Cell recognition and immune system

• Whats a lymphocyte?

  Types of white blood cells in the immune system
• What can lymphocytes do?

  Recognise self cells (our own cells) and non-self cells
• What can lymphocytes identify?

  Toxins

  Pathogens

  Cells from other humans

  Abnormal body cells; cancer
• Whats an antigen?

  A protein in the cell surface membrane that triggers an immune response
• How do lymphocytes recognise antigens?

  complementary receptors that bind to antigens.
• How many antigens can one lymphocyte recognise?

  One specific antigen
• How do phagocytes recognise pathogens?

  Have receptors that are complementary to all pathogens, triggering an immune response
• Why do phagocytes fall under the non-specific immune system?

  Because they can recognise all pathogens
• What is the process that phagocytes carry out?

  Phagocytosis
• what is the process of phagocytosis

  As a pathogen release toxins, it catches the attention of a phagocyte

  moving up a concentration gradient

  The phagocyte binds to the pathogens complementary antigen

  the phagocyte changes shape, engulfing the pathogen

  the pathogen is trapped in a sac-like structure called a vesicle

  A vesicle containing a pathogen; phagosome

  Lysosomes move to it, releasing lysozyme breaking down the pathogen by catalysing a hydrolysis reaction, the cytoplasm absorbs soluble products, any other stuff it couldnt absorbed is exited out the cell
• What is the enzyme in a lysosome

  Lysozyme
• Where are B lymphocytes found?

  Bone marrow
• Where are t lymphocytes matured in?

  Thymus
• When a naive B cell binds to a pathogen, what happens?

  Internalises the pathogen, keeps a hold on the antigens and presents it on its surface

  A complementary T cell binds to it
• What leads to cloning of a B cell?

  As the T cell attaches onto the complementary antigen on the B cell, it stimulates it by releasing chemicals, leading to cloning
• T cells which help stimulate B cells are what type of t cell?

  Helper T cells
• What does a cloned B cell differentiate to?

  Plasma cells or memory cells
• What do plasma cells secrete?

  Antibodies
• How many chains does an antibody have?

  4
• Amino acids within a chain are held together by what?

  Peptide bonds
• Structure of an antibody

  
• A - Antigen binding site

  B - constant reigon

  C- Disulfide bridge

  D - light chain

  
• Whats an antibody?

  A protein secreated by plasma cells, produced by naive b cells in response to the presence of a specific antigen
• How long does a plasma cell survive for?

  A few days
• What are monoclonal antibodies?

  Antibodies with the same teritary structure, produced from cloned B cells
• When an antibody binds to a antigen, what is that called?

  Antigen-antibody complex
• How many antigens can 1 antibody bind to at the same time?

  2
• Define agglutination

  Antibodies bind to antigens on pathogens, causing them to clump together.
• What happens when a memory B cell encounters an antigen?

  Receptors bind to the antigen, internalising it and presenting it on its surface

  A helper t cell binds to it stimulating the memory b cell to clone itself
• What can cloned memory B cells differentiate to?

  Plasma cells or memory B cells
• What is the difference between memory b cells and naive b cells?

  Memory B cells remember antigens, so they are much quicker that you wouldnt even get any symptoms.

  Memory B cells can produce a greater concentration of antibodies in the second response as more plasma cells are formed
• If antigens can mutate, what does this lead to?

  Memory B cells being useless, they cannot bind to their antigen

  Naive b cells must respond
• Whem memory B cells clone themselves to produce plasma cells or memory b cells, what response is this?

  Secondary response
• The primary + secondary response together is called what?

  Humoral response
• Identify why monoclonal antibodies detect the same antigen.

  They all have the same teritary structure and Their binding sites are complementary to the same antigen
• Describe how antibodies lead to the destruction of a pathogen.

  Antibodies bind to complementary antigens on the surface of the pathogen, forming antibody-antigen complexes.This causes pathogens to clump together in a process called agglutination, which makes it easier for phagocytes to engulf and destroy pathogens.
• What do T-cells bind to?

  Antigen presenting cells
• Name some sntigen presenting cells

  B cells

  Phagocytes

  Own body cells (virus infected)
• At the final stage of phagocytosis, some of the pathogens remains are processed and presented on the cells surface
• What are the 2 types of t-cells

  Helper t cell

  Cytotoxic t cells