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EXPLAIN THE STRUCTURE OF TYPICAL BACTERIAL CELL.

Structure of bacteria

  • Have cell wall surrounding the cell membrane

  • Absence of a well-defined nucleus

  • May have plasmids − small, circular, extra-chromosomal DNAs present in addition to the genomic DNAs; this confers characteristics like antibiotic resistance to bacteria, and help in transformation.

  • Cell Envelope − Three-Layered Structure

    • Glycocalyx (Outermost): May be present in the form of loose sheath called slime layer in some bacteria, or as a thick and tough capsule in others

    • Cell wall (middle): Determines the shape of a cell and provides a strong structural support

    • Plasma Membrane (innermost): Semi-permeable and structurally similar to that of eukaryotic cells.

  • Mesosome 

    • Formed by the extension of the plasma membrane into the cell

    • These extensions are made up of vesicles, tubules and lamellae.

    • Functions: Cell wall formation; DNA replication and distribution; respiration and secretion processes; increase surface area of plasma membrane and enzymatic content

  • Bacteria may be − Motile or Non-Motile

    • Motile: Have flagella

    • Non-motile: Lack flagella

  • Flagella has three parts: Filament, Hook, Basal body

  • Pili (tubular structures made of proteins) and fimbriae (bristle-like fibres) are also present along with flagella, but their function is attachment (to the substratum or the host cell).

  • Depending upon the cell envelope, bacteria are of two types:

    • Gram positive − take up gram stain

    • Gram negative − do not take up gram stain

Ribosome

  • Associated with plasma membrane

  • Made up of two subunits: 50S and 30 S = 70S

  • Site of protein synthesis

  • Polysome: When several ribosomes attach to a single mRNA

  • Help in the translation of mRNA into proteins

Inclusion Bodies

  • Reserve material in bacterial cell is stored in the form of inclusion bodies.

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OH CAN SOMEONE NOW ANSWER THIS...?PLEASE........:-I

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Procaryotic structural components consist of macromolecules such as DNA, RNA, proteins, polysaccharides, phospholipids, or some combination thereof. The macromolecules are made up of primary subunits such as nucleotides, amino acids and sugars (Table 1). It is the sequence in which the subunits are put together in the macromolecule, called the primary structure, that determines many of the properties that the macromolecule will have. Thus, the genetic code is determined by specific nuleotide base sequences in chromosomal DNA; the amino acid sequence in a protein determines the properties and function of the protein; and sequence of sugars in bacterial lipopolysaccharides determines unique cell wall properties for pathogens. 

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 structure 

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