Prokaryotes Vs Eukaryotes

Compare and contrast prokaryotic and eukaryotic cells

Life began on Earth around 3.5 billion years ago as the earliest living organisms to exist were the prokaryotes, which thrived in anaerobic environments and survived where there were high levels of radiation, very low pH levels, and extreme temperatures (1). Bacteria and archaea are the groups of organisms which make up the prokaryotes, which is the largest group of living organisms inhabiting the biosphere today (1). Approximately 1 billion years after the prokaryotes were established, the eukaryotic cell developed on Earth (2). Prokaryote means “before the nucleus” and eukaryote means “true nucleus”, and thus it is ultimately the presence of the nucleus within a cell that divides all cells into the two groups of prokaryotes and eukaryotes (2).

Firstly, the majority of prokaryotic cells and eukaryotic cells are single-celled, although prokaryotes have a diameter measuring up to 5 millimetres, which is a similar size to the nucleus of a eukaryotic cell and eukaryotic cells are usually 10-100 millimetres in diameter (1) (2). Eukaryotic cells can also be found in colonies and multicellular species (1).

As shown in figure 1,

The main difference in the DNA organisation between eukaryotes and prokaryotes is that prokaryotes tend to have a circular double stranded DNA loop found in the nucleoid as well as having DNA plasmids, whereas the chromosomes of eukaryotes are linear (1). Nonetheless, chromosomes are fundamental structures that are common to both prokaryotes and eukaryotes as they contain the genetic material of the cell (1). The extra DNA plasmids that prokaryotes have contain genes coding for special properties such as antibiotic resistance (4). Eukaryotes and prokaryotes have very different genomes and the simplest group within the eukaryotes are the fungi, which have the smallest genome of all the eukaryotes