How does an organism know the sequence of a protein?

In summary: The white cell is the immune system. It recognizes the foreign protein and attacks it. The immune system is a system of white blood cells that recognize and attack foreign proteins. When a foreign protein is introduced into a mouse or rabbit, the immune system attacks the protein by producing antibodies which specifically recognize the protein. The sequence of the protein is known by the body so that an antibody specific to that non-self protein can be manufactured.
  • #1
hivesaeed4
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When a foreign protein is introduced in a rabbit or a mouse, its immune system attacks the protein by antibodies which specifically recognize the protein. How does the body know the sequence of the protein such that it manufactes an antibody which will specifically target that non-self protein.
 
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  • #2
hivesaeed4 said:
When a foreign protein is introduced in a rabbit or a mouse, its immune system attacks the protein by antibodies which specifically recognize the protein. How does the body know the sequence of the protein such that it manufactes an antibody which will specifically target that non-self protein.
Lymphocytes (white blood cells) are organized in a system called the immune system. Lymphocytes recognize antigens, make antibodies specific to the antigens, and eat anything the antibodies stick to. The T cells do the initial recognition of the foreign body.
The system is complicated. I have been trying to understand it. As I understand it as follows. Others correct me if I make a mistake (please).
The thymus produces T cells. While the body is in an early embryo stage, the thymus “learns” to recognize all proteins that are part of the body. All proteins the thymus comes into contact with while an embryo becomes recognized as “self”. The thymus creates T cells with random sequences, where the random sequences exclude the initial set of proteins that were not part of the embryo.
T cells are produced by the thymus. Each T-cell has a set of antibodies with randomly generated sequences. T-cells randomly come into contact with other cells. If the antigen in the other cell matches an antibody in the T-cell, the T-cell eats the other cell. The T cell makes copies of the antigen. The antigen of the consumed cell sticks out the surface of the T cell. The T cell thus “presents” the antigen of the foreign body.
Whenever a B cell or other lymphocyte comes into contact with the activated T cell, it becomes activated against the specific antigen. The B cells pass the message along. The body treats the protein sequence described in the B cell message as an invader. The body is sensitized to the attacking protein.

Some links and relevant quotes.
http://en.wikipedia.org/wiki/Immune_system
“Killer T cells are a sub-group of T cells that kill cells that are infected with viruses (and other pathogens), or are otherwise damaged or dysfunctional.[51] As with B cells, each type of T cell recognises a different antigen. Killer T cells are activated when their T cell receptor (TCR) binds to this specific antigen in a complex with the MHC Class I receptor of another cell.”

http://en.wikipedia.org/wiki/Lymphocyte
“A lymphocyte is a type of white blood cell in the vertebrate immune system.[1]
Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells (NK cells). Small lymphocytes consist of T cells and B cells.”http://en.wikipedia.org/wiki/B_cell
“B cells are lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response, which is governed by T cells). B cells are an essential component of the adaptive immune system. B cells, which are the precursors of plasma cells, are characterized by the presence of a B-cell receptor able to bind specifically an antigen. Their principal functions are to make antibodies against antigens, perform the role of antigen-presenting cells (APCs) and eventually develop into memory B cells after activation by antigen interaction. Recently, a new, suppressive function of B cells has been discovered.”
 
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Thanks.
 
  • #4
hivesaeed4 said:
Thanks.

In this picture, the thymus presents a sign up sheet for embryonic proteins. The mothers placenta is the gate keeper. The proteins that reach the thymus are given stickers for parking space. Once the animals is born, the "sign up sheet" is taken away. No more stickers for parking space The off springs T cells become the gate keepers. Any protein that enters the offspring after birth, who doesn't have a sticker for parking space, has a good chance of being towed away by a white cell.
 
  • #5


The process of creating antibodies to target a specific protein is known as the immune response. The immune response is a highly complex and sophisticated system that involves multiple components working together to protect the body from foreign substances, such as proteins from a virus or bacteria.

In order for the immune system to produce antibodies against a specific protein, it must first recognize and identify the protein as a foreign invader. This recognition is achieved through a process called antigen presentation. Antigens are molecules on the surface of a foreign substance that can be recognized by the immune system.

When a foreign protein is introduced into the body, specialized cells called antigen-presenting cells (APCs) identify the protein and break it down into smaller fragments. These fragments are then presented on the surface of the APCs, where they can be recognized by other immune cells, specifically B cells.

B cells are a type of white blood cell that are responsible for producing antibodies. When a B cell encounters an antigen that matches its specific receptor, it becomes activated and begins to divide and multiply. This process, known as clonal expansion, produces a large number of B cells that are all specific for the same antigen.

During this process, the B cells also undergo a process called somatic hypermutation, where their genetic material is altered to create a more diverse pool of B cells with slightly different receptors. This increases the chances of finding a B cell with a receptor that can bind tightly to the foreign protein.

Once a B cell with a matching receptor is found, it begins to produce large quantities of antibodies that are specific for the foreign protein. These antibodies can then bind to the foreign protein and mark it for destruction by other immune cells.

In summary, the body knows the sequence of a protein through the process of antigen presentation, B cell activation and clonal expansion, and somatic hypermutation. These processes allow the immune system to produce a diverse and specific pool of antibodies to target and eliminate foreign proteins.
 

1. How does an organism know the sequence of a protein?

An organism knows the sequence of a protein through a process called protein synthesis. This process involves the transcription of DNA into mRNA and the translation of mRNA into a sequence of amino acids, which make up proteins.

2. What is the role of DNA in determining the sequence of a protein?

DNA contains the genetic information that determines the sequence of amino acids in a protein. This information is used to create mRNA, which then directs the assembly of amino acids into a specific protein sequence.

3. How does the genetic code dictate the sequence of a protein?

The genetic code is a set of rules that determine how the sequence of nucleotides in DNA is translated into a sequence of amino acids in a protein. Each set of three nucleotides, called a codon, codes for a specific amino acid, allowing for the correct sequence to be determined.

4. Can the sequence of a protein change in an organism?

Yes, the sequence of a protein can change through mutations in the DNA. Mutations can alter the sequence of nucleotides, which can then lead to changes in the sequence of amino acids in a protein. These changes can have both positive and negative effects on an organism's function.

5. How does an organism ensure the accuracy of the protein sequence?

An organism has various mechanisms in place to ensure the accuracy of the protein sequence. This includes proofreading and repair mechanisms during DNA replication, as well as quality control processes during protein synthesis. Additionally, mutations that result in significant changes to the protein sequence are often eliminated through natural selection.

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