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Structure of microbes

Bactericidal vs bacteriostatic - difference, value and different antimicrobials with these properties.
Doctor presenting two pills
© BSAC

Bacterial Structure

[labelled image] Capsule – Outside the cell wall, most bacteria have a sugar-based layer called a glycocalyx ranging from a diffuse, loosely bound, slimy coat, to a thick capsule. Capsules can provide protection against the host’s immune system, among other functions.

Ribosomes – Responsible for protein translation, prokaryotic versions are smaller, lighter, and structurally different from eukaryotic ribosomes.

Cell wall – Most bacteria have a thick, rigid cell wall that maintains the integrity of the cell and determines its shape. Destabilizing the cell wall leads to death.

Plasma membrane – Allows selective passage of substances in and out of the cell. Many of the enzymes associated with the metabolism of nutrients and production of energy are associated with the plasma membrane in bacteria.

Nucleoid – The genetic material of the bacterium (DNA). Usually anchored to the cell wall and circular.

Flagellum – Thin, whip-like structure used for locomotion.

Inclusion Body – Often act as food reserves.

Fimbriae – Also known as pili, these short, hair-like structures are used to anchor bacteria to a surfaces.

Fungus

[Labelled image] Ribosome – Same function as prokaryotes but different in size and structure. Similar to human ribosomes.

Mitochondrion – Creates high energy molecules for use in metabolism

Endoplasmic reticulum – Involved in protein synthesis and transport

Nucleus – A membrane-bound structure that contains the cell’s genetic material

Nucleolus – A region in the nucleus where ribosomes are assembled

Cell Wall – Provides strength and structure to the cell; contain chitin, a tough substance similar in composition to sea shells and insect exoskeletons

Cell membrane – The membrane that encases the cell and lies beneath the cell wall – signficantly different from human membranes

Golgi apparatus – An organelle involved in targeting of newly synthesized substances and proteins

Storage vacuole – Membrane-covered spaces within cells that serve to store nutrients and waste products

Centrioles – A cellular structure that plays a role in organizing the cell’s skeletal system

Protozoal

[labelled image]

Virus [labelled images]

© BSAC
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Introduction to Practical Microbiology

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