compliment you could give me!! A level biology is a horrible amount to learn but can be pretty straightforward. Check out my website for ridiculously good value sets of A level videos.. and a 'How to improve your grade to A*' freebie! www.biologycarol.co.uk My new channel trailer explains all... th-cam.com/video/7sfl8_aAWk0/w-d-xo.html
Carol, I wish I had you as my biology teacher at school. I would probably gone on to study medicine. You are extremely precise with your explanations and answers. Respect !!!!! I love your explanations.
Thankyou so much for taking the time out to make these videos, they make revision so much easier! I really appreciate the time and effort that you put in to help so many a level students :)
Thank you for the thank you! Do feel free to check out my website where ALL my videos are (covering whole of AQA and OCR A syllabuses by end Jan) - www.biologycarol.co.uk. This is me seriously trying to make A level biology accessible to all students regardless of family income...
I just want to thank you for making these videos, I’m a retake student and I feel like you’ve helped me so much in this short period of time. I’ll definitely be recommending you to my friends and family in the year below taking biology a level.
Thank you SO much! All my videos (each with me going through exam questions at the end) are on my website www.biologycarol.co.uk if you're interested. This is me genuinely trying to make A level biology accessible to all students, regardless of family income. Livestreams and video 'favourites' are on TH-cam 😊
@@biologycarol Thank you for replying for my comment! I would surely love to look onto your website to learn further. Thank you for sending me the link too! I appreciate your efforts to help students learn easily, world wide ☺️. Thank you once again 👍
Hey, first of all thank you for such a great video. Initially, it was a lot of info to get my head around, but after a couple of replays I managed to figure it out. Keep up the great work and thanks for the time stamps as well.
Delighted it helped😁 Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income.
This is the first one of your videos I have watched as we are in quarantine atm and I intend to continue and watch all the videos on your channel as I have found this one very useful and I like your method of teaching! Thank you :)
I'm delighted! Have you spotted that I Livestream every Tues and Thurs at 5pm? Thurs = Practical techniques and understandingthe practical terminology e.g. validity, accuracy etc. Tues = topic voted for on my Community tab. Enjoy😂!
You’re very lovely 😊. Do tell your friends too😁. And have you checked out the website www.biologycarol.co.uk?! All my (edited!) videos covering both years of A level for £50 for the year. And you can earn your subscription back! And there’s a freebie😂!
SO pleased! Just so you know...all my videos (each with me going through exam questions at the end) are on my website www.biologycarol.co.uk if you're interested. This is me genuinely trying to make A level biology accessible to all students, regardless of family income. Livestreams and video 'favourites' are on TH-cam 😊
Carol, do we need to know about Phagocytes forming a phagosome to engulf the pathogen and the phagosome fusing with a lysosome to form a phagolysosome to secrete hydrolytic enzymes to destroy the pathogen?
Wow I just found this!! I’ve had a surprise test dumped on me for Monday so I’ve been cramming the immune system and it just seemed so confusing. This had made it so much clearer thank you so much!
Woo! Hoo! Hope it went well x Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income. TH-cam pays very little (A level biology is a little niche😁) and this is a way that I can continue to make content that's useful to students. The website includes a way of earning money off me and there's a freebie too 'How to improve your grade up to an A*’ - so grab that at least!
Hi Edward, How fantastic is that!! That has just made me smile so much - cheers! SO pleased it helped. Immunity is a bloomin' nightmare for most students - and AQA don't make it any easier I think...
Brilliant! I'm delighted 😁 Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income. TH-cam pays very little (A level biology is a little niche!) and this is a way that I can continue to make content that's useful to students. The website includes a way of earning money off me and there's a freebie too 'How to improve your grade up to an A*’ - so grab that at least!
Thanks for this 🙂 - its why i include exam questions at the end of every video. I'm aware I could do with doing more whole exam papers - its all a matter of time, or lack of it...
Thank you! I've put your request on my list, and i will do one asap. IF these videos are helpful to you, please recommend me to friends - I am serious about making A level biology accessible and (relatively) simple and would like to get that message to as many students as possible. Thanks Emer!
Woo! Hoo! FYI all my videos are on my website www.biologycarol.co.uk - this is my attempt at making A level biology accessible regardless of any students family financial situation.
Thank you so much for this video! It is so useful! I’m in year 12 and I have an end of year assessment soon (online) so this has really refreshed my memory on the topic😊
😁 I assume you mean on my website...www.biologycarol.co.uk? I will have covered the whole of AQA and OCR A syllabuses by end Jan. This is me seriously trying to make A level biology accessible to all students regardless of family income...
Thank you very much for this video, I was really struggling to understand the process as a whole but this diagram makes all the individual bits of content come together perfectly. So glad I found this channel! Copied out the diagram and hung it on my bedroom wall haha. P.S. Is there any chance that you could do a video on AQQ AS absorption of the products of digestion? I don’t really understand lipid absorption or glucose absorption. Thank you!
Hi Sophie, thanks for the encouragement 😊 - even teachers need that ! I have digestion already down on my list of requests and I'm keeping a rough tally of numbers and its working its way to the top. Will try and do before Paper 1. Are you Yr 13?!
biology carol No problem, it’s just the truth. I have recommended your channel to my classmates too as I know they’ll benefit from it. :) Nope, I am in year twelve. My AS mocks are week beginning June 4th so hopefully you’ll find some time before them for a digestion video (but if not, it’s no problem, I will just wrestle with textbook jargon.)
Thank you, I really struggled to understand this during my lesson but I think I’ve gotten it now! I’m currently in year 12 and I have my bio exam in two days, wish me luck! :)
The video was great, thanks. Just to clarify something here: to my belief, the cytotoxic T cells are produced by the T cells which have the receptor complimentary to the antigen of the original pathogen (correct me if I’m wrong). Thus, the cytotoxic T cells must contain the receptors which are complimentary to the pathogen’s antigen. If this is correct, how is it possible for the cytotoxic T cells to kill host cells? As the antigen on the host cell would be (to my understanding) different to that of the virus (the pathogen). Any response would be appreciated, thanks.
MY RESPONSE IN CAPITALS AND 😊! The video was great, thanks 😊. Just to clarify something here: to my belief, the cytotoxic T cells are produced by the T cells which have the receptor complimentary COMPLEMENTARY ! COMPLIMENTARY MEANS SOMETHING DIFFERENT (DONT WORRY YOU WONT LOSE MARKS THROUGH) to the antigen of the original pathogen (correct me if I’m wrong THAT'S RIGHT). Thus, the cytotoxic T cells must contain NOT 'CONTAIN' - HAVE ON THEIR CELL SURFACE MEMBRANE the receptors which are complimentary to the pathogen’s antigen YEP. If this is correct, how is it possible for the cytotoxic T cells to kill host cells? BECAUSE HOST (BY THIS I MEAN THE BODY WHICH HAS BEEN INFECTED) CELLS WHICH ARE INFECTED WITH PATHOGENS (ESPECIALLY VIRUSES BUT COULD BE BACTERIA) PRESENT THE PATHOGEN'S ANTIGEN ON ITS CELL SURFACE MEMBRANE (JUST AS PHAGOCYTES DO) AND LIKE PHAGOCYTES, BECOME ANTIGEN PRESENTING CELLS. As the antigen on the host cell would be (to my understanding) different to that of the virus (the pathogen) NO - THE BODY'S CELLS DISPLAY THE ANTIGEN ON THEIR CSM. THIS BASICALLY ACTS AS A FLAG/SIGNAL TO THE CYTOTOXIC T CELLS TO COME AND DESTROY THE CELL (THEY 'TAKE ONE FOR THE TEAM'). WHY DO YOU THINK THE PATHOGEN'S ANTIGEN IS NOT THE SAME AS THAT PRESENTED ON THE PHAGOCYTE OR INFECTED CELL?? SORRY - USING CAPITALS FEELS LIKE IM SHOUTING AT YOU - I'm not !😂
biology carol thanks, that clarifies a lot. I guess, as the infected host cell would be caused by a virus (or bacteria, but when writing this I thought host cells were only infected/invaded by viruses), I didn’t think it would go through the process in which a phagocyte does to form an antigen presenting cell; I thought the virus would just infect the cell and continue to reproduce, with no formation of an antigen presenting cell on a host cell. However, as I now know the host body cell presents the pathogen’s antigens, it makes sense to me how the cytotoxic T cells are able to bind to the antigens of the antigen presenting cell (the host cell) and kill the cell and virus (or bacteria).
@@ShadowMan-wq7ib I think you've got it! you're right - infected host cells CAN be infected by some bacteria and definitely viruses and these cells become APCs. hopefully not to blow your brains too much, early cancer cells can also be APCs (our body's immune system deals with them before we even know - phew!) as well as (may be more obviously) cells of transplant organs - hence rejection.
Love the video. Few questions. 1) Does the T-helper cell turn into a cytotoxic killer cell? Or is the killer cell already there ? Or do they divide into killer cell? 2) can B-cells release antibodies on viruses in the blood stream? 3)why does each type of cell divide into more of them selves? Other than those three, thank you for the video ! Really appreciate the explanation ☺️
The initially activated T helper cell divides by mitosis (clonal expansion) and differentiates into, among others, cytotoxic T cells (T killer cells or T K cells ). They are not already there, they’re made from the initial T H cell. Hope that helps x
Phagosomes - yes. not the term phagolysosome but you do need to know that lysosomes migrate towards and fuse with the phagosome, so that the digestive enzymes digest the pathogen. The fusion of the lysosome and a phagosome IS the phagolysosome but I don't believe you need that term.
I haven't seen the 2023 papers but heard about them! The grade boundaries don't change that much from year to year (for AQA and OCR at least) and you can easily Google them. Not sure that's going to help you that much😬
Thanks for this but no, I DID mean 'or polysaccharide'. Most antigens are proteins (polypeptides), but they can be glycoproteins or, indeed polysaccharides. The exam answer is nearly always 'Foreign protein that causes the production of antibodies'
Hi Carol, thank you so much for these videos they are saving me right now while preparing for mocks! Was wondering about the invlovement of Memory T cells, Killer T cells and Supressor T cells? Thank you!
You don't need to know details about those for AQA but... Memory T cells stay in the blood and stimulate TH cells if the infection hits again T Killer cells kill infected cells by punching a hole in their cell membrane T Supressor cells stop the immune system attacking self cells in the war that is a pathogen infection. My OCR immunity video covers these in more detail, but its on my website where my full complement of videos are. Do take a look www.biologycarol.co.uk 😊
Hi there, thanks for this great video. Around the 13:00 mark, you talk about how the B cell needs to bind to antigen but also the Th cells. I know that B cells have antibodies complementary to the antigens, but do the B cells have receptors which bind specifically to the Th cells. Or is it like the process on the AQA a level 2nd edition textbook (curly haired boy holding a test tube) where the Antibodies of the B cells bind to the antigen, it then enters the cell by endocytosis and it is then presented on its surface. Then the Th cells bind to these presented antigens causing the B cell to be activated. Thank you
I’m really sorry- I’ve just realised that I missed this comment. Your description is more detailed than mine and you are correct. I have simplified the description but I actually prefer the accuracy of yours. Just so you know, I’ve never seen either of our levels of detail required for a mark in the exam. Hope that helps at least.
This was an incredibly informative video. I do have one question about the activation of b cells. Are they required to bind to an antigen and also a specific helper t cell. The second 6 marker didnt specify that it had to bind to t cells.
Thank you x And 'Yes' they are! Its jsut that that is not always a mark point in an exam Q - doesn't mean to say it isn't true though! Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income. TH-cam pays very little (A level biology is a little niche!) and this is a way that I can continue to make content that's useful to students. The website includes a way of earning money off me and there's a freebie too 'How to improve your grade up to an A*’ - so grab that at least!
Thank you so so much for this video!! You do not understand how helpful this is!! Would it be right to say then, phagocytosis happens first, presents the antigens on their surface, which t helper cells can bind to, of which B cells are activated by, stimulating the production of antibodies?
Absolutely - a level immunity in a nut shell!! Just remember that it is the memory cells that cause the immunity and the antibodies cause the pathogen to be destroyed (ie for you to recover from the disease). Well done!
Hi - my teacher has taught this slightly differently: at 11:32 you say that binding of an antigen (presented on an APC) to a helper T-cell receptor then activates the T helper cell to differentiate into a cytotoxic T cell. My understanding is that T helper cells (CD4+) and cytotoxic T cells (CD8+) differentiate in the thymus, before they are released into the lymphatic system and thus exist as two distinct populations already. Activation of the t helper cell leads to it dividing by mitosis and helping to activate cytotoxic t cells. If I've got the wrong end of the stick please do say. Thank you!
Detail required at A level. It’s great that you’ve been taught to a greater level of detail but if you’re taking a British A level that extra detail won’t get you more marks. Hope that puts your teaching in context x
@@biologycarol Brilliant, thank you for explaining! I was just slightly concerned I'd misunderstood something, phew! Thanks a lot, you're videos are really helpful! One other quick question about recombinant DNA if that's ok - after you've cut human DNA with restriction enzymes, how is the gene of interest then isolated? Is that when you use gel electrophoresis? But then if you don't know the sequence of the gene how do you isolate it? Or do you use gel electrophoresis after you've done the cloning? Thank you!!!
Hi Kalum! PCR would be used to duplicate the DNA sample, restriction enzymes would then be used to cut out the gene of interest. Assuming that you know the length of the gene of interest (which we do now as we can sequence genomes relatively easily), the gene can be separated from the rest of the DNA by gel electrophoresis because the latter technique separates by length of DNA and charge. Does that clarify how the techniques would e used together or is there something else that’s confusing you ? X
@@biologycarol Many thanks for your reply, much appreciated! Yes that clears it up, thank you. Out of interest, how would you seperate the band of interest if there is more than one DNA fragment of the same size? If REs cut at a specific site in the genome, presumably not every fragment generated will be of a different size? Hope that makes sense! Thanks!
😁 Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income. TH-cam pays very little (A level biology is a little niche!) and this is a way that I can continue to make content that's useful to students. The website includes a way of earning money off me and there's a freebie too 'How to improve your grade up to an A*’ - so grab that at least!
The two exam boards AQA AND OCR have (rather unusually) very different emphases on what is required to be known for this topic. All the content is true (!) but I ended making 2 vids because of this. One vid constantly explaining what was different between the exam boards would have been too confusing.
I've put it (or should i say them - think it might be more than 1...) on the list. They will happen, i just cant promise when. the request list's getting quite long!
No - but I see why you've asked! The 'protein (or polysaccharide)' isn't me saying that another name for a protein is a polysaccharide; I'm saying that an antigen is nearly always a protein, but can sometimes be a polysaccharide. Does that make sense now? Hoping so xx
![[Sub Thai] APT. - ROSÉ & Bruno Mars](http://i.ytimg.com/vi/bYjhzP8x_uc/mqdefault.jpg)
Thank you so much Carol! As a year 12 student understanding this has been a nightmare - but this has made it so much clearer!
This is the best thing that has ever happened to me
😂
Pleased it seems to have helped! Immunity IS a bit if a nightmare, I'll give you that.
🥲me too
this is such an incredible video, thank you!! you make it so easy. the more I watch, the more I realise how much my biology teacher overcomplicated it, and how unnecessary huge chunks of text are.
Lily - you've just made my day! 😁 That it simply the best compliment you could give me!!
A level biology is a horrible amount to learn but can be pretty straightforward.
Check out my website for ridiculously good value sets of A level videos.. and a 'How to improve your grade to A*' freebie! www.biologycarol.co.uk
My new channel trailer explains all... th-cam.com/video/7sfl8_aAWk0/w-d-xo.html
Carol, I wish I had you as my biology teacher at school. I would probably gone on to study medicine. You are extremely precise with your explanations and answers. Respect !!!!! I love your explanations.
SO pleased they are helpful 😊
This is AMAZING!!! thank you so much
Thankyou so much for taking the time out to make these videos, they make revision so much easier! I really appreciate the time and effort that you put in to help so many a level students :)
Thank you for the thank you!
Do feel free to check out my website where ALL my videos are (covering whole of AQA and OCR A syllabuses by end Jan) - www.biologycarol.co.uk. This is me seriously trying to make A level biology accessible to all students regardless of family income...
I just want to thank you for making these videos, I’m a retake student and I feel like you’ve helped me so much in this short period of time. I’ll definitely be recommending you to my friends and family in the year below taking biology a level.
Thank you so much for the thank you😊
I’m absolutely delighted to have been able to help you - every teacher’s wish!
I had such a hard time with this topic, you have made this so easy to understand. Thank you so much!!
I am SO glad, and thank you for the encouragement x
fyi www.biologycarol.co.uk !
Thank you so much Carol😀 I loved the way you taught the concept... Looking forward for teaching us like this for other lessons too!
Thank you SO much! All my videos (each with me going through exam questions at the end) are on my website www.biologycarol.co.uk if you're interested. This is me genuinely trying to make A level biology accessible to all students, regardless of family income.
Livestreams and video 'favourites' are on TH-cam 😊
@@biologycarol Thank you for replying for my comment! I would surely love to look onto your website to learn further. Thank you for sending me the link too! I appreciate your efforts to help students learn easily, world wide ☺️. Thank you once again 👍
Hey, first of all thank you for such a great video.
Initially, it was a lot of info to get my head around, but after a couple of replays I managed to figure it out. Keep up the great work and thanks for the time stamps as well.
Delighted it helped😁
Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income.
You are such a lifesaver thank you so much!! Did not understand immunity at all until watching this video!!!
Fantastic! Really pleased it makes sense now -makes the learning of it easier too 😊
This is the first one of your videos I have watched as we are in quarantine atm and I intend to continue and watch all the videos on your channel as I have found this one very useful and I like your method of teaching! Thank you :)
I'm delighted! Have you spotted that I Livestream every Tues and Thurs at 5pm? Thurs = Practical techniques and understandingthe practical terminology e.g. validity, accuracy etc. Tues = topic voted for on my Community tab. Enjoy😂!
Just subbed this has been more helpful than a lesson at school thank you
You’re very lovely 😊. Do tell your friends too😁. And have you checked out the website www.biologycarol.co.uk?! All my (edited!) videos covering both years of A level for £50 for the year. And you can earn your subscription back! And there’s a freebie😂!
this video is a life saver!!! thank you for making for making this video, it really helped me with my exams :)
SO pleased!
Just so you know...all my videos (each with me going through exam questions at the end) are on my website www.biologycarol.co.uk if you're interested. This is me genuinely trying to make A level biology accessible to all students, regardless of family income.
Livestreams and video 'favourites' are on TH-cam 😊
@@biologycarol I'll look into it! Thanks for replying 😁
Carol, do we need to know about Phagocytes forming a phagosome to engulf the pathogen and the phagosome fusing with a lysosome to form a phagolysosome to secrete hydrolytic enzymes to destroy the pathogen?
yes
Yes - the only term there that is not essential for AQA is phagolysosome (and I can't remember seeing it in OCR A mark schemes...)
This is the best video ever!!
😂
Glad you like it!
Just so you know for next year www.biologycarol.co.uk exists 😊
Wow I just found this!! I’ve had a surprise test dumped on me for Monday so I’ve been cramming the immune system and it just seemed so confusing. This had made it so much clearer thank you so much!
Woo! Hoo! Hope it went well x
Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income. TH-cam pays very little (A level biology is a little niche😁) and this is a way that I can continue to make content that's useful to students. The website includes a way of earning money off me and there's a freebie too 'How to improve your grade up to an A*’ - so grab that at least!
Played your video for the entire class today. Everyone loved it. ❤️❤️❤️
Hi Edward, How fantastic is that!! That has just made me smile so much - cheers! SO pleased it helped. Immunity is a bloomin' nightmare for most students - and AQA don't make it any easier I think...
Thank you so much this is so helpful, online learning has been a nightmare and this really cleared it up!
Well that's just made my day😁
Just in case you're interested, I have a website www.biologycarol.co.uk where all my videos are...
Thank you! The video has been really helpful for preparing for my topic test!
Brilliant! I'm delighted 😁
Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income. TH-cam pays very little (A level biology is a little niche!) and this is a way that I can continue to make content that's useful to students. The website includes a way of earning money off me and there's a freebie too 'How to improve your grade up to an A*’ - so grab that at least!
This was amazing thank you Carol! Could you possibly make a video about monoclonal antibodies please?😊
Thank you so much, Sarah, that's really encouraging for a TH-cam novice! I'll add MAbs to my list and do my best! Are you Yr 12 or Yr13?
13
@@ibrahimshafi2064 she never asked you Ibrahim
@@lh8474 ok Karen
It vez really very helpful 👏🏻 Thnx fer yer kind efforts 😊
So pleased 😊
Btw www.biologycarol.co.uk exists 🙂
Thank you Carol, this is really useful ,especially the techniques of answering questions.
Thanks for this 🙂 - its why i include exam questions at the end of every video. I'm aware I could do with doing more whole exam papers - its all a matter of time, or lack of it...
Hey, i was wondering about the ELISA Test and monoclonal antibodies? :) and this video is extremely helpful, Thanks!
Fantastic - pleased it helped. ELISA and MAbs are on my list!
Excellent video.
SO pleased it's been useful.
It's a real nightmare topic, isn't it!
Thank you so much for this amazing video Carol! If you could do a video on the ELISA test and monoclonal antibodies it would be much appreciated! :)
Thank you! I've put your request on my list, and i will do one asap.
IF these videos are helpful to you, please recommend me to friends - I am serious about making A level biology accessible and (relatively) simple and would like to get that message to as many students as possible. Thanks Emer!
this was so so helpful, thank you so much!
SO pleased, Lily.
Just so you know, www.biologycarol.co.uk exists, if you need more help x
I’m so glad I found this !!!
Woo! Hoo!
FYI all my videos are on my website www.biologycarol.co.uk - this is my attempt at making A level biology accessible regardless of any students family financial situation.
Thank you so much for this video! It is so useful! I’m in year 12 and I have an end of year assessment soon (online) so this has really refreshed my memory on the topic😊
Perfect😊. Go smash the assessment!
Very helpful! Really helped me with my VCE senior biology in Australia! Thankyou
Delighted! All the very best!
This is just brilliant
Thank you SO much for the encouragement, Ari 😊
love you carol you're amazing!!!
Lovin' the love😂
Seriously pleased I'm able to help, though!
May be worth checking out my website www.biologycarol.co.uk where ALL my videos are...
This was so helpful defiantly going to subscribe for more videos
😁
I assume you mean on my website...www.biologycarol.co.uk?
I will have covered the whole of AQA and OCR A syllabuses by end Jan. This is me seriously trying to make A level biology accessible to all students regardless of family income...
Thank you so much this is extremely useful and very well explained
SO pleased this helped! Do check out my website www.biologycarol.co.uk for my full complement of videos 😊
thank you for this brilliant lesson
Thank YOU!
Thank you very much for this video, I was really struggling to understand the process as a whole but this diagram makes all the individual bits of content come together perfectly. So glad I found this channel! Copied out the diagram and hung it on my bedroom wall haha.
P.S. Is there any chance that you could do a video on AQQ AS absorption of the products of digestion? I don’t really understand lipid absorption or glucose absorption.
Thank you!
Hi Sophie, thanks for the encouragement 😊 - even teachers need that ! I have digestion already down on my list of requests and I'm keeping a rough tally of numbers and its working its way to the top. Will try and do before Paper 1. Are you Yr 13?!
biology carol No problem, it’s just the truth. I have recommended your channel to my classmates too as I know they’ll benefit from it. :)
Nope, I am in year twelve. My AS mocks are week beginning June 4th so hopefully you’ll find some time before them for a digestion video (but if not, it’s no problem, I will just wrestle with textbook jargon.)
@@sophieahmed6015 Thank you - I really want this stuff to be accessible to anyone that needs it xx
Thank you, I really struggled to understand this during my lesson but I think I’ve gotten it now! I’m currently in year 12 and I have my bio exam in two days, wish me luck! :)
I hate ‘good luck’ but will say ‘ may you remember everything you’ve learnt and be able to spot what most of the questions are asking for’ x
The video was great, thanks. Just to clarify something here: to my belief, the cytotoxic T cells are produced by the T cells which have the receptor complimentary to the antigen of the original pathogen (correct me if I’m wrong). Thus, the cytotoxic T cells must contain the receptors which are complimentary to the pathogen’s antigen. If this is correct, how is it possible for the cytotoxic T cells to kill host cells? As the antigen on the host cell would be (to my understanding) different to that of the virus (the pathogen). Any response would be appreciated, thanks.
MY RESPONSE IN CAPITALS AND 😊!
The video was great, thanks 😊. Just to clarify something here: to my belief, the cytotoxic T cells are produced by the T cells which have the receptor complimentary COMPLEMENTARY ! COMPLIMENTARY MEANS SOMETHING DIFFERENT (DONT WORRY YOU WONT LOSE MARKS THROUGH) to the antigen of the original pathogen (correct me if I’m wrong THAT'S RIGHT). Thus, the cytotoxic T cells must contain NOT 'CONTAIN' - HAVE ON THEIR CELL SURFACE MEMBRANE the receptors which are complimentary to the pathogen’s antigen YEP. If this is correct, how is it possible for the cytotoxic T cells to kill host cells? BECAUSE HOST (BY THIS I MEAN THE BODY WHICH HAS BEEN INFECTED) CELLS WHICH ARE INFECTED WITH PATHOGENS (ESPECIALLY VIRUSES BUT COULD BE BACTERIA) PRESENT THE PATHOGEN'S ANTIGEN ON ITS CELL SURFACE MEMBRANE (JUST AS PHAGOCYTES DO) AND LIKE PHAGOCYTES, BECOME ANTIGEN PRESENTING CELLS. As the antigen on the host cell would be (to my understanding) different to that of the virus (the pathogen) NO - THE BODY'S CELLS DISPLAY THE ANTIGEN ON THEIR CSM. THIS BASICALLY ACTS AS A FLAG/SIGNAL TO THE CYTOTOXIC T CELLS TO COME AND DESTROY THE CELL (THEY 'TAKE ONE FOR THE TEAM').
WHY DO YOU THINK THE PATHOGEN'S ANTIGEN IS NOT THE SAME AS THAT PRESENTED ON THE PHAGOCYTE OR INFECTED CELL??
SORRY - USING CAPITALS FEELS LIKE IM SHOUTING AT YOU - I'm not !😂
biology carol thanks, that clarifies a lot. I guess, as the infected host cell would be caused by a virus (or bacteria, but when writing this I thought host cells were only infected/invaded by viruses), I didn’t think it would go through the process in which a phagocyte does to form an antigen presenting cell; I thought the virus would just infect the cell and continue to reproduce, with no formation of an antigen presenting cell on a host cell. However, as I now know the host body cell presents the pathogen’s antigens, it makes sense to me how the cytotoxic T cells are able to bind to the antigens of the antigen presenting cell (the host cell) and kill the cell and virus (or bacteria).
@@ShadowMan-wq7ib I think you've got it! you're right - infected host cells CAN be infected by some bacteria and definitely viruses and these cells become APCs. hopefully not to blow your brains too much, early cancer cells can also be APCs (our body's immune system deals with them before we even know - phew!) as well as (may be more obviously) cells of transplant organs - hence rejection.
You're a life saver, thankyou
Thank you. So pleased this has been useful!
Love the video. Few questions.
1) Does the T-helper cell turn into a cytotoxic killer cell? Or is the killer cell already there ? Or do they divide into killer cell?
2) can B-cells release antibodies on viruses in the blood stream?
3)why does each type of cell divide into more of them selves?
Other than those three, thank you for the video ! Really appreciate the explanation ☺️
The initially activated T helper cell divides by mitosis (clonal expansion) and differentiates into, among others, cytotoxic T cells (T killer cells or T K cells ). They are not already there, they’re made from the initial T H cell. Hope that helps x
Literally right before she said to put it at 1.5x speed I was doing it 😂
Absolutely!! I go for 2x, especially when listening to myself😂
Do you have to now about phagosome and phagolysosome for a level Bio?
Phagosomes - yes. not the term phagolysosome but you do need to know that lysosomes migrate towards and fuse with the phagosome, so that the digestive enzymes digest the pathogen. The fusion of the lysosome and a phagosome IS the phagolysosome but I don't believe you need that term.
@@biologycarol could you say phagoctic vacuole instead of phagosome?
Sorry - missed this! No - use the term phagosome!
Hi Miss, have you seen the 2023 papers? If you have what are your thoughts on them, what do you think the grade boundaries will be like?
I haven't seen the 2023 papers but heard about them!
The grade boundaries don't change that much from year to year (for AQA and OCR at least) and you can easily Google them. Not sure that's going to help you that much😬
Very helpful video. I think I spotted 1 mistake- at 5.31 you say polysaccharide when I think it should be polypeptide.
Thanks for this but no, I DID mean 'or polysaccharide'. Most antigens are proteins (polypeptides), but they can be glycoproteins or, indeed polysaccharides. The exam answer is nearly always 'Foreign protein that causes the production of antibodies'
Thank you this really helped
Really glad - made my day!
Very clear video! Thanks
So pleased - thank you.
Hi Carol, thank you so much for these videos they are saving me right now while preparing for mocks! Was wondering about the invlovement of Memory T cells, Killer T cells and Supressor T cells? Thank you!
You don't need to know details about those for AQA but...
Memory T cells stay in the blood and stimulate TH cells if the infection hits again
T Killer cells kill infected cells by punching a hole in their cell membrane
T Supressor cells stop the immune system attacking self cells in the war that is a pathogen infection.
My OCR immunity video covers these in more detail, but its on my website where my full complement of videos are. Do take a look www.biologycarol.co.uk 😊
@@biologycarol Amazing will do, thanks!
Hi there, thanks for this great video. Around the 13:00 mark, you talk about how the B cell needs to bind to antigen but also the Th cells. I know that B cells have antibodies complementary to the antigens, but do the B cells have receptors which bind specifically to the Th cells. Or is it like the process on the AQA a level 2nd edition textbook (curly haired boy holding a test tube) where the Antibodies of the B cells bind to the antigen, it then enters the cell by endocytosis and it is then presented on its surface. Then the Th cells bind to these presented antigens causing the B cell to be activated. Thank you
I’m really sorry- I’ve just realised that I missed this comment.
Your description is more detailed than mine and you are correct. I have simplified the description but I actually prefer the accuracy of yours.
Just so you know, I’ve never seen either of our levels of detail required for a mark in the exam. Hope that helps at least.
Thank youuu!
You're welcome!
This was an incredibly informative video. I do have one question about the activation of b cells. Are they required to bind to an antigen and also a specific helper t cell. The second 6 marker didnt specify that it had to bind to t cells.
Thank you x
And 'Yes' they are! Its jsut that that is not always a mark point in an exam Q - doesn't mean to say it isn't true though!
Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income. TH-cam pays very little (A level biology is a little niche!) and this is a way that I can continue to make content that's useful to students. The website includes a way of earning money off me and there's a freebie too 'How to improve your grade up to an A*’ - so grab that at least!
Thank you ,great video !
Thank YOU ❤️
Thank you so so much for this video!! You do not understand how helpful this is!! Would it be right to say then, phagocytosis happens first, presents the antigens on their surface, which t helper cells can bind to, of which B cells are activated by, stimulating the production of antibodies?
Absolutely - a level immunity in a nut shell!! Just remember that it is the memory cells that cause the immunity and the antibodies cause the pathogen to be destroyed (ie for you to recover from the disease). Well done!
Perfect!
Well, thank YOU😁
Thank you sooo much !!
SO pleased it helped!
Do u have a video on topic 4 aqa a level biology??
I have videos that cover the whole of AQA A level at www.biologycarol.co.uk. hope that might help😊
Thank you so much 😊
Hi - my teacher has taught this slightly differently: at 11:32 you say that binding of an antigen (presented on an APC) to a helper T-cell receptor then activates the T helper cell to differentiate into a cytotoxic T cell. My understanding is that T helper cells (CD4+) and cytotoxic T cells (CD8+) differentiate in the thymus, before they are released into the lymphatic system and thus exist as two distinct populations already. Activation of the t helper cell leads to it dividing by mitosis and helping to activate cytotoxic t cells. If I've got the wrong end of the stick please do say. Thank you!
That all sounds good to me. I am sticking to the level of
Detail required at A level. It’s great that you’ve been taught to a greater level of detail but if you’re taking a British A level that extra detail won’t get you more marks. Hope that puts your teaching in context x
@@biologycarol Brilliant, thank you for explaining! I was just slightly concerned I'd misunderstood something, phew! Thanks a lot, you're videos are really helpful! One other quick question about recombinant DNA if that's ok - after you've cut human DNA with restriction enzymes, how is the gene of interest then isolated? Is that when you use gel electrophoresis? But then if you don't know the sequence of the gene how do you isolate it? Or do you use gel electrophoresis after you've done the cloning? Thank you!!!
Hi Kalum! PCR would be used to duplicate the DNA sample, restriction enzymes would then be used to cut out the gene of interest. Assuming that you know the length of the gene of interest (which we do now as we can sequence genomes relatively easily), the gene can be separated from the rest of the DNA by gel electrophoresis because the latter technique separates by length of DNA and charge. Does that clarify how the techniques would e used together or is there something else that’s confusing you ? X
@@biologycarol Many thanks for your reply, much appreciated! Yes that clears it up, thank you. Out of interest, how would you seperate the band of interest if there is more than one DNA fragment of the same size? If REs cut at a specific site in the genome, presumably not every fragment generated will be of a different size? Hope that makes sense! Thanks!
Thanks
😁
Did u get the antigen and the anti body the wrong way round
Can you give me an idea of where on the video - INEED to check!!
Thus great
😁
Just in case you're in need of help on other topics, you might find my website worth a visit www.biologycarol.co.uk 😊 This is where all my videos are - each video including exam questions at the end. This is me on a mission to try and make A level biology accessible to ALL students regardless of family income. TH-cam pays very little (A level biology is a little niche!) and this is a way that I can continue to make content that's useful to students. The website includes a way of earning money off me and there's a freebie too 'How to improve your grade up to an A*’ - so grab that at least!
Good video but didn’t you forget to talk about lysosomes and lysozymes and phagosomes?
Thank you!
Didn’t forget, just decided to concentrate on the t and B cells bit which is where everyone gets confused!
Thank u.
Thank you for the thank you x
If it’s been useful, do check out www.biologycarol.co.uk where all my videos are.
WHATS THE DIFFERENCE BETWEEN THIS VDI AND THE OTHER IMMUNE RSPONSE ONE
The two exam boards AQA AND OCR have (rather unusually) very different emphases on what is required to be known for this topic. All the content is true (!) but I ended making 2 vids because of this. One vid constantly explaining what was different between the exam boards would have been too confusing.
Love you for this effort
I thought I was doomed 😭 tysm
Hope this means you’re not anymore😁
FYI www.biologycarol.co.uk exists - my attempt at making the whole of a level biology accessible to all students!
carol - I love u
I'm guessing it helped then...
There's way more on wwwbiologycarol.co.uk, just in case you're needing more love 😁❤
Please could you do one for gas exchange chapter 6 AQA
I've put it (or should i say them - think it might be more than 1...) on the list. They will happen, i just cant promise when. the request list's getting quite long!
@@biologycarol Thank you so much!!! Your hard work is much appreciated!!!
🧡🧡😊
😊
I now worship this woman
I love you carol
😂 Loving the adoration. Think it might be a little overstated though 😂. Really glad the videos are helpful 😊
5:42 isn’t a protein a polypeptide
No - but I see why you've asked!
The 'protein (or polysaccharide)' isn't me saying that another name for a protein is a polysaccharide; I'm saying that an antigen is nearly always a protein, but can sometimes be a polysaccharide. Does that make sense now? Hoping so xx
Haven't watched the video yet. Year 13 here...
Carol you have saved my life, will you marry me?
Lovin’ the appreciation 🤣🤣