2. Eukaryotes and Prokaryotes

Eukaryote vs. Prokaryote

Prokaryotes are organisms characterized by lacking a nucleus and other membrane-bound cytoplasmic structures. They are considerably smaller than eukaryotes. They also have a greater surface area to volume ratio and therefore have greater metabolic rates. Examples of prokaryotes are eubacteria and archaea.

Eukaryotes have a nucleus that contains nuclear DNA. The nucleus has a lipid bilayer membrane that is perforated with nuclear pores. The DNAs inside the nucleus are complexed with histone proteins forming chromatin. In cell division, the chromatin condenses into a chromosome. The chromosomes are linear strands of DNA as opposed to the chromosomes of prokaryotes that are mostly circular.

Both eukaryotes and prokaryotes have genetic information stored in genes. Their main source of metabolic energy is ATP. Both of them also have ribosomes that assist during protein synthesis. However, the ribosomes of eukaryotes are 80S. In prokaryotes, the ribosomes are 70S. Both prokaryotic and eukaryotic ribosomes are made up of two ribosomal subunits. The prokaryotic ribosome (70S) is made up of 50S (large subunit) and 30S (small subunit). The eukaryotic ribosome (80S) consists of 60S (large subunit) and 40S (small subunit). [N.B. the S units do not add up since they represent measures of sedimentation rate, not mass.]

Leave a Reply

Your email address will not be published. Required fields are marked *