Essay writing differences and similarities between prokaryotes

Eukaryotic cells are therefore are found in all other living organisms, the name implying that there is a proper nucleus present.

As there is no nucleus present in prokaryotic cells the DNA helix is a single coiled chromosome that is unsupported and so can float freely around the cell, however in a eukaryotic cell the DNA helix is made up of linear chromosomes supported by the histone protein.

In Eukaryotic cells there is also a distinct nuclear membrane Prokaryotic cells are smaller than Eukaryotic cells, according to “Pharmaceutical Microbiology” the majority of bacteria fall within the general dimensions of 0.75 to 4mm compared to the size of common eukaryotic cells which can be up to 40 times larger than Prokaryotic cells and measure between 50 and 150mm.

Prokaryotic cells and Eukaryotic cells both can contain a cell wall however in prokaryotic cells the cell wall is peptidoglycan (a mixture of sugar and protein) if the organism is a eubacteria, or pseudomurein if the organism is a archae bacteria whereas in eukarotic cells a cell wall is only present if the organism is a plant or a fungi and the cell wall is constructed of cellulose in plants or chitin if the organism is a fungi.

Prokaryotic cells and Eukaryotic cells can both contain cytoplasm.

However, the size of the ribosome differs- in a prokaryote the ribosome is around 70 Svedberg’s, while in a Eukaryote it’s larger at around 80 Svedberg’s.

Both cells have similar metabolisms and are amazingly diverse in their forms- for example there are dangerous prokaryotes such as Streptococcus gonorrhoea, which causes gonorrhoea, and useful prokaryotes such as Nitrosomonas used in the nitrogen cycle.

Diverse Eukaryotes range from unicellular yeast for making bread, to multicellular humans.

However, both eukaryotes and prokaryotes have great differences.

Most notably the lack of a nucleus in prokaryotes and membrane bound organelles.

The DNA of prokaryotes floats freely around the cell; the DNA of eukaryotes is held within its nucleus.

The organelles of eukaryotes allow them to exhibit much higher levels of intracellular division of labour than is possible in prokaryotic cells.

Another physical difference is the size of both cells.

A prokaryote is only 0.5-5 μm, whilst Eukaryotes are on average 10 times bigger at up to 40μm.

Mitochondria are absent from Prokaryotes, yet found in Eukaryotes, as are chloroplasts (though chloroplasts are not found in animal cells).

Both have similarities and differences in their functions and structures.

Both Prokaryote and Eukaryote cells consist of Cell wall, (however this is not present in animal cells) – this is made of Peptidoglycan (though the plant cell is made of cellulose microfibrils embedded in a layer of calcium pectate and hemicelluloses).

The cell wall provides support for a plant cell, and controls what goes in and out, allowing the cell to build a hydrostatic skeleton, giving the cell shape and rigidity.

The Cells also contain a cell membrane made of phospholipids and proteins, designed to control what goes in and out of the cell.

DNA is also found in both cells, which carries the genetic information for the cell, allowing for replication. The ribosome is made of r RNA and they synthesise protein, as they are the site where m RNA meets t RNA so that amino acids are bonded together.

One difference as far as existence is concerned, is that prokaryotes are believed to be the first form of life around 3.5 billion years ago.

Eukaryotes are much younger, and believed to have existed around 1.5 billion years ago when the cells developed a nucleus- multicellular organisms are younger still at 0.5 billion years old.

One theory as to why cells developed organelles such as mitochondria and chloroplasts are suggested in the theory of endosymbiosis.

The theory suggests that mitochondria and chloroplasts were free living bacteria (prokaryotes) and ended up becoming part of an early cell.

This is theory is supported by the fossil record showing that oxygen began to accumulate between the fossil records of prokaryotes and the later record of eukaryotes.

The cell is the basic functioning unit of organisms in which chemical reactions take place.

These reactions involve an energy release needed to support life and build structures.

The cell consists of membrane bound organelles, which are responsible for the division of labour.

There are two main classes of cells- Prokaryotes which are cells without a nucleus, where the DNA is spread around the cytoplasm of the cell, an example of a prokaryote is a bacterium (See Figure 1).

The other class is the Eukaryotes which are the cells of plants and animals, and example is a palisade cell (See Figure 2).

The similarities and differences between eukaryotic and prokaryotic cells Prokaryotic and Eukaryotic cells are the two main types of cell found in living organisms.

They share many similarities and also many differences.

These differences are key to how they function and which jobs they are suitable to perform.

Prokaryotic cells are cells that contain a very primitive nucleus as pro- means before and karyon is a Greek word, meaning nucleus.

Prokaryotic cells are found in organisms such as bacteria, most commonly eubacteria and archae bacteria.

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