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There are numerous other AMPs throughout the body. The characteristics of a few of the more significant AMPs are summarized in [link] .

Characteristics of Selected Antimicrobial Peptides (AMPs)
AMP Secreted by Body site Pathogens inhibited Mode of action
Bacteriocins Resident microbiota Gastrointestinal tract Bacteria Disrupt membrane
Cathelicidin Epithelial cells, macrophages, and other cell types Skin Bacteria and fungi Disrupts membrane
Defensins Epithelial cells, macrophages, neutrophils Throughout the body Fungi, bacteria, and many viruses Disrupt membrane
Dermicidin Sweat glands Skin Bacteria and fungi Disrupts membrane integrity and ion channels
Histatins Salivary glands Oral cavity Fungi Disrupt intracellular function
  • Why are antimicrobial peptides (AMPs) considered nonspecific defenses?

Plasma protein mediators

Many nonspecific innate immune factors are found in plasma , the fluid portion of blood. Plasma contains electrolytes, sugars, lipids, and proteins, each of which helps to maintain homeostasis (i.e., stable internal body functioning), and contains the proteins involved in the clotting of blood. Additional proteins found in blood plasma, such as acute-phase proteins, complement proteins, and cytokines, are involved in the nonspecific innate immune response.

Plasma versus serum

There are two terms for the fluid portion of blood: plasma and serum. How do they differ if they are both fluid and lack cells? The fluid portion of blood left over after coagulation (blood cell clotting) has taken place is serum . Although molecules such as many vitamins, electrolytes, certain sugars, complement proteins, and antibodies are still present in serum, clotting factors are largely depleted. Plasma, conversely, still contains all the clotting elements. To obtain plasma from blood, an anticoagulant must be used to prevent clotting. Examples of anticoagulants include heparin and ethylene diamine tetraacetic acid (EDTA). Because clotting is inhibited, once obtained, the sample must be gently spun down in a centrifuge. The heavier, denser blood cells form a pellet at the bottom of a centrifuge tube, while the fluid plasma portion, which is lighter and less dense, remains above the cell pellet.

Acute-phase proteins

The acute-phase proteins are another class of antimicrobial mediators. Acute-phase proteins are primarily produced in the liver and secreted into the blood in response to inflammatory molecules from the immune system. Examples of acute-phase proteins include C-reactive protein , serum amyloid A , ferritin , transferrin , fibrinogen , and mannose-binding lectin . Each of these proteins has a different chemical structure and inhibits or destroys microbes in some way ( [link] ).

Some Acute-Phase Proteins and Their Functions
C-reactive protein Coats bacteria (opsonization), preparing them for ingestion by phagocytes
Serum amyloid A
Ferritin Bind and sequester iron, thereby inhibiting the growth of pathogens
Transferrin
Fibrinogen Involved in formation of blood clots that trap bacterial pathogens
Mannose-binding lectin Activates complement cascade

Questions & Answers

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define metabolism of carbohydrates with example
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the process of keep equipment free from bacteria
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what are granulocytes
Shawnitta Reply
e.coli
Sukhdeep
granulocytes are type of WBCs which contains granules in the cytoplasm
Owili
suitable example for prokaryotes
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it's caused by a virulent bacteria called Salmonella Typhi
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control of microorganisms
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the process of killing
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the process of killing microorganisms
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genital herpes caused by a virus called herpe simplex virus
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facultative anaerobic bavteria gives uniform turdibity in nutrient broth why?
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@ MAHI because they can grow all over the media from surface to the bottom as they can utilize oxygen or conduct fermentation in its absence.
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2.@MAHI Autoclave uses steam under pressure. The steam cannot penetrate through oil and wax. Thus, dry heat sterilization is preferred than autoclave .
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because it's a general purpose agar only use for growing bacteria
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Antigen is a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.
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Practice MCQ 5

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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