3.2.4 Cell Recognition and The Immune System Flashcards
Antigens are molecules that trigger an immune response by…
Lymphocytes
Pathogens are…that cause disease
Agents
(We can’t say microorganisms as viruses aren’t organisms as they are acellular)
Process of phagocytosis (how phagocytes destroy pathogens)
1) Phagocyte membrane surrounds pathogen and engulfs it
2) A vesicle (phagosome) is formed inside the phagocyte which contains the pathogen
3) Lysosomes in the cytoplasm fuse with the vesicle phagosome (to form a phagolysosome) and release hydrolytic enzymes
4) The hydrolytic enzymes hydrolyse the pathogen and destroy it
Antigens are molecules that trigger an immune response by lymphocytes and can be found on the cell surface membranes of … , …. and…
Antigens can also be toxins in solution
Pathogens
Foreign cells (cells from other organisms of the same species- cells that aren’t your own body cells)
Abnormal body cells (e.g cells in uncontrolled cell division/ cancer cells)
True or false, antigens are only ever found on the cell surface membrane of cells and nowhere else
False
Antigens can be toxins in solution
Is a non- specific immune response immediate (quick) or slow
Immediate/ quick
As the response is the same no matter what the pathogen is. The phagocytes just engulf the pathogen and destroy it, no matter what it is and any phagocyte can engulf and destroy any pathogen
Is phagocytosis a specific or non specific immune response
Non specific
(As any phagocyte can engulf and destroys any pathogen no matter what the pathogen is)
Are phagocytes involved in specific or non specific immune responses
Non specific
(Any phagocyte can digest and engulf any pathogen)
Are T lymphocytes and B lymphocytes involved in a specific or non specific immune response
Specific
As the response is specific to each pathogen
Antibodies are soluble proteins and are made up of chains of amino acids. Each antibody (protein) is made up of …(how many) polypeptide chains
4
Each antibody has a …region with a unique tertiary structure (due to a different specific sequence of amino acids). This…region is complementary to one specific antigen
Variable
Each antibody has a variable region with a unique …..
Tertiary structure
Antibodies (the variable region of them which have a unique tertiary structure due to a specific sequence of amino acids) are…to the antigen
Complementary
True or false, antibodies are complementary to the antigen
True
Each antibody has a different variable region (a unique tertiary structure due to a specific sequence of amino acids)
.
.
Antibodies are made up of 4 polypeptide chains which are joined together by ….and stabilise the protein (as antibodies are proteins)
Disulfide bridges
Where on the antibody is the binding site (to bind to the antigen)
The variable region (where each antibody has a unique tertiary structure that’s complementary to a specific antigen)
All antibodies have the same…regions but they have different variable regions (the variable regions are the binding site where the antibody binds to the antigen)
Constant
An antibody binds to an antigen to form an…
Antigen- antibody complex
Why can an antibody bind to 2 antigens at the same time
It has 2 binding sites
True or false, an antigen is the same thing as a pathogen
False
Antigens are molecules found on the cell surface membrane of the pathogen
The immune system initiates 2 types of response: a humoral response and a …response
Cellular (cell mediated)
The immune system initiates 2 types of response: a …response and a cellular response
Humoral
When lymphocytes attack your own cells (self cells) it causes symptoms of an..disease
Autoimmune
Types of molecules that antigens can be include proteins,…. and …
Glycolipids
Glycoproteins
What are lysozymes
The hydrolytic enzymes released by lysosomes (which hydrolyse and destroy the pathogen in phagocytosis)
During phagocytosis the lysosomes release hydrolytic enzymes called…
Lysozymes
The 2 types of specific immune responses are… and….
Cell mediated
Humoral
True or false B cells and B lymphocytes are the same thing and T cells and T lymphocytes are the same thing
True
Lymphocytes are a type of white blood cell
True or false, phagocytes are antigen presenting cells (APCs)
True
As after phagocytosis, they present the processed antigens on the MHC on their cell surface membrane
Process of humoral response (involves B cells)
1) Pathogen undergoes phagocytosis by a phagocyte (antigen presenting cell (APC)) and the phagocyte presents the processed antigens on the MHC of its cell surface membrane
2) A specific T helper cell with receptors complementary to the presented antigens bind to the presented antigens which activates the T helper cell
3) The T helper cell releases cytokines which triggers it to undergo mitosis to form an identical clone of T helper cells
4)These activated T helper cells activate a specific B cell to undergo mitosis and differentiate into plasma cells and memory cells.
5) The plasma cells release antibodies specific and complementary to the antigen (primary response)
6) The memory cells stay in circulation to then differentiate into more plasma cells and memory cells if there is a 2nd incidence of infection of the same pathogen (secondary response)
How do the activated T cells activate a specific B cell?
Whilst phagocytes have engulfed the pathogen by phagocytosis and then processed and displayed the antigens on its cell surface membrane, B cells that have antibodies complementary to the antigens on that pathogen bind to the antigen then engulf the pathogen by endocytosis, process the antigens and present them on its cell surface membrane.
The activated T helper cells (that have been activated by the phagocyte) come to these B cells and their receptors bind to the complementary antigens being presented
The process of binding activates the T helper cells to release cytokines which activates the B cell to undergo mitosis and differentiate into plasma cells and memory cells
In the humoral response, B cells differentiate into …cells and…cells
Plasma
Memory
In the humoral response, B cells differentiate into plasma cells and memory cells
Which cells are responsible for the primary response
Plasma cells
(They secrete the specific antibodies into the bodily fluids straight away)
In the humoral response, B cells differentiate into plasma cells and memory cells.
Which cells are involved in the secondary response
Memory cells
They stay in circulation so that if there is a 2nd infection of the same pathogen, they can quickly differentiate into plasma cells and memory cells for the antibodies that are specific to the antigen to be released straight away and for the pathogen to be destroyed before you develop symptoms (this makes you immune)
When phagocytes/ B cells present the processed antigens on their cell surface membrane, what does the antigen bind to
MHC
Antigen presenting cells (APCs) are any cells that present a…on their cell surface membrane
Non-self antigen (an antigen from an abnormal body cell/ pathogen/ cell from another organism of the same species)
The ‘Cell- mediated’ response means that T cells only respond to antigens that are where
Being presented on the cell surface membrane of APCs
(Not antigens detached from cells e.g in the blood (in bodily fluids))
A vaccine is a …form of the pathogen that contains …but is incapable of triggering …
Weakened (attenuated)
Antigens
Disease
….T cells bind to antigens on abnormal body cells (cancer cells) and virally infected cells and destroy them by releasing perforin which creates holes in the cell membrane (punctures it)
Cytotoxic
When cytotoxic T cells bind to antigens on abnormal body cells (cancer cells) and vitally infected cells they release ….which is a protein that creates holes in the cell membrane and destroys the cell
Perforin
HIV stands for…
Human Immunodeficiency Virus
HIV has…as its genetic material
RNA
(Viruses either have DNA or RNA as their genetic material)
HIV has …enzymes
Reverse transcriptase
5 key structural features of HIV
Capsid
RNA
Attachment proteins
Lipid envelope
Reverse transcriptase enzymes
The attachment proteins on HIV bind to…receptor proteins on T helper cells
CD4
The attachment proteins on HIV bind to CD4 receptor proteins on…cells
T helper
If you’re HIV positive, it means that you have….for HIV
Antibodies
For HIV, the host cell is…cells
T helper
Where does HIV get its lipid envelope from
The host cell
The core of the HIV (what’s contained within the capsid) contains… and…
RNA
Reverse transcriptase enzymes
The core of the HIV (what’s contained within the capsid) contains… and…
RNA
Reverse transcriptase enzymes
The attachment proteins on HIV are called…
gp120
Process of how HIV particles multiply when inside a human
1) The attachment proteins on HIV bind to the complementary CD4 receptor proteins on T helper cells
2) The RNA and reverse transcriptase enzymes from HIV enter the T helper cell (host cell)
3) The reverse transcriptase enzymes copy the RNA from HIV into DNA (this process is called reverse transcription)
4) The DNA copy is inserted into the chromosomes of the T helper cell
5) The DNA copy is transcribed into HIV mRNA (an RNA copy of the DNA)
6) The viral mRNA is translated into viral proteins
7) The viral proteins are assembled into more HIV particles
8) The viral particles all burst out of the T helper cell which destroys it
Symptoms of HIV (before it has developed into AIDS)
Flu like symptoms
Once inside the host T helper cell, the viral DNA is transcribed into …which is then translated into viral proteins
mRNA
Once inside the host T helper cell, viral DNA is…into mRNA which is then…into viral proteins
Transcribed
Translated
In the T helper cell once a DNA copy has been made (the HIV reverse transcriptase enzymes produce a DNA copy of the RNA from the HIV particle) which comes first out of transcription and translation
Transcription (the viral DNA is transcribed into mRNA)
After this transcription the mRNA is translated into viral proteins which are used to produce more HIV particles
Why does HIV infecting and destroying T Helper cells mean that the humoral and cell-mediated immune response can no longer work effectively
They require the T helper cells for the B cells and Cytotoxic T cells to be activated
But seeing as a large number of T helper cells have been destroyed once they’re infected by the HIV, there is a very low number of T helper cells left to be able to do the activation (so very few B cells can differentiate into plasma cells to release specific antibodies and very few cytotoxic T cells can be activated to destroy virally infected cells/ cancer cells)
Opportunistic infection meaning
Infections that occur more often and are more severe in someone with a weakened immune system (e.g someone with AIDS as they have a very low number of T helper cells)
Someone with AIDs is vulnerable to…infections and….
Opportunistic (these are infections that occur more often and are more severe in someone with a weakened immune system compared to someone with a healthy immune system)
Cancer (as there are very few T helper cells to activate the cytotoxic T cells to be able to destroy the cancer cells)
Why does someone with AIDS produce less antibodies than normal
The HIV decreases the number of T helper cells so fewer B cells undergo mitosis and differentiate into plasma cells (which are what produce the antibodies)
4 stages of how HIV replicates once inside the T helper cell
1) Reverse transcriptase enzymes convert RNA into DNA
2) The DNA is inserted into T helper cell chromosomes
3) The DNA is transcribed into mRNA
4) The mRNA is translated into viral proteins which are assembled into more HIV particles
Antigenic variation meaning
Pathogens modify their surface proteins.
This means that antibodies specific to the original antigen are no longer complementary to the mutated antigen and can no longer bind. Therefore the secondary immune response doesn’t work
Antigenic variation occurs when genes coding for…mutate
Antigen proteins on the surface of a pathogen
Antigen variation is to do with the antigens changing shape that are found on the surface of…
Pathogens
Antigen variation occurs when…mutate
The genes coding for the antigen protein on the surface of the pathogen
What happens when genes coding for antigen proteins on the surface of a pathogen mutates
The change in base sequence can cause a change in the amino acids sequence of the protein which changes the tertiary structure of the protein (so it’s no longer complementary to the antibodies that have been produced against it)
What is a monoclonal antibody
An antibody produced from a cloned B cell
(They are antibodies that all have the same tertiary structure as each other)
Monoclonal antibodies can be used to treat cancer as it can carry a … to a specific antigen on the cancer cell. The complementary monoclonal antibody then binds to the specific antigen and the drug destroys the cancer cell
Drug (the drug is attached to the constant region of the antibody. The antibody has been produced by injecting a mouse with the antigen from the cancer cell)
True or false, antibodies destroy the pathogen/ cancer cell/ foreign cell once they’ve bound to them
False
It’s the phagocyte that then comes and destroys it by phagocytosis
When antibodies bind to the antigen it leads to agglutination (clumping) of the cells/ pathogens which makes it easier for pathogens to locate and destroy them
When a pathogen is coated in antibodies it makes the pathogen more appetising for the phagocyte to engulf which is known as enhanced phagocytosis
What is agglutination
Where cells/ pathogens clump together when they have antibodies bound to them which makes it easier for phagocytes to locate and destroy them
What is enhanced phagocytosis
When a pathogen is coated in antibodies it makes the pathogen more appetising for the phagocytes to engulf
What is it called when a pathogen is coated in antibodies which makes the pathogen more appetising for phagocytes to engulf
Enhanced phagocytosis
What is it called when cells/ pathogens that are bound to antibodies clump together which makes it easier for phagocytes to locate and destroy them
Agglutination
Another word for the specific immune response is the…Immune response which includes the cell mediated response and humoral response
Adaptive
True or false, the specific immune response and adaptive immune response are the same thing
True
It includes the humoral response and cell mediated response
Another word for the non specific immune response is the…immune response
Innate
This includes phagocytosis and physical barriers e.g the skin
What is passive immunity
A type of immunity where you don’t produce the antibodies yourself (you aren’t exposed to the antigen) but instead are injected them/ they are passed on to the baby from the mother via breastfeeding (the antibodies are introduced from outside your body)
You don’t have any long term protection as no memory cells are produced- instead it provides short term protection as the antibodies are broken down
The protection provided is immediate
Does passive immunity provide short term or long term protection/ immunity
Short term
As you aren’t exposed to the antigen so it doesn’t cause memory cells to be produced, instead the antibodies are introduced from outside the body and break down
In Passive immunity, the antibodies are introduced from where
Outside your body e.g through an injection of antibodies/ into the baby through breastfeeding
2 examples of how antibodies are introduced into the body without our body producing them ourselves (this is passive immunity)
Through an injection containing the antibodies
Through breastfeeding (they are passed onto the baby)
Active immunity occurs when you are exposed to the…
Antigen
(This then causes the humoral and cell-mediated response to occur so provides long term protection as memory cells are produced in the process)
Out of active and passive immunity, which type involves memory cells
Active (as you’re body is exposed to the antigen which triggers the humoral and cell- mediated response and in the humoral response memory cells are produced)
However in passive immunity the antibodies have come from an injection/ breastfeeding so it doesn’t involve the humoral or cell- mediated response
Natural vs artificial active immunity
Natural- your body is infected with the antigen from the pathogen
Artificial- a weakened version of the pathogen containing the antigens is injected into your body (vaccine)
Why does active immunity take time to develop
Once you have been exposed to the antigen, your T helper cells need to be activated, then your B cells need to be activated before they can undergo mitosis and differentiate into plasma cells which produce the specific antibody
So it takes time for the antibodies to be produced
When someone is given a vaccine, how does this lead you to antibodies being produced against that specific pathogen
The vaccine contains antigens from the pathogen
Phagocytes present the antigen on their surface
T helper cells with complementary receptor protein bind to the presented antigen on the phagocyte (APC)
T helper cell stimulates a specific B cell
B cell with a complementary antibody on its surface divides by mitosis and differentiates into memory cells and plasma cells
Plasma cells secrete a large number of specific antibodies that are complementary to the antigen
Features of a successful vaccination programme
Enough trained staff available for administration
Side effects are rare
Enough people can be vaccinated in order to achieve herd immunity
Cold storage and transportation is manageable
Large enough amounts can be produced so that the most vulnerable people can be vaccinated at a reasonable cost
