BiologyGram-Negative Bacteria Cell Wall – Diseases, Characteristics, Classification, Infections and Causes

Gram-Negative Bacteria Cell Wall – Diseases, Characteristics, Classification, Infections and Causes

Gram-Negative Diseases

There are a number of Gram-negative diseases, which are caused by bacteria that have a negative charge on their cell walls. This charge repels the positively-charged staining dye used in the Gram stain, which is why these bacteria appear as a lighter color than Gram-positive bacteria.

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    Some of the most common Gram-negative diseases include:

    • Tuberculosis, which is a bacterial infection that can affect the lungs.
    • Cholera, a water-borne bacterial infection that can cause severe diarrhea.
    • Gonorrhea, a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae.
    • Urinary tract infections, which are infections of the urinary system, often caused by the bacteria Escherichia coli.
    • Septicemia, a potentially life-threatening condition caused by bacteria invading the bloodstream.

    Gram-Negative Bacteria Cell Wall

    Gram-negative bacteria are surrounded by a cell wall that is composed of a peptidoglycan layer and an outer membrane. The peptidoglycan layer is composed of a glycan (sugar) backbone and peptides (amino acids). The peptides are cross-linked by peptide bridges to form a mesh-like structure.

    The outer membrane is a lipid bilayer that surrounds the peptidoglycan layer and is composed of phospholipids and lipopolysaccharides (LPSs). LPSs are composed of a lipid core, a glycan chain, and a protein anchor.

    The LPS lipid core is composed of a core lipid and a core oligosaccharide. The core oligosaccharide is composed of a lipid, a glycan, and a protein. The glycan chain is composed of a repeating unit of two sugars, N-acetylglucosamine and N-acetylmuramic acid.

    Gram-Negative Bacteria Infections and Causes

    Gram-negative bacteria infections are caused by bacteria that have a thin cell wall and a negative charge on their outer surface. This negative charge repels positively charged dyes, such as the Gram stain. As a result, gram-negative bacteria appear pink or red under a microscope, while gram-positive bacteria appear blue or purple.

    Gram-negative bacteria can cause a variety of infections, including respiratory infections, urinary tract infections, and sepsis. They are also responsible for a significant proportion of hospital-acquired infections.

    One of the main ways that gram-negative bacteria spread is through contact with contaminated surfaces. They can also be spread through contact with infected animals or people. In addition, some gram-negative bacteria can be spread through the air.

    Some of the most common gram-negative bacteria include Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa.

    Classification of Gram-Negative Bacteria

    There are a variety of ways to classify Gram-negative bacteria, but one of the most common methods is by their biochemical properties. This system classifies bacteria into four main groups:

    1. Enterobacteria: This group includes common pathogens such as Salmonella and E. coli. They are typically rod-shaped and are facultative anaerobes, meaning they can survive in the presence or absence of oxygen.

    2. Gram-negative rods: This group includes a variety of bacteria that are not classified in any of the other groups. They are typically rod-shaped and are either facultative anaerobes or obligate anaerobes.

    3. Aerobic gram-negative bacilli: This group includes bacteria that require oxygen to survive and typically have a spiral or comma-shaped morphology.

    4. Anaerobic gram-negative bacilli: This group includes bacteria that do not require oxygen to survive and typically have a rod-shaped morphology.

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