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4.2 Prokaryotic Cells
The components of the cell theory are listed.
There are cells that have a nucleus.
The size and shape of the archaeans were thought to be related to the bacteria.
The archaeans are different from either thebacteria or the eukaryotes.
These comparisons show that the archaeans are related to the eukaryotes.
The Eubacteria and Archaea are prokaryotic cells, while all eukaryotic cells are assigned to domain Eukarya.
One of the most abundant and diverse life forms on Earth is the prokaryotes, and they are present in great numbers in the air, water, and soil.
Their metabolism is much better than that of eukaryotes, even though they are less complicated.
The evolutionary history of prokaryotes goes back to the first cells on Earth.
bacteria cause serious diseases, such as tetanus, throat infections, and gonorrhea Many species ofbacteria contribute to the environment by decomposing dead organisms.
We usebacteria to manufacture all sorts of products, from industrial chemicals to foodstuffs and drugs.
Today, we know how to place human genes in certain culturedbacteria so that they can produce humaninsulin, a necessary hormone for the treatment of diabetes.
The average size of prokaryotes is 1.1- 1.5 um wide and 2.0- 6.0 um long.
A spherical-shaped bacterium is called a coccus.
Both of these can occur as pairs or chains.
Some long rods are twisted into spirals and can be either rigid or flexible.
The figure shows the structure of a bacterium.
For the sake of discussion, we divide the organization ofbacteria into the cell envelope, the cytoplasm, and the external structures.
Prokaryotic cells do not have a nucleus.
There is a region called a nucleoid.
Section 5.1 will give us a better idea of the structure of the plasma membrane.
In order to maintain the cell's normal composition, it is necessary to regulate the flow of materials into and out of the cytoplasm.
Mesosomes increase the internal surface area for the attachment of enzymes.
Even if the cytoplasm takes up a lot of water, the cell wall keeps the shape of the cell.
The cell wall of a bacterium contains a complex molecule called peptidoglycan.
Several classes of antiobiotics target the peptidoglycan component of the cell well.
There is a layer of polysaccharides outside of the cell wall.
A slime layer is not well organized and easy to remove.
bacteria resist a host's immune system by using the glycocalyx.
bacteria attach almost any surface
The cytoplasm is a semifluid solution made up of water, inorganic and organic Molecules.
The many types of chemical reactions involved in metabolism are speeded up by a variety of enzymes.
eukaryotic cells have multiple chromosomes while prokaryotes have a single coiled chromosomes.
Extrachromosomal pieces of circular DNA are called plasmids.
The use of plismids in laboratories to transport DNA into a bacterium is common.
All life on Earth is made up of the same four genes: A, G, C, and T.
The production of new medicines and many of the commercial products we use every day can be done with the help of the Biotechnology industry.
Prokaryotic ribosomes have the same genes in two different parts.
There is a lot of diversity in the prokaryotes.
The metabolism of prokaryotes is the same as that of animals, but the metabolism of the cyanobacteria is different.
These organisms live in water, in ditches, on buildings, and on the bark of trees.
Their cytoplasm contains a lot of cells.
Some blue-greenbacteria add a shade of blue to their cells by adding the green color of chlorophyll.
Some of the earliest photosynthesizers on Earth were the ancestral cyanobacteria.
The composition of the early Earth's atmosphere was changed by the addition of oxygen.
The flagella, fimbriae, and conjugate pili are external structures of a prokaryote.
The appendages called flagella propel the motile prokaryotes in water.
One of the great wonders of nature is the prokaryotic flagellum, which consists of a hook and a filament.
The cell wall is anchored by a series of rings.
The flagellum of the prokaryotes has a whiplike motion, but it rotates at a slower rate.
Sometimes flagella occur only at the two ends of a cell, and sometimes they are dispersed randomly over the surface.
The number and location of flagella can be used to distinguish different types of prokaryotes.
Fimbriae are small, bristlelike fibers that grow from the cell surface.
Fimbriae are involved in attaching prokaryotes to a surface.
Prokaryotes can exchange their genes by way of the pili.
They can take up the genetic material from the outside or from the inside.
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