Phagocytosis

Why are recognition molecules such as receptors typically proteins. Proteins can form an unlimited number of specific (tertiary) structures. Form a binding site for molecules that posses a complementary shape and/or are able to interact with exposed R-groups

Why are recognition molecules such as receptors typically proteins. Proteins can form an unlimited number of specific (tertiary) structures. Form a binding site for molecules that posses a complementary shape and/or are able to interact with exposed R-groups

Approximately 70% of all white blood cells are phagocytes. There are a number of different types of phagocyte that differ in terms of their appearance and where in the body they act. However, they all carry out phagocytosis in the same basic way. The most abundant, by far, are the neutrophils. Neutrophils have a multi-lobed nucleus and tend to be found in the blood. Different phagocytes, such as macrophages, can be found in other tissues like lymph and organs such as lungs and intestines.

Approximately 70% of all white blood cells are phagocytes. There are a number of different types of phagocyte that differ in terms of their appearance and where in the body they act. However, they all carry out phagocytosis in the same basic way. The most abundant, by far, are the neutrophils. Neutrophils have a multi-lobed nucleus and tend to be found in the blood. Different phagocytes, such as macrophages, can be found in other tissues like lymph and organs such as lungs and intestines.

Role of an Antigen-Presenting Cell 1) Phagocytosis of enemy cell (antigen) 2) Fusion of lysosome and phagosome 3) Enzymes start to degrade enemy cell 4) Enemy cell broken into small fragments 5) Fragments of antigen presented on APC surface 6) Leftover fragments released by exocytosis

Role of an Antigen-Presenting Cell 1) Phagocytosis of enemy cell (antigen) 2) Fusion of lysosome and phagosome 3) Enzymes start to degrade enemy cell 4) Enemy cell broken into small fragments 5) Fragments of antigen presented on APC surface 6) Leftover fragments released by exocytosis

Antigen presentation - Neutrophils can engulf and destroy a pathogen in about 10 minutes - Macrophages take longer because they combine cell surface antigens of the pathogen with special glycoproteins called the major histocompatibility complex (MHC) - The MHC carriers an antigen to the macrophages cell surface membrane, where it is externally displayed. In this way, macrophages become antigen presenting cells (APC) that are capable of stimulating cells involved in the adaptive immune response.

Antigen presentation - Neutrophils can engulf and destroy a pathogen in about 10 minutes - Macrophages take longer because they combine cell surface antigens of the pathogen with special glycoproteins called the major histocompatibility complex (MHC) - The MHC carriers an antigen to the macrophages cell surface membrane, where it is externally displayed. In this way, macrophages become antigen presenting cells (APC) that are capable of stimulating cells involved in the adaptive immune response

By what mechanisms might the soluble products of digestion be absorbed into the cytoplasm across the membrane of the phagolysosome. Facilitated Diffusion, Active Transport, Diffusion (Fatty Acid)

By what mechanisms might the soluble products of digestion be absorbed into the cytoplasm across the membrane of the phagolysosome. Facilitated Diffusion, Active Transport, Diffusion (Fatty Acid)

Once bound to the pathogen, for example a bacterium, the following sequence of events takes place: 1) The plasma membrane extends around the bacterium engulfing it (a similar process to endocytosis) 2) The bacterium becomes enveloped in a vesicle formed from the plasma membrane of the phagocyte called a phagosome 3) Organelles in the cytoplasm of the phagocyte called lysosomes fuse with the phagosome to form a phagolysosome 4) The hydrolytic enzymes contained in the lysosomes digest the molecules of the bacterium destroying it 5) The soluble products of digestion are absorbed into the cytoplasm of the phagocyte 6) Any undigested materials are released from the cell by exocytosis. (This debris may serve to attract more phagocytes to the site of infection)

Once bound to the pathogen, for example a bacterium, the following sequence of events takes place: 1) The plasma membrane extends around the bacterium engulfing it (a similar process to endocytosis) 2) The bacterium becomes enveloped in a vesicle formed from the plasma membrane of the phagocyte called a phagosome 3) Organelles in the cytoplasm of the phagocyte called lysosomes fuse with the phagosome to form a phagolysosome 4) The hydrolytic enzymes contained in the lysosomes digest the molecules of the bacterium destroying it 5) The soluble products of digestion are absorbed into the cytoplasm of the phagocyte 6) Any undigested materials are released from the cell by exocytosis. (This debris may serve to attract more phagocytes to the site of infection)

Suggest 3 different types of enzyme that would be found in a lysosome and give word equations for the hydrolysis reactions that they catalyse. Carbohydrase; Glycogen -> Glucose Lipase; Lipids -> fatty acids + glycerol Protease; Proteins -> Amino Acids

Suggest 3 different types of enzyme that would be found in a lysosome and give word equations for the hydrolysis reactions that they catalyse. Carbohydrase; Glycogen -> Glucose Lipase; Lipids -> fatty acids + glycerol Protease; Proteins -> Amino Acids

Phagocytosis are attracted to pathogens by chemical signals (cytokines) produced by the pathogen or from host cells, including mast cells and other phagocytes, at the site of infection. The phagocytes must then be able to recognise the pathogen in order to be able to destroy it. In order to do so, phagocytes possess receptors in their plasma membranes that can bind to foreign (non-self) molecules, or antigens, found on the surface of pathogens. Bacterial pathogens are made more conspicuous to phagocytes if they have first been coated, or 'tagged', by opsonins: chemicals produced by the body, such as antibodies and other proteins, to which phagocytes can bind via complementary receptors.

Phagocytosis are attracted to pathogens by chemical signals (cytokines) produced by the pathogen or from host cells, including mast cells and other phagocytes, at the site of infection. The phagocytes must then be able to recognise the pathogen in order to be able to destroy it. In order to do so, phagocytes possess receptors in their plasma membranes that can bind to foreign (non-self) molecules, or antigens, found on the surface of pathogens. Bacterial pathogens are made more conspicuous to phagocytes if they have first been coated, or 'tagged', by opsonins: chemicals produced by the body, such as antibodies and other proteins, to which phagocytes can bind via complementary receptors.

Phagocytosis is the process by which white blood cells, known as phagocytes, engulf and digest cells - thereby destroying them. These cells may be pathogens such a bacteria. Therefore, phagocytosis is one of the ways by which the immune system can protect the body from infection

Phagocytosis is the process by which white blood cells, known as phagocytes, engulf and digest cells - thereby destroying them. These cells may be pathogens such a bacteria. Therefore, phagocytosis is one of the ways by which the immune system can protect the body from infection