The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

Edexcel IAL Biology Unit 4 June 2016

Scroll to see replies

Original post by Aimen.
Yea it's the only thing I know in immunity xD


So basically after the B cells form for the specific antigen, they differentiate to form Plasma cells. These are the ones that produce the antibodies. The antibodies are specific to the antigen and go to bind with it thereby forming and Antigen-Antibody Complex. These antibodies then round up or clump the bacteria together to prevent them from spreading. The phagocytes can now readily engulf this clump of bacteria and release lytic enzymes that breakdown the cell wall of the bacteria thereby causing water to move in. This causes the bacteria to swell and burst thereby killing it. Hope this wasn't too difficult. :smile:
Reply 41
Avatar for Aimen.
Aimen.
7
Original post by Sandy_Vega30
So basically after the B cells form for the specific antigen, they differentiate to form Plasma cells. These are the ones that produce the antibodies. The antibodies are specific to the antigen and go to bind with it thereby forming and Antigen-Antibody Complex. These antibodies then round up or clump the bacteria together to prevent them from spreading. The phagocytes can now readily engulf this clump of bacteria and release lytic enzymes that breakdown the cell wall of the bacteria thereby causing water to move in. This causes the bacteria to swell and burst thereby killing it. Hope this wasn't too difficult. :smile:


It wasn't difficult but kinda contradictory to my knowledge of immunity! (I know nothing at all)
I thought that phagocytosis has to do with body's non-specific responses and if non-specific ones fail then the body's specific response come to action (since B-cells are a part of specific responses so why are they in non-specific aswell?) :s-smilie:

Spoiler

Original post by Aimen.
It wasn't difficult but kinda contradictory to my knowledge of immunity! (I know nothing at all)
I thought that phagocytosis has to do with body's non-specific responses and if non-specific ones fail then the body's specific response come to action (since B-cells are a part of specific responses so why are they in non-specific aswell?) :s-smilie:

Spoiler



Think of phagocytes in non-specific response as the normal cops. When they see a thief (the bacteria) , they are gonna run after it and eliminate it. But the phagocytes in specific response and more like CSI and FBI. They need more help to identify the criminal (the bacteria) as it is not obvious. The role of the antibodies is to simply mark the foreign antigen which now alerts the phagocytes that it is the criminal (the bacteria to be destroyed). The antibodies themselves do not destroy the bacteria, help from phagocytes is needed. Phagocytosis is only a part of the specific response, so it doesn't technically belong to the specific response. Hope that makes sense. :smile:

Phagocytes have to be present in non- specific responses because they are the fastest mode of action.

Spoiler

(edited 7 years ago)
Reply 43
Avatar for Aimen.
Aimen.
7
Original post by Sandy_Vega30
Think of phagocytes in non-specific response as the normal cops. When they see a thief (the bacteria) , they are gonna run after it and eliminate it. But the phagocytes in specific response and more like CSI and FBI. They need more help to identify the criminal (the bacteria) as it is not obvious. The role of the antibodies is to simply mark the foreign antigen which now alerts the phagocytes that it is the criminal (the bacteria to be destroyed). The antibodies themselves do not destroy the bacteria, help from phagocytes is needed. Phagocytosis is only a part of the specific response, so it does technically belong to the specific response. Hope that makes sense. :smile:

Phagocytes have to be present in non- specific responses because they are the fastest mode of action.

Spoiler



OHAMMGEEE I DONNO HOW TO THANKYOU! I MEAN THAT WAS THE BEST EXPLANATION IN MY LIFE :party2:AND I JUST SEEM TO UNDERSTAND THE WHOLE IMMUNOLOGY THING! YOU'RE SUCH AN ANGEL XO
Original post by Aimen.
OHAMMGEEE I DONNO HOW TO THANKYOU! I MEAN THAT WAS THE BEST EXPLANATION IN MY LIFE :party2:AND I JUST SEEM TO UNDERSTAND THE WHOLE IMMUNOLOGY THING! YOU'RE SUCH AN ANGEL XO


Yay!!!!!!! :banana::cheers::angelwings:
Reply 45
Avatar for Aimen.
Aimen.
7
Original post by Sandy_Vega30
Yay!!!!!!! :banana::cheers::angelwings:



"You have already rated a post by this user recently!"
Original post by Aimen.
"You have already rated a post by this user recently!"


Aw, don't worry buddy. It's not about the reps. So long as you understand this **** it's all good. :h:
Original post by Sandy_Vega30
Think of phagocytes in non-specific response as the normal cops. When they see a thief (the bacteria) , they are gonna run after it and eliminate it. But the phagocytes in specific response and more like CSI and FBI. They need more help to identify the criminal (the bacteria) as it is not obvious. The role of the antibodies is to simply mark the foreign antigen which now alerts the phagocytes that it is the criminal (the bacteria to be destroyed). The antibodies themselves do not destroy the bacteria, help from phagocytes is needed. Phagocytosis is only a part of the specific response, so it doesn't technically belong to the specific response. Hope that makes sense. :smile:

Phagocytes have to be present in non- specific responses because they are the fastest mode of action.

Spoiler



Original post by Sandy_Vega30
So basically after the B cells form for the specific antigen, they differentiate to form Plasma cells. These are the ones that produce the antibodies. The antibodies are specific to the antigen and go to bind with it thereby forming and Antigen-Antibody Complex. These antibodies then round up or clump the bacteria together to prevent them from spreading. The phagocytes can now readily engulf this clump of bacteria and release lytic enzymes that breakdown the cell wall of the bacteria thereby causing water to move in. This causes the bacteria to swell and burst thereby killing it. Hope this wasn't too difficult. :smile:


These explanations actually saved my life! I don't understand the immunity chapter, it's just so confusing with the antigens, antibodies, t helper, t killer, b cells, phagocytes, macrophages etc etc:cry2::cry2: But this helped to sum it up, thanks a whole bunch!:colondollar:x
Reply 48
Avatar for Aimen.
Aimen.
7
Capture.PNG
Why is it a cistron? I thought it'd be a codon cuz I've never heard of cistron!
What is active and passive immunity?
Reply 50
Avatar for Aimen.
Aimen.
7
Original post by Annaaix_
What is active and passive immunity?


Active immunity and passive immunity are two types of immunity and both are further divided into natural and active immunity.
so, the basic difference between active and passive immunity is Active immunity is produced due to contact with pathogen whereas passive immunity is due to antibodies obtained from outside.
So, active immunity needs time as antibodies need to be made in response to antigens so responses are not immediate whereas passive immunity is immediate (for eg. when babies get antibodies from mothers in natural passive immunity)

Active immunity types are :
1. Natural active- When the person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response.
2.Artificial active- When a person is given vaccine; vaccine stimulates a primary response against the antigen without causing symptoms of the disease

Passive immunity types are:
1.Natural passive- During pregnancy, certain antibodies are passed from the maternal into the fetal bloodstream.
2.Artificial passive- A short-term immunization by the injection of antibodies.

Hope that makes sense! Ask me if you don't understand something! x)
Original post by Annaaix_
These explanations actually saved my life! I don't understand the immunity chapter, it's just so confusing with the antigens, antibodies, t helper, t killer, b cells, phagocytes, macrophages etc etc:cry2::cry2: But this helped to sum it up, thanks a whole bunch!:colondollar:x


No Problem! :biggrin:
Original post by Aimen.
Capture.PNG
Why is it a cistron? I thought it'd be a codon cuz I've never heard of cistron!


Although I am not able to gather much information about the cistron itself, from my research, a codon is a sequence of three base pairs on the DNA which is transcribed to give the corresponding mRNA NOT pre-mRNA,

A cistron therefore must be the sequence of triplets on a section of dna used to form a strand of pre mrna.

Spoiler

Reply 53
Avatar for Aimen.
Aimen.
7
Original post by Sandy_Vega30
Although I am not able to gather much information about the cistron itself, from my research, a codon is a sequence of three base pairs on the DNA which is transcribed to give the corresponding mRNA NOT pre-mRNA,

A cistron therefore must be the sequence of triplets on a section of dna used to form a strand of pre mrna.

Spoiler



But I guess that pre-mRNA is mRNA before post-transcriptional changes, so basically it's the same!
Might be an error in markscheme?
Original post by Aimen.
But I guess that pre-mRNA is mRNA before post-transcriptional changes, so basically it's the same!
Might be an error in markscheme?


From what I gathered, the cistron is a sequence of codons, so a few codons put together if that makes sense. I also read that one cistron carries the information for one single protein, which means multiple amino acids in a polypeptide chain. Not sure if I'm helping haha:tongue:
Original post by Annaaix_
From what I gathered, the cistron is a sequence of codons, so a few codons put together if that makes sense. I also read that one cistron carries the information for one single protein, which means multiple amino acids in a polypeptide chain. Not sure if I'm helping haha:tongue:


Yeah, a cistron is a single strand of DNA that is equivalent to a gene and that is involved in coding for a particular protein

Posted from TSR Mobile
(edited 7 years ago)
Original post by Aimen.
Capture.PNG
Why is it a cistron? I thought it'd be a codon cuz I've never heard of cistron!


Yeah it is a cistron.

Since the cistron is a single strand of DNA that is equivalent to a gene and that is involved in coding for a particular protein

So, the questions says that it's a sequence of triplets so it's a sequence of codons, okay then he says on one part of DNA which means a single strand of DNA (template strand) so it is the cistron

Posted from TSR Mobile
Reply 57
Avatar for Aimen.
Aimen.
7
How was the paper guys?
Original post by Aimen.
How was the paper guys?


actually so much better than i expected since I spent the last half hour before the exam trying to learn the whole immunity chapter and none of it was in it:biggrin:
Reply 59
Avatar for AvWOW
AvWOW
3
Hey guys. How did you find the paper today?

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you