Cells are divided into two categories namely the Prokaryotes and Eukaryotes. These two have varying differences between them. Speaking in simple cell biology words, prokaryotes are primitive, simple organisms that lack membranous cell organelles. The opposite of this are eukaryotes, which are advanced and complex organisms having membrane bound cell organelles. Seemingly simple in structure and markedly different from eukaryote and protist organisms, prokaryotic cells are believed to have been amongst the first on the Earth and very well may out-survive all other organisms. Examples of prokaryotes are bacteria and archaea and eukaryotes include fungi, animal and plant cells. One of the main differentiating points between the two is the presence or absence of membrane enclosed nuclear body. In prokaryotes, it lacks outer membrane covering and nucleolus, whereas nucleolus is present and a double layered membrane surrounds the nuclear body in eukaryotes. Referred to as cell nucleus in eukaryotes, such an organelle is called nucleoid in prokaryotes. The nuclear body houses the chromosome in both prokaryotes and eukaryotes. Single in number and circular in shape, the chromosome in prokaryotes is made up of Deoxyribonucleic Acid (DNA) and proteins whilst in eukaryotes, it is usually more than two in number, and composed of DNA, histone and other proteins.
In terms of ribosomes prokaryotes consist of 70S type, and the two subunits are 50S and 30S. Ribosome in eukaryotes is of 80S type, and the two comprising subunits are 60S and a 40S. Since the cell size in prokaryotes is relatively smaller to that of the eukaryotes, the organelles like mitochondria, golgi bodies, endoplasmic reticulum and chloroplast are absent in the small-sized prokaryotic cells whilst Eukaryotic cells house all these membrane bound organelles inside the cell. Cell division in prokaryotes is simple, and occurs by binary fission method. Over here, the parent cell (haploid cell) divides into two equal daughter cells. Eukaryotes have diploid cell that divides first by mitosis, and further into two haploid ones by meiosis. The resulting haploid gametes fuse to give a diploid cell.
The Essay on Differences Between Prokaryote And Eukaryote Cells
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 ...
Prokaryotes are generally able to carry out their life processes of growth, energy generation and reproduction independently of other cells which is very different to the cells of eukaryotes which are unable to live alone in nature and can exist only as part of a multicellular organism. Most eukaryotic cells are uniquely suited to their own particular environmental niche and rarely grows out of it, but prokaryotes i.e. bacteria can grow in a multiplicity of environments ranging from hot sulphur springs (65°C) to deep freezers (–20°C) and also in nutritionally poor environment. A major difference in chemical composition between prokaryotic and eukaryotic cells is that eukaryotes have sterols in their membranes (e.g. cholesterol) whereas the plasma membrane of prokaryotic cells does not contain carbohydrates and generally lacks sterols. In prokaryotic cells the enzymes, topoisomerases, that control topological changes in DNA architecture are different from their eukaryotic counterparts (act on linear Chromosomes).
The cytoplasm of prokaryotes is densely packed with ribosomes that are not associated with a membranous structure ie endoplasmic reticulum whilst in eukaryotic cells the ribosomes can either be free lying or bound to the endoplasmic reticulum.
Prokaryotes maintain their DNA in a supercoiled state by the combined action of two enzymes that can alter the linking number of DNA without changing its primary structure. These enzymes are called DNA topoisomerases. One of the bacteria enzymes, DNA gyrase, utilizes the energy of ATP to induce supertwists in the bacterial chromosome and the other, DNA topoisomerase I, relaxes supercoiled DNA. It is the combined action of these two opposing enzymes that allows bacteria to maintain a delicate balance and proper super helical density of the chromosome required for replication, repair, recombination and gene function. In higher organisms, supercoiled DNA results from the wrapping and unwrapping of the DNA in a left-handed helical path around the major structural proteins of the chromosome, histones. The wrapping of DNA around histones requires the action of DNA topoisomerases to resolve the topological constraints imposed during wrapping. Translation may occur at the same time as transcription in prokaryotes, whilst they always occur separately in eukaryotes.
The Essay on Plasmid Fusion Pcr Dna Cells Lab
Josh Hyman Per. 5 Plasmid Fusion & PCR The AMGEN Lab that we have been doing for the past two weeks consisted of two parts; Plasmid Fusion and PCR. Each one is a complicated procedure of genetic engineering, with our own cheek cells and E. Coli supplied by AMGEN. I will start by explaining the Plasmid Fusion lab. The Plasmid Fusion lab consisted of four major parts; plasmid digestion, gel ...
The lack of a nuclear membrane in prokaryotes has the advantage of allowing the cell to translate RNA as it is transcribed from DNA. This means that even before the full RNA is produced, the protein coded by the RNA can start being made. Eukaryotes produce RNA inside the nucleus, so it must first be fully transcribed and undergo modification before it can be moved to the cytoplasm where translation occurs. In prokaryotes the Glycocalyx is present as a capsule or slime layer, whilst in eukaryotes it is present in some cells that lack a cell wall. In prokaryotes the flagella consist of two protein building blocks but when in eukaryotes it is complex, consisting of multiple microtubules .
