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Prokaryotes

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prokaryotes
Class of organisms, including the eubacteria and archaea, that lack a true membrane-limited nucleus and other organelles. See also eukaryotes.


Prokaryotes, Eukaryotes, & Viruses Tutorial
Prokaryotes
Characteristics of prokaryotic cells.
As mentioned in the previous page, prokaryotes include the kingdoms of Monera (simple bacteria) and Archaea.

Prokaryotes are much smaller than eukaryotes. It's no surprise that Robert Hooke saw eukaryotic cells nearly a decade before Anton von Leeuwenhoek developed lenses strong enough to see a prokaryote. Prokaryotes average about 10% the length of eukaryotic cells.

prokaryotes
noun, plural form of prokaryote
Group of organisms that is primarily characterized by the lack of distinct, membrane-bound nucleus, or any other double membrane-bound organelles (e.g mitochondria, golgi apparatus, endoplasmic reticulum, etc.) withiin their cytoplasm.

PROKARYOTES - MISSING A NUCLEUS
If you're looking to learn about cells with a nucleus, this is the wrong place. Prokaryotes do not have an organized nucleus. Their DNA is kind of floating around the cell. It's clumped up, but not inside of a nucleus.

Prokaryotes are small.
Most prokaryotes are unicellular.
Some species may aggregate transiently or form true colonies, showing division of labor between specialized cell types.

Prokaryotes are "simple," single celled organisms, so they have "simple" systems
Genes are grouped together based on similar functions into functional units called operons
MANY GENES UNDER ONE CONTROL!!!
There is one single on/off switch for the genes ...

prokaryotes
an organism that is either a bacterium or a blue-green alga, its main characteristic being prokaryotic cells lacking a membrane-bound nucleus and no mitosis or meiosis.
Covered in BIOL1020 Lab 3 Cells ...

prokaryotes cells that do not contain a nucleus or internal organelles; include bacteria, cyanobacteria, and archaebacteria.
prophase the first phase of mitosis; involves chromosomal condensation, nuclear membrane breakdown, and the migration of centrioles to opposite poles.

Prokaryotes - Organisms whose cells lack internal organization into organelles and whose genetic material is not contained within a membrane-bound nucleus.

In prokaryotes
By studying prokaryotes, Francois Jacob and Jacques Monod discovered some of the most valuable concepts in gene regulation.

The prokaryotes (pronounced /proʊˈkærioʊtiːz/; singular prokaryote /proʊˈkæriət/) are a group of organisms that lack a cell nucleus (= karyon), or any other membrane-bound organelles. Most are unicellular, but some prokaryotes are multicellular organisms.

In prokaryotes
Reverse transcriptases are also found in bacterial Retron msr RNAs, distinct sequences which code for reverse transcriptase, and are used in the synthesis of msDNA. In order to initiate synthesis of DNA, a primer is needed.

Prokaryotes are much simpler in their organization than are eukaryotes. There are a great many more organelles in eukaryotes, also more chromosomes. The usual method of prokaryote cell division is termed binary fission.

Prokaryotes have small ribosomes (70S) compared to eukaryotes which have large ribosomes (80S).
In prokaryotes there are either no or very few organelles bounded by a single membrane in comparison to eukaryotes which have many of them including the Golgi apparatus and the endoplasmic reticulum.

Prokaryotes have some common characteristics. Compared to eukaryotic cells, they are small. Prokaryotic cells are usually between 1 and 10 microns, while eukaryotic cells are minimally 10 microns and usually larger.

Prokaryotes
- Organisms whose genetic material is not enclosed by a nucleus. The most common examples are bacteria.
Promoter ...

Prokaryotes the simplest organisms found on our earth constituting of a single small cell with no membrane-bounded nucleus
Prokaryotic cells that have no internal membranes or cytoskeleton.
Prolactin a hormone secreted by anterior pituitary gland.

In prokaryotes, the promoter consists of two short sequences at -10 and -35 position upstream of the gene, that is, prior to the gene in the direction of transcription. The sequence at -10 is called the Pribnow box and usually consists of the six nucleotides TATAAT.

In prokaryotes ribosomes are found free in cytoplasm. In eukaryotic cells they can also be found free in cytoplasm and mainly adhered to the external membrane of the karyotheca and of the rough endoplasmic reticulum.

In prokaryotes and plants, the plasma membrane is an inner layer of protection since a rigid cell wall forms the outside boundary for their cells. The cell wall has pores that allow materials to enter and leave the cell, but they are not very selective about what passes through.

In prokaryotes, horizontally acquired genes tend to be operational, typically encoding enzymes, rather than informational, that is, genes involved in transcription and translation [31].

Some prokaryotes are essential to the nitrogen cycle because of their role in nitrogen fixation, the conversion of nitrogen gas to ammonium ions. These ions can then be used to build amino acids. In aquatic environments cyanobacteria are the most significant nitrogen fixers.

In most prokaryotes, the chromosome is a circular DNA molecule. The origin (OriC) is where the replication bubble initiates and it is associated with the plasma membrane.

Proteins in prokaryotes responsible for termination of translation and release of the newly synthesized polypeptide when a nonsense codon appears in the A site of the ribosome. Replaced by eRF in eukaryotes.

Viruses and prokaryotes use a great deal more of their DNA than eukaryotes. Almost half the DNA in eukaryotic cells are repeated nucleotide sequences. This may be the result of millions of years of 'mistakes'.
Protein-coding sequences are interrupted by non-coding regions.

Biology of the Prokaryotes:
Biology of the Prokaryotes
eCampus.com
Biology with Infotrac:
Biology with Infotrac ...

However, there are photoautotrophs among the Prokaryotes, specifically photoautotrophic bacteria and cyanophytes. The latter are sometimes called (for good reasons) blue-green algae.

eukaryotes: Organisms whose cells have their genetic material packed in a membrane- surrounded, structurally discrete nucleus and with well- developed cell organelles. Eukaryotes include all organisms except archaebacteria and eubacteria (cg. prokaryotes). IUPAC Biotech ...

ocytes A group of prokaryotes currently classified among the Archaebacteria but possibly a sister group of eukaryotes.
eosinophil White blood cells characterized by the presence of cytoplasmic granules that become stained by an acid dye.

A DNA-binding protein in prokaryotes that blocks gene transcription by binding to the operator. Restriction endonuclease (enzyme). A class of endonucleases that cleaves DNA after recognizing a specific sequence, such as BamH1 (GGATCC), EcoRI (GAATTC), and HindIII (AAGCTT). Type I.

In prokaryotes, chromosomal DNA is circular, and the entire genome is carried on one chromosome. Eukaryotic genomes consist of a number of chromosomes whose DNA is associated with different kinds of proteins. (ORNL)
Chromosome painting ...

In prokaryotes, the relevant GTPases are: initiation factor IF2, which delivers the initiator tRNA to the P (peptide) site of the 30S ribosomal subunit; elongation factor EF-Tu, which delivers the aminoacyl-tRNA to the 70S ribosome (composed of 50S and 30S subunits); elongation factor EF-G, ...

This concludes what I'm going to discuss about prokaryotes. Several conclusions seem to emerge from these studies. First, given exponential growth and large population sizes, lots of mutations seem to occur in bacterial populations.

The cytoplasmic membrane of prokaryotes is fundamentally similar to that of a eukaryotic cell. The variety of proteins in the cytoplasmic membrane in prokaryotes is greater because of the significantly greater number of functions performed by it.

DNA usually occurs as linear chromosomes in eukaryotes, and circular chromosomes in prokaryotes. A chromosome is an organized structure consisting of DNA and histones.

Differences Between Eukaryotes and Prokaryotes
Bacteria (and archaea which are seldomly mentioned) are prokaryotes. The term prokaryotes is derived from pro (before) and karya (nucleus): before-nucleus = pro-karya = prokaryote.

In prokaryotes the transfer is a one-way process. The union of two bacterial cells, during which chromosomal material is transferred from the donor to the recipient cell. Conjugation in Protozoa is a two-way process, genetic material is passed between each conjugant.
Related Terms:
Prokaryote ...

When we divide the organisms that live on this planet, we make a distinction between those that have a nucleus, that are called eukaryotes, and those that don't have a nuclei, which we call prokaryotes.

There are the ribosomes found in prokaryotes like bacteria and their large subunits is just little bit smaller than the large subunit of eukaryotic cells like myself. We have a nucleus and our large subunit is larger than the large subunit of prokaryotes.

Hair-like structure attached to a cell, used for locomotion in many protists and prokaryotes.

Although prokaryotes share some common features because of the lack of membrane bound organelles (e.g., coupled transcription and translation are possible in prokaryotes but not in eukaryotes), overall the Archae are more similar to the Eukarya than they are to Bacteria.

The type of cell division by which prokaryotes reproduce; each dividing daughter cell receives a copy of the single parental chromosome.
binomial
[L. bi, twice, two + Gk. nomos, usage, law]
The two-part Latinized name of a species, consisting of genus and specific epithet.

bacteria (sing bacterium) /back-TEER-ee-ə; sing: -əm/ n. (1) broadly: prokaryotes; (2) strictly: one of the two major types of prokaryotes, the other type being archaeans (more information ) - bacterial. AGENTS OF COMMON BACTERIAL INFECTIONS ...

Linkage The proximity of two or more markers (e.g., genes, RFLP markers) on a chromosome; the closer together the markers are, the lower the probability that they will be separated during DNA repair or replication processes (binary fission in prokaryotes, mitosis or meiosis in eukaryotes), ...

Bacteria are prokaryotes. Compare eukaryote. See chromosomes.
Related Terms:
Nucleus
The term introduced by Brown (1833) for the more or less spherical structure which occures in cells and stains deeply with basic dyes. The cellular organelle in eukaryotes that contains the genetic material.

The pre-tRNA of prokaryotes and eukaryotes has extra nucleotides at the 5' and 3' extremities and in some eukaryotic pre-tRNAs introns are also present. Maturation of tRNA precursors is a multistep enzymatic process consisting of nucleolytic size reducing reactions and of nucleotide modifications.

The self-replicating genetic structure of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes. In prokaryotes, chromosomal DNA is circular, and the entire genome is carried on one chromosome.

Kingdom Monera the Kindgom to which prokaryotes such as bacteria and blue-green algae belong
(moner mono = one single) ...

Escherichia coli: A gram-negative bacterium whose genome has been sequenced in its entirety. It is model organisms for the study of the prokaryotes. Link to the E.coli genome project website.
EST (expressed sequence tag): A partial sequence of a cDNA molecule. See also STS.

Eukaryote: Organism whose cells have (1) chromosomes with nucleosomal structure and are separated from the cytoplasm by a two-membrane nuclear envelope, and (2) compartmentalization of functions in distinct cytoplasmic organelles. Contrast prokaryotes (bacteria and cyanobacteria).

See also: See also: Prokaryote, Cells, Cell, Protein, DNA

Biology  Prokaryote  Prokaryotic

 
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