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{{short description|Round shape of certain bacteria or archaea}}
{{for|the genus of scale insects|Coccus (insect)}}
{{for|the genus of scale insects|Coccus (insect)}}
{{redirect|Cocci|the fungal disease|Coccidioidomycosis}}
{{redirect|Cocci|the fungal disease|Coccidioidomycosis}}
{{distinguish|Cocchi}}
{{distinguish|Cocchi}}
{{Merge to|Bacterial cellular morphologies|discuss=Talk:Bacterial cellular morphologies#Proposed merge of Coccus into Bacterial cellular morphologies|date=December 2023}}
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{{Use dmy dates|date=April 2022}}
[[File:Staphylococcus aureus Gram.jpg|thumb|300px|''Staphylococcus'' bacteria]]
[[File:Staphylococcus aureus Gram.jpg|thumb|300px|''Staphylococcus'' bacteria]]
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A '''coccus''' (plural '''cocci''') is any [[bacterium]] or [[archaeon]] that has a spherical, ovoid, or generally round shape.<ref name="arrangement">{{cite book|last1=Pommerville|first1=J.C.|title=Fundamentals of Microbiology|date=2013|publisher=Jones & Bartlett|location=Sudbury, MA|isbn=9781449647964|page=106|edition= 10th}}</ref><ref name=":0">{{Cite book|title=Sherris medical microbiology|last=Ryan|first=Kenneth James|isbn=9781259859809|edition=7th|location=New York|publisher=McGraw-Hill Education|oclc=983825627}}</ref> Bacteria are categorized based on their shapes into three classes: cocci (spherical-shaped), [[bacillus (shape)|bacillus]] (rod-shaped) and spirochetes ([[spiral bacteria|spiral-shaped]]) cells.<ref name=":0" /> Coccus refers to the shape of the bacteria, and can contain multiple genera, such as staphylococci or streptococci. Cocci can grow in pairs, chains, or clusters, depending on their orientation and attachment during cell division. Contrast to many bacilli-shaped bacteria, most cocci bacteria do not have flagella and are non-motile.<ref name=":1">{{Cite book|title=Review of medical microbiology & immunology: a guide to clinical infectious diseases|last1=Levinson|first1=Warren|last2=Joyce|first2=Elizabeth A.|last3=Nussbaum|first3=Jesse|last4=Schwartz|first4=Brian S.|last5=Chin-Hong|first5=Peter|isbn=9781259644498|edition=15th|location=New York|publisher=McGraw-Hill Education|oclc=1032261353}}</ref>


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A '''coccus''' ({{plural form}}: '''cocci''') is any [[bacterium]] or [[archaeon]] that has a spherical, ovoid, or generally round shape.<ref name="arrangement">{{cite book|last1=Pommerville|first1=J.C.|title=Fundamentals of Microbiology|date=2013|publisher=Jones & Bartlett|location=Sudbury, MA|isbn=9781449647964|page=106|edition= 10th}}</ref><ref name=":0">{{Cite book|title=Sherris medical microbiology|last=Ryan|first=Kenneth James|date=4 January 2018|isbn=9781259859809|edition=7th|location=New York|publisher=McGraw-Hill Education|oclc=983825627}}</ref> Bacteria are categorized based on their shapes into three classes: cocci (spherical-shaped), [[bacillus (shape)|bacillus]] (rod-shaped) and spiral ([[spiral bacteria|of which there are two types: spirillum and spirochete]]).<ref name=":0" /> Coccus refers to the shape of the bacteria, and can contain multiple genera, such as staphylococci or streptococci. Cocci can grow in pairs, chains, or clusters, depending on their orientation and attachment during cell division. In contrast to many bacilli-shaped bacteria, most cocci bacteria do not have flagella and are non-motile.<ref name=":1">{{Cite book|title=Review of medical microbiology & immunology: a guide to clinical infectious diseases|last1=Levinson|first1=Warren|last2=Joyce|first2=Elizabeth A.|last3=Nussbaum|first3=Jesse|last4=Schwartz|first4=Brian S.|last5=Chin-Hong|first5=Peter|date=10 May 2018|isbn=9781259644498|edition=15th|location=New York|publisher=McGraw-Hill Education|oclc=1032261353}}</ref>
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Cocci is an English [[loanword]] of a [[New Latin|modern or neo-Latin]] noun, which in turn stems from the [[Ancient Greek language|Greek]] masculine noun ''cóccos (κόκκος)'' meaning "berry".<ref>{{LSJ|ko/kkos|κόκκος|ref}}</ref>


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Cocci is an English [[loanword]] of a [[Neo-Latin|modern or Neo-Latin]] noun, which in turn stems from the [[Ancient Greek|Greek]] masculine noun {{lang|grc|κόκκος}} ({{lang|grc-Latn|cóccos}}) meaning 'berry'.<ref>{{LSJ|ko/kkos|κόκκος|ref}}</ref>
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'''Cocci Structure'''


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==Structure==
Structure for cocci may vary between gram positive and gram negative bacterial wall types.  


The cell wall structure for cocci may vary between gram positive (thick peptidoglycan layers) and gram negative (thin peptidoglycan layers). While living in their host organism, cocci can be pathogenic (e.g., streptococcus), commensal, or symbiotic.<ref name=":0" />
The [[cell wall]] structure for cocci may vary between gram-positive (thick peptidoglycan layers) and gram-negative (thin peptidoglycan layers). While living in their host organism, cocci can be pathogenic (e.g., streptococcus), commensal, or symbiotic.<ref name=":0" />


'''Gram-Positive Cocci'''
==Gram-positive Cocci==


The Gram-Positive Cocci are a large group of loosely bacteria with similar morphology. All are the spherical or nearly so, but they vary considerably in size. Members of some genera are identifiable by the way cells are attached to one another: in pockets, in chains, or grapes like clusters. These arrangements reflect patterns of cell division and fact that cell stick together. ''Sarcina'' cells, for example, are arranged in cubical pockets because cell division alternates regularly among the three perpendicular planes. ''Streptococcus'' spp. resemble a string of beads because division always occurs in the same plane. Some of these strings, for example, ''S. pneumoniae,'' are only two cells long. They are called ''diplococci.'' Species of ''Staphylococcus'' have no regular plane of division. They form grape-like structures.<ref name="Ingraham">{{Cite book|title=Introduction to Microbiology|first1=Catherine A.|last1=Ingraham|first2=John L.|last2=Ingraham|publisher=|year=2000|isbn=|location=|pages=}}</ref>
The [[Gram-positive bacteria|gram-positive]] cocci are a large group of bacteria with similar morphology. All are spherical or nearly so, but they vary considerably in size. Members of some genera are identifiable by the way cells are attached to one another: in pockets, in chains, or grape-like clusters. These arrangements reflect patterns of cell division and that cells stick together. ''Sarcina'' cells, for example, are arranged in cubical pockets because cell division alternates regularly among the three perpendicular planes. ''Streptococcus'' spp. resemble a string of beads because division always occurs in the same plane. Some of these strings, for example, ''S. pneumoniae,'' are only two cells long. They are called ''diplococci.'' Species of ''Staphylococcus'' have no regular plane of division. They form grape-like structures.<ref name="Ingraham">{{Cite book|title=Introduction to Microbiology|url=https://archive.org/details/introductiontomi0000ingr|url-access=registration|first1=Catherine A.|last1=Ingraham|first2=John L.|last2=Ingraham|year=2000}}</ref>


The various Gram-positive cocci differ physiologically and by habitat. ''Micrococcus'' spp. are obligate aerobes that inhabit human skin. ''Staphylococcus'' spp. also inhabit human skin, but they are facultative anaerobes. They ferment sugars, producing lactic acid as an end product. Many of these species produce carotenoid pigments, which color their colonies yellow or orange. ''Staphylococcus aureus'' is a major human pathogen. It can infect almost Any tissue in the body, frequently the skin. It often causes nasocomial(hospital-acquired) infections.<ref name="Ingraham"/>
The various gram-positive cocci differ physiologically and by habitat. ''Micrococcus'' spp. are obligate aerobes that inhabit human skin. ''Staphylococcus'' spp. also inhabit human skin, but they are facultative anaerobes. They ferment sugars, producing lactic acid as an end product. Many of these species produce carotenoid pigments, which color their colonies yellow or orange. ''[[Staphylococcus aureus]]'' is a major human pathogen. It can infect almost any tissue in the body, frequently the skin. It often causes nosocomial (hospital-acquired) infections.<ref name="Ingraham"/>


== Arrangements ==
== Arrangements ==
Cocci may occur as single cells or remain attached following cell division. Those that remain attached can be classified based on cellular arrangement:<ref name="arrangement"/>
Cocci may occur as single cells or remain attached following cell division. Those that remain attached can be classified based on cellular arrangement:<ref name="arrangement"/>
*'''[[Diplococci]]''' are pairs of cocci (e.g. ''[[Streptococcus pneumoniae]]'' and ''[[Neisseria gonorrhoeae]]'')
* '''[[Diplococci]]''' are pairs of cocci (e.g. ''[[Streptococcus pneumoniae]]'' and ''[[Neisseria gonorrhoeae]]'')
*'''[[Streptococci]]''' are chains of cocci (e.g. ''[[Streptococcus pyogenes]]'').
* '''[[Streptococci]]''' are chains of cocci (e.g. ''[[Streptococcus pyogenes]]'').
*'''[[Staphylococci]]''' are irregular (grape-like) clusters of cocci (e.g. ''[[Staphylococcus aureus]]'').
* '''[[Staphylococci]]''' are irregular (grape-like) clusters of cocci (e.g. ''[[Staphylococcus aureus]]'').
*'''[[wikt:tetrad|Tetrads]]''' are clusters of four cocci arranged within the same plane (e.g. ''[[Micrococcus]] sp.'').
* '''[[wikt:tetrad|Tetrads]]''' are clusters of four cocci arranged within the same plane (e.g. ''[[Micrococcus]] sp.'').
*'''[[Sarcina (genus)|''Sarcina'']]''' is a genus of bacteria that are found in cuboidal arrangements of eight cocci (e.g. ''[[Sarcina (genus)|Sarcina ventriculi]]'').
* '''[[Sarcina (genus)|''Sarcina'']]''' is a genus of bacteria that are found in cuboidal arrangements of eight cocci (e.g. ''[[Sarcina (genus)|Sarcina ventriculi]]'').


== References ==
== References ==
{{reflist}}
{{Reflist}}

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{{Use dmy dates|date=June 2011}}
{{Bacteria}}
{{Bacteria}}
{{Authority control}}


[[Category:Bacteria]]
[[Category:Bacteria]]

Revision as of 15:18, 10 December 2023

For the genus of scale insects, see Coccus (insect).
"Cocci" redirects here. For the fungal disease, see Coccidioidomycosis.
Not to be confused with Cocchi.

Staphylococcus bacteria

A coccus (pl.: cocci) is any bacterium or archaeon that has a spherical, ovoid, or generally round shape.[1][2] Bacteria are categorized based on their shapes into three classes: cocci (spherical-shaped), bacillus (rod-shaped) and spiral (of which there are two types: spirillum and spirochete).[2] Coccus refers to the shape of the bacteria, and can contain multiple genera, such as staphylococci or streptococci. Cocci can grow in pairs, chains, or clusters, depending on their orientation and attachment during cell division. In contrast to many bacilli-shaped bacteria, most cocci bacteria do not have flagella and are non-motile.[3]

Cocci is an English loanword of a modern or Neo-Latin noun, which in turn stems from the Greek masculine noun κόκκος (cóccos) meaning 'berry'.[4]

Structure

The cell wall structure for cocci may vary between gram-positive (thick peptidoglycan layers) and gram-negative (thin peptidoglycan layers). While living in their host organism, cocci can be pathogenic (e.g., streptococcus), commensal, or symbiotic.[2]

Gram-positive Cocci

The gram-positive cocci are a large group of bacteria with similar morphology. All are spherical or nearly so, but they vary considerably in size. Members of some genera are identifiable by the way cells are attached to one another: in pockets, in chains, or grape-like clusters. These arrangements reflect patterns of cell division and that cells stick together. Sarcina cells, for example, are arranged in cubical pockets because cell division alternates regularly among the three perpendicular planes. Streptococcus spp. resemble a string of beads because division always occurs in the same plane. Some of these strings, for example, S. pneumoniae, are only two cells long. They are called diplococci. Species of Staphylococcus have no regular plane of division. They form grape-like structures.[5]

The various gram-positive cocci differ physiologically and by habitat. Micrococcus spp. are obligate aerobes that inhabit human skin. Staphylococcus spp. also inhabit human skin, but they are facultative anaerobes. They ferment sugars, producing lactic acid as an end product. Many of these species produce carotenoid pigments, which color their colonies yellow or orange. Staphylococcus aureus is a major human pathogen. It can infect almost any tissue in the body, frequently the skin. It often causes nosocomial (hospital-acquired) infections.[5]

Arrangements

Cocci may occur as single cells or remain attached following cell division. Those that remain attached can be classified based on cellular arrangement:[1]

References

  1. ^ a b Pommerville, J.C. (2013). Fundamentals of Microbiology (10th ed.). Sudbury, MA: Jones & Bartlett. p. 106. ISBN 9781449647964.
  2. ^ a b c Ryan, Kenneth James (4 January 2018). Sherris medical microbiology (7th ed.). New York: McGraw-Hill Education. ISBN 9781259859809. OCLC 983825627.
  3. ^ Levinson, Warren; Joyce, Elizabeth A.; Nussbaum, Jesse; Schwartz, Brian S.; Chin-Hong, Peter (10 May 2018). Review of medical microbiology & immunology: a guide to clinical infectious diseases (15th ed.). New York: McGraw-Hill Education. ISBN 9781259644498. OCLC 1032261353.
  4. ^ κόκκος. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project
  5. ^ a b Ingraham, Catherine A.; Ingraham, John L. (2000). Introduction to Microbiology.
source: https://en.wikipedia.org/w/index.php?title=Coccus&diff=1189228850&oldid=927915712

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