Define And Give Examples Of Bacterial Morphology. What Are The Relative Sizes Of Different Cells?

Bacteria
Size, Shape and Organisation

Definition

Bacteria are single-celled and are classified nether the domain Prokaryota. As such, they lack membrane-bound organelles like those plant in eukaryotes.

Although they are all microscopic organisms that can be found in various environments in nature, bacteria widely vary in size, shape, and arrangement.

* The majority of bacteria species are microscopic, however, studies have identified large bacteria that tin be seen with the naked center.

Bacterial Size

In full general, bacteria are between 0.2 and 2.0 um - the average size of most bacteria. Enquiry studies accept shown their size to play an of import function in survival over time.

Due to their pocket-sized size, bacteria are able to exploit and thrive in various microenvironments. These include such environments equally the vertical gradients in intertidal marine sediments in which various types of leaner have been found. Because various microorganisms are absent in such environments, bacteria successfully exploit resources available and thrive in such environments.

The small size of leaner is likewise beneficial for parasitism and oligotrophy. Bacteria can continue relying on a range of hosts (large and modest) for their nutrition. In addition, they can as well live and survive in environments that contain a low concentration of nutrients; for instance, a group of leaner known equally oligotrophic bacteria.

Leaner have a high surface expanse to volume ratio that allows them to take upward as many nutrients as possible for survival. In the process, they are able to continue growing and reproducing at a steady rate.

In bacteriology, the micron (micrometer) is the principal unit of measurement: I micrometer (um) is ane-thousandth of a millimeter.

* Given that the limit of resolution for a human middle (naked heart) is betwixt 100 and 200 um (most the diameter of a homo pilus) then the bulk of leaner cannot exist seen with the naked heart.

The following are different sizes of bacteria:

Boilerplate Size

According to many microbiology books, the average size of most bacteria is between 0.2 and 2.0 micrometer (diameter). Nonetheless, there are some that agree this to range betwixt 1 and x micrometers. This, however, just considers the diameter of the organisms and not the length.

For example, whereas East. coli leaner range between i.i and 1.5 um in diameters, B. anthracis range betwixt one.0 and 1.2um while B. subtilis range betwixt 0.25 and ane.0um in diameter. They besides vary in length when compared to each other.

Smallest Bacteria

At that place has been some debate most their classification simply some of the smallest leaner are microorganisms known equally nanobacterium.

They are characterized past their ho-hum growth under aerobic weather likewise as existence Gram-negative in nature. Although they have been shown to range between 0.2 and 0.5um (200 to 500 nanometers) there have been studies where some were found to filter through 0.1um filters.

Some examples of these bacteria include Mycoplasmas (virtually 0.25um), Haemophilus influenzae which ranges betwixt 0.ii and 0.3um and Mycoplasma gallicepticum which range betwixt 200 and 300 nanometers in diameter.

* Although such bacteria as Mycoplasma lack a cell wall, they tin exist independently. They are institute in such hosts equally human beings, plants and a variety of insects.

Large Leaner

Some bacteria are big enough to see with the naked eye. For instance, whereas Schaudinnum bütschlii that measure between 4 and 5um in bore are considered to exist large leaner, Thiomargarita namibiensis may grow to exist as large equally 0.75mm in diameter. This makes them some of the largest bacteria ever discovered. As such, they tin can be seen with the naked eye - when they accomplish such sizes.

* The Thiomargarita namibiensis is a Gram-negative bacterium that is coccoid in shape. Information technology was discovered in body of water sediments in Namibia (Southwest of Africa).

Shape and Arrangement

Morphologically, leaner are microscopic single-celled organisms that are small in size and lack membrane bound organelles. A majority of these organisms also have a cell wall and sheathing that protects the inner contents of the cell where the nucleoid, ribosome, plasmid, and cytoplasm are constitute.

While a majority of leaner share these characteristics, they vary in shape which allows dissimilar types of bacteria to be classified based on their general shape.

The following are the major categories of leaner based on their shapes:

Cocci

Cocci leaner announced spherical or oval in shape. For the near role, the shape is determined by the prison cell wall of the organism and therefore varies from one type of cocci bacteria to another. Cocci bacteria may exist every bit single cells or remain attached to each other.

Attached Cocci leaner include:

Diplococci bacteria - Diplococci leaner are the type of cocci bacteria that occur every bit a pair (two joined cells).

Some examples of Diplococci bacteria include:

Streptococcus pneumoniae
Moraxella catarrhalis
Enterococcus spp
Neisseria gonorrhea

While some of these cells may be truly round shaped, others may appear elongated (ovoid) or edible bean-shaped/kidney shaped. For instance, some Neisseria cells may announced round while others are edible bean-shaped when viewed under the microscope.

Tetrad bacteria - Tetrad leaner are arranged in groups of four cells. Post-obit sectionalization, the cells remain fastened and grow in this attachment.

Common examples of Tetrad leaner include:

Pediococcus
Tetragenococcus

Sarcinae sarcina/Leaner - Sarcina bacteria occur in groups of 8 cells. Dissimilar tetrads that carve up into two planes, Sarcinae is produced through the perpendicular plane division.

Some of the characteristics associated with these bacteria include being strict anaerobes, Gram-positive bacteria and that measure between ane.5 and 3.0 um.

Examples of Sarcinae bacteria include:

Sarcina aurantiaca
Sarcina lutea
Sarcina ventriculi

Streptococci Bacteria - Streptococci bacteria are a type of bacteria that accommodate in a chain grade (resembling chains). A majority of these bacterial cells are also ovoid in shape and may course paired chains.

Every bit members of the family Streptococcaceae, this group of bacteria is characterized past being non-motile, Gram-positive organisms.

Examples of Streptococcus leaner include:

Streptococcus pyogenes
Streptococcus pneumoniae
Southward. mutans

Staphylococci Bacteria - Staphylococci Bacteria are a type of bacteria that form grape-like clusters. This blazon of arrangement is the upshot of division that occurs in two planes. 2 of the principal characteristics of these organisms are that they are immobile, Gram-positive bacteria.

Examples of Staphylococci leaner include:

Staphylococcus epidermidis
Staphylococcus haemolyticus
Staphylococcus aureus
Staphylococcus capitis

Bacillus Leaner (Rod-Shaped)

Bacillus bacteria accept the following traits:

Are all rod-shaped
Form endospores
Facultative anaerobes

Like cocci leaner, bacillus bacteria are likewise arranged differently. While some exist as single, unattached cells (east.1000. Salmonella enterica subsp, Bacillus cereus, and Salmonella choleraesuis), others are attached.

The following are the unlike types of bacillus arrangements:

Diplobacilli bacteria - Like Diplococci bacteria, Diplobacilli occur in pairs. Following jail cell division, the two cells do not split up and continue existing as a pair.

Examples of Diplobacilli bacteria include:

Coxiella burnetii
Klebsiella rhinoscleromatis
Moraxella bovis

Streptobacilli - Streptobacilli bacteria occur as elongated chains. As such, they are the result of division on a unmarried plane.

Common examples of Streptobacilli include:

Streptobacillus moniliformis
Streptobacillus Levaditi
Streptobacillus felis
Streptobacillus hongkongensis

Coccibacilli bacteria - Compared to other bacilli, Coccibacilli leaner are shorter in length and thus appear stumpy.

Examples of Coccibacilli include:

Chlamydia trachomatis
Haemophilus influenzae

* Palisades are another type of bacilli bacteria. Prison cell sectionalization of these bacteria results in a type of system that resembles a picket argue. One of the best examples of palisades is the Corynebacterium diphtheria that is responsible for diphtheria.

Unlike cocci and bacilli leaner, some types of leaner appear curved when viewed under the microscope. However, they vary in shape making information technology possible to differentiate them from each other.

These include:

Vibrio bacteria - Generally, vibrio bacteria are comma-shaped and thus not fully twisted (curved rods).

Examples of Vibrio bacteria include:

Vibrio mytili
Vibrio anguillarum
Vibrio parahaemolyticus
Vibrio cholerae

Spirochete - Spirochetes are characterized by a helical shape. Spirochetes are also flexible and take been shown to produce mycelium. The movement involves the use of axial filaments, which is one of the distinguishing features betwixt the bacteria and other types of leaner.

* Axial filaments in spirochetes are located between the inner and outer membrane. They run forth the length of the bacteria and are responsible for the twisting motion of the organisms.

Examples of Spirochetes include:

Leptospira
Spirochaeta
Treponema

Spirilla leaner - Similar Spirochetes, Spirilla bacteria possess a helical shape. Yet, they are more rigid and have the typical flagella found in other types of bacteria.

Some examples of Spirilla bacteria include:

Aquaspirillum
Campylobacter jejuni
Spirillum winogradskyi
Oceanospirillum

Other Types of Bacteria based on the Shape

Some leaner possess various odd shapes that distinguish them from other types of bacteria.

These include:

Rectangular bacteria- They appear rectangular in shape e.thousand. Haloarcula marismortui
Star-shaped bacteria- Look like stars (star-shaped) e.g. Stella humosa
Haloarcula- Triangular in shape
Pleomorphic bacteria- Leaner with the power to change their shape and size in unlike environments, e.k. M. pneumonia
Stalked leaner- These include such leaner as C. crescentus that possess a stalk on 1 finish of the jail cell

More on Cells:

Eukaryotes - Jail cell Structure and Differences

Prokaryotes - Cell Structure and Differences

Protists - Discovering the Kingdon Protista in Microscopy

Paramecium - Classification, Construction, Part and Characteristics
Vorticella - Characteristics, Structure, reproduction and Habitat

Diatoms - Classification and Characteristics

Fungi - Mold Under the Microscope , Aspergillus type

Algae - Reproduction, Identification and Nomenclature

Protozoa - Anatomy, Nomenclature, Life Bicycle and Microscopy

Bacteria - Morphology, Types, Habitat, looking at anaerobes, Eubacteria

Archaea - Definition, Examples, Characteristics and Classification

Of interest: What are Viruses?, How do Bacteria cause Disease?, Virus Vs Bacteria, How do antibiotics kill bacteria?, List of Diseases caused by Leaner, Does Peroxide kill Bacteria

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References

Kevin D. Immature. (2006). The Selective Value of Bacterial Shape. American Guild for Microbiology.

Moshtaq Talip Al-mohanna. (2016). Morphology And Classification Of Bacteria. ResearchGate.

Siamak Yaghobee and Mojtaba Bayani. (2015). What are the nanobacteria?. ResearchGate.

James T. Staley. (1999). Size Limits of Very Small Microorganisms: Proceedings of a Workshop.

Links

https://www.pnas.org/content/95/fourteen/8274

https://world wide web.nature.com/articles/nrmicro1205

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