Prokaryote - Revision history

DavidB4-bot: /* top */Spelling, Grammar, and flow, typos fixed: ill defined → ill-defined

2018-05-17T06:09:08Z

top: Spelling, Grammar, and flow, typos fixed: ill defined → ill-defined

DavidB4-bot: /* top */Spelling/Grammar Check, typos fixed: a ill → an ill

2016-08-10T18:57:03Z

top: Spelling/Grammar Check, typos fixed: a ill → an ill

DavidB4-bot: clean up & uniformity

2016-07-13T17:54:25Z

clean up & uniformity

CSGuy: I really don't know why I keep coming back.

2008-09-30T02:52:26Z

I really don't know why I keep coming back.

JohnDavis: expand

2008-07-23T22:52:03Z

expand

JohnDavis: correct, multiple classes exist eg in archaea

2008-07-23T22:48:08Z

correct, multiple classes exist eg in archaea

Vossy: wiki, links

2007-05-06T08:16:42Z

wiki, links

GodlessLiberal: redirected prokaryotes here

2007-05-04T23:38:42Z

redirected prokaryotes here

New page

The structure of a prokaryote is very much simpler than that of a eukaryote. There are no endomembranes, endosymbionts, nucleus or cytoskeleton. The DNA is carried on the genophore, a circular chromosome, in a ill defined area of the cytosol called the nucleoid. The chromosome is attached to the cell membrane during cell division (fission), frequently at a point called the mesosome.

#πρό-καρυον (pro-karyon) - before kernel.
#No nucleus - free circular genophore.
#'Simple' rotating motor-type flagellum.
#Cell division by fission, genophore attached to plasmalemma by mesosome.
#Few membrane-bound organelles, no double-membrane bound organelles.
#They are 'small' because diffusion limits the rate of transport across the cell - 1 μm.
[[Image:Bacterial_cell.png|center||Prokaryotes are characterised by the lack of a nucleus and membranes bound organelles.]]
The cytosol contains oil droplets, food reserves and the 70S ribosomes, and is surrounded by a plasmalemma. In Gram negative bacteria, a further outer membrane surrounds the plasmalemma, with a thin cell wall and periplasmic space trapped between them. In Gram positive bacteria, there is no outer membrane, and the cell wall is thicker. The cell wall is composed of peptidoglycan and various organic acids in Eubacteria. Bacteria have flagella, but they are simple proteinaceous strands attached to a rotary motor, completely dissimilar to the complex eukaryotic undulipodium. Membranes may be present in the cell, as in the thylakoids of the Cyanobacteria. The cytosol may also contain various episomes (small circular chromosomes), some called plasmids, and others called (bacterio)phages, which are bacterial viruses.

Prokaryotes are extraordinarily diverse:

Proteobacteria - Gram-negative, two cell membranes, hugely diverse, ''[[Escherichia coli]]''.

Firmicutes and Actinobacteria - Gram-positive, thick peptidoglycan cell wall.

Spirochaetes - helical bacteria.

Prokaryotic DNA lacks histones (packaging proteins), although other packaging proteins are present, and molecules have easier access to DNA compared with eukaryotes. They generally have efficient genomes, with little sequence other than coding sequence or regulatory sequence. Transcription is by just one class of RNA polymerase. Transcription leads to translation with no intermediate processing, which allows several genes to be encoded in a single transcriptional unit (a polycistron). They have small (70S) ribosomes.

[[Category:Molecular Biology]]
[[Category:microbiology]]

← Older revision		Revision as of 06:09, May 17, 2018
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−	The structure of a '''prokaryote''' is very much simpler than that of a [[eukaryote]]. There are no endomembranes, endosymbionts, nucleus or cytoskeleton. The [[DNA]] is carried on the genophore, a circular chromosome, in an ill defined area of the cytosol called the nucleoid. The chromosome is attached to the cell membrane during cell division (fission), frequently at a point called the mesosome.	+	The structure of a '''prokaryote''' is very much simpler than that of a [[eukaryote]]. There are no endomembranes, endosymbionts, nucleus or cytoskeleton. The [[DNA]] is carried on the genophore, a circular chromosome, in an ill-defined area of the cytosol called the nucleoid. The chromosome is attached to the cell membrane during cell division (fission), frequently at a point called the mesosome.

	#πρό-καρυον (pro-karyon) - before kernel.		#πρό-καρυον (pro-karyon) - before kernel.

← Older revision		Revision as of 18:57, August 10, 2016
Line 1:		Line 1:
−	The structure of a '''prokaryote''' is very much simpler than that of a [[eukaryote]]. There are no endomembranes, endosymbionts, nucleus or cytoskeleton. The [[DNA]] is carried on the genophore, a circular chromosome, in a ill defined area of the cytosol called the nucleoid. The chromosome is attached to the cell membrane during cell division (fission), frequently at a point called the mesosome.	+	The structure of a '''prokaryote''' is very much simpler than that of a [[eukaryote]]. There are no endomembranes, endosymbionts, nucleus or cytoskeleton. The [[DNA]] is carried on the genophore, a circular chromosome, in an ill defined area of the cytosol called the nucleoid. The chromosome is attached to the cell membrane during cell division (fission), frequently at a point called the mesosome.

	#πρό-καρυον (pro-karyon) - before kernel.		#πρό-καρυον (pro-karyon) - before kernel.

@@ Line 7: / Line 7: @@
 #Few membrane-bound organelles, no double-membrane bound organelles.
 #They are 'small' because diffusion limits the rate of transport across the cell - 1 μm.
-[[Image:Bacterial_cell.png|center||Prokaryotes are characterised by the lack of a nucleus and membranes bound organelles.]]
+[[Image:Bacterial_cell.png|center|Prokaryotes are characterised by the lack of a nucleus and membranes bound organelles.]]
 The cytosol contains oil droplets, food reserves and the 70S ribosomes, and is surrounded by a plasmalemma. In Gram negative bacteria, a further outer membrane surrounds the plasmalemma, with a thin cell wall and periplasmic space trapped between them. In Gram positive bacteria, there is no outer membrane, and the cell wall is thicker. The cell wall is composed of peptidoglycan and various organic acids in Eubacteria. Bacteria have flagella, but they are simple proteinaceous strands attached to a rotary motor, completely dissimilar to the complex eukaryotic undulipodium. Membranes may be present in the cell, as in the thylakoids of the Cyanobacteria. In gram-positive bacteria the mambrane may form [[mesosome]]s, which are invaginations in the cell membrane that may be involved in DNA replication and oxidative phosphorylation. The cytosol may also contain various episomes (small circular chromosomes), some called plasmids, and others called (bacterio)phages, which are bacterial viruses.
@@ Line 23: / Line 23: @@
 {{GFDL|copyright=(c) 2002-2008 Steve Cook}}
 [[Category:Molecular Biology]]
-[[Category:microbiology]]
+[[Category:Microbiology]]

@@ Line 1: / Line 1: @@
 The structure of a '''prokaryote''' is very much simpler than that of a [[eukaryote]]. There are no endomembranes, endosymbionts, nucleus or cytoskeleton. The [[DNA]] is carried on the genophore, a circular chromosome, in a ill defined area of the cytosol called the nucleoid. The chromosome is attached to the cell membrane during cell division (fission), frequently at a point called the mesosome.
 #πρό-καρυον (pro-karyon) - before kernel.
@@ Line 8: / Line 8: @@
 #They are 'small' because diffusion limits the rate of transport across the cell - 1 μm.
 [[Image:Bacterial_cell.png|center||Prokaryotes are characterised by the lack of a nucleus and membranes bound organelles.]]
-The cytosol contains oil droplets, food reserves and the 70S ribosomes, and is surrounded by a plasmalemma. In Gram negative bacteria, a further outer membrane surrounds the plasmalemma, with a thin cell wall and periplasmic space trapped between them. In Gram positive bacteria, there is no outer membrane, and the cell wall is thicker. The cell wall is composed of peptidoglycan and various organic acids in Eubacteria. Bacteria have flagella, but they are simple proteinaceous strands attached to a rotary motor, completely dissimilar to the complex eukaryotic undulipodium. Membranes may be present in the cell, as in the thylakoids of the Cyanobacteria. The cytosol may also contain various episomes (small circular chromosomes), some called plasmids, and others called (bacterio)phages, which are bacterial viruses.
+The cytosol contains oil droplets, food reserves and the 70S ribosomes, and is surrounded by a plasmalemma. In Gram negative bacteria, a further outer membrane surrounds the plasmalemma, with a thin cell wall and periplasmic space trapped between them. In Gram positive bacteria, there is no outer membrane, and the cell wall is thicker. The cell wall is composed of peptidoglycan and various organic acids in Eubacteria. Bacteria have flagella, but they are simple proteinaceous strands attached to a rotary motor, completely dissimilar to the complex eukaryotic undulipodium. Membranes may be present in the cell, as in the thylakoids of the Cyanobacteria. In gram-positive bacteria the mambrane may form [[mesosome]]s, which are invaginations in the cell membrane that may be involved in DNA replication and oxidative phosphorylation. The cytosol may also contain various episomes (small circular chromosomes), some called plasmids, and others called (bacterio)phages, which are bacterial viruses.
 Prokaryotes are extraordinarily diverse:
@@ Line 18: / Line 18: @@
 ''Spirochaetes'' - helical bacteria.
-Prokaryotic DNA lacks histones (packaging [[protein]]s), although other packaging proteins are present, and molecules have easier access to DNA compared with eukaryotes. They generally have efficient genomes, with little sequence other than coding sequence or regulatory sequence. Transcription leads to translation with no intermediate processing, which allows several genes to be encoded in a single transcriptional unit (a polycistron). They have small (70S) ribosomes.
+Prokaryotic DNA lacks histones (packaging [[protein]]s), although other packaging proteins are present, and molecules have easier access to DNA compared with eukaryotes. They generally have efficient genomes, with little sequence other than coding sequence or regulatory sequence. Transcription leads to translation with no intermediate processing, which allows several genes to be encoded in a single transcriptional unit (a polycistron). No bacterial [[intron]]s exist. They have small (70S) ribosomes.
 [[Category:Molecular Biology]]
 [[Category:microbiology]]

@@ Line 18: / Line 18: @@
 ''Spirochaetes'' - helical bacteria.
-Prokaryotic DNA lacks histones (packaging [[protein]]s), although other packaging proteins are present, and molecules have easier access to DNA compared with eukaryotes. They generally have efficient genomes, with little sequence other than coding sequence or regulatory sequence. Transcription is by just one class of RNA polymerase. Transcription leads to translation with no intermediate processing, which allows several genes to be encoded in a single transcriptional unit (a polycistron). They have small (70S) ribosomes.
+Prokaryotic DNA lacks histones (packaging [[protein]]s), although other packaging proteins are present, and molecules have easier access to DNA compared with eukaryotes. They generally have efficient genomes, with little sequence other than coding sequence or regulatory sequence. Transcription leads to translation with no intermediate processing, which allows several genes to be encoded in a single transcriptional unit (a polycistron). They have small (70S) ribosomes.
 [[Category:Molecular Biology]]
 [[Category:microbiology]]