| Transcription is a process by which the genetic information present in the DNA is copied to an intermediate molecule (RNA). The sequence in the RNA is complementary to that of the gene which is transcribed and thus the RNA retains the same information as the gene itself. Transcription is a universal process in the living word and it occurs both in prokaryotes and eukaryotes. Even though the overall process of transcription is similar in both prokaryotes and eukaryotes, there do exists some fundamental differences between these groups. Show
This post summarizes the overall similarities and differences between the Prokaryotic and Eukaryotic transcription in a detailed but easy way. Similarities between prokaryotic and eukaryotic transcription 1. In both groups DNA acts as the template for RNA synthesis 4. Transcription is facilitated by the enzyme RNA polymerase in both groups 5. In both groups, one strand of the DNA duplex acts as the template Difference between prokaryotic and eukaryotic transcription
Sl. No.Prokaryotic TranscriptionEukaryotic Transcription1Transcription and translation are continuous process and occurs simultaneously in the cytoplasmThey are two separate processes, transcription occurs in the nucleus whereas translation occurs in the cytoplasm2Transcription initiation machinery is simple since DNA is not associated with any histone proteinsTranscription initiation machinery is very complex since the genetic material is associated with proteins3Only one type of RNA polymerase enzyme, which synthesize all types of RNA in the cell (mRNA, rRNA and tRNA)Three types of RNA polymerase in the cell. RNA Polymerase I for rRNA synthesis RNA Polymerase II for mRNA synthesis. RNA polymerase III for tRNA and 5S rRNA synthesis4RNA polymerase with 5 subunits, Two α subunits, One β subunit, One β’ subunit, One ω subunit. Functional RNA polymerase is 2α1β1β’ωRNA polymerase I with 14 subunits, RNA polymerase II with 10 -12 subunits, RNA polymerase II with 12 subunits5σ factor present, which is essential for transcription initiationσ absent and it is not required for transcription initiation. Initiation of transcription is facilitated by initiation factors6RNA polymerase can recognize and bind to the promoter region with the help of σ factorRNA polymerase cannot recognize the promoter region directly unless the promoter is pre-occupied by transcription initiation factors.7Promoter region always located upstream to the start sitePromoter region usually located upstream to the start site, but rarely as in the case of RNA polymerase III, promoter is located downstream to start site8Promoter region contain pribnow box at -10 positions. TATA box and CAT box are absent in the promoter region of prokaryotesPromoter region contains; TATA box located 35 to 25 upstream; CAT box located ~ 70 nucleotide upstream; GC box located ~ 110 nucleotide upstream. Pribnow box absent in eukaryotes9Termination of transcription is done either by rho dependent mechanisms or rho independent mechanismsA termination mechanism of transcription is not completely known. It may be direct by the poly A signal or by the presence of termination sequence in the DNA10Usually there is no post transcriptional modification of the primary transcriptPrimary transcript undergo post transcriptional modifications (RNA editing)11RNA capping absent, mRNA is devoid of 5’ guanosine capRNA capping present, capping occurs at the 5’ position of mRNA12Poly A tailing of mRNA is absentMature mRNA with a poly A tail at the 3’ position. Poly A tail is added enzymatically without the complementary strand13Introns absent in the mRNAIntrons present in the primary transcript14Splicing of mRNA absent since introns are absentSplicing present, introns in the primary transcript are removed and exons are rejoined by a variety of splicing mechanisms15Genes usually polycistronic and hence single transcript may contain sequence for many polypeptidesGenes are monocistronic thus single transcript code for only one polypeptide16SD sequence (Shine-Dalgarno sequence) present about 8 nucleotide upstream of start codon in the mRNA, SD sequence act as the ribosome binding siteSD sequence is absent in mRNA of prokaryotes Eukaryotes are organisms whose cells possess a nucleus enclosed within a cell membrane, making up one of the three domains of life, Eukaryota. They include multicellular organisms such as plants, animals, and fungi. Bacteria and Archaea, the other two domains of life, are prokaryotic cells. They do not possess membrane-bound cellular compartments, such as nuclei.  Similarities between eukaryotic and prokaryotic cellsCell MembraneBoth eukaryotic and prokaryotic cells bear a lipid bilayer, which is an arrangement of phospholipids and proteins that acts as a selective barrier between the internal and external environment of the cell. Genetic MaterialEukaryotic and prokaryotic cells both use deoxyribonucleic acid (DNA) as the basis for their genetic information. This genetic material is needed to regulate and inform cell function through the creation of RNA by transcription, followed by the generation of proteins through translation. RibosomesRibosomes facilitate RNA translation and the creation of protein, which is essential to the functioning of both eukaryotic and prokaryotic cells. CytoplasmThe cytoplasm is the medium in which the biochemical reactions of the cell take place, of which the primary component is cytosol. In eukaryotic cells, the cytoplasm comprises everything between the plasma membrane and the nuclear envelope, including the organelles; the material within the nucleus is termed the nucleoplasm. In prokaryotes the cytoplasm encompasses everything within the plasma membrane, including the cytoskeleton and genetic material. Differences between eukaryotic and prokaryotic cellsCell sizeEukaryotic cells are ordinarily larger (10 – 100um) than prokaryotic cells (1 – 10um). Cell arrangementGenetics & Genomics eBookCompilation of the top interviews, articles, and news in the last year. Eukaryotes are often multicellular whereas prokaryotes are unicellular. There are however some exceptions –unicellular eukaryotes include amoebas, paramecium, yeast. True membrane-bound nucleusEukaryotic cells have a true nucleus bound by a double membrane. It contains the DNA-related functions of the large cell in a smaller enclosure to ensure close proximity of materials and increased efficiency for cellular communication and functions. In contrast, the smaller prokaryotic cells have no nucleus. The materials are already fairly close to each other and there is only a "nucleoid" which is the central open region of the cell where the DNA is located. DNA structureEukaryotic DNA is linear and complexed with packaging proteins called "histones," before organization into a number of chromosomes Prokaryotic DNA is circular and is neither associated with histones nor organized into chromosomes. A prokaryotic cell is simpler and requires far fewer genes to function than the eukaryotic cell. Therefore, it contains only one circular DNA molecule and various smaller DNA circlets (plasmids). Membrane-bound organellesEukaryotic cells contain many membrane-enclosed, large, complex organelles in the cytoplasm whereas prokaryotic cells do not contain these membrane-bound organelles. This is a key difference because it allows a high level of intracellular division of labor and contributes to the greater complexity characteristic of eukaryotic cells. Due to the larger size of the eukaryotic cells, confining certain cellular process to a smaller area also increases the efficiency of functions by improving communication and movement within the cell. Only eukaryotes possess a membrane-bound nucleus and membrane-bound organelles such as the mitochondria, golgi apparatus, lysosomes, peroxisomes and ER. Ribosome sizeBoth eukaryotic and prokaryotic cells contain many ribosomes; however the ribosomes of the eukaryotic cells are larger than prokaryotic ribosomes i.e. 80S compared to 70S. Eukaryotic ribosomes also show more complexity than prokaryotic – they are constructed of five kinds of ribosomal RNA and about eighty kinds of proteins. In contrast, prokaryotic ribosomes are composed of only three kinds of rRNA and about fifty kinds of protein. CytoskeletonThis is a multicomponent system in eukaryotes composed of microtubules, actin filaments and intermediate filaments. It is required for maintaining cell shape, providing internal organization and mechanical support. It is also paramount in movement and cell division. Sexual reproductionMost eukaryotes undergo sexual reproduction whilst prokaryotes reproduce asexually. Sexual reproduction in eukaryotes results in offspring with genetic material which is a mixture of the parents’ genome and during this process, genetic variation is generated via sexual recombination. On the other hand, a prokaryote will reproduce clones of itself via binary fission and relies more on horizontal genetic transfer for variation. Cell divisionThis occurs by mitosis for eukaryotic cells and binary fission for prokaryotic cells. Eukaryotic cells undergo mitosis then cytokinesis. This involves numerous stages - the nuclear membrane disintegrates then the chromosomes are sorted and separated to ensure that each daughter cell receives two sets (a diploid number) of chromosomes. Following this, the cytoplasm divides to form two genetically identical daughter cells i.e. cytokinesis. In contrast, prokaryotes undergo a simpler process of binary fission. This is faster than mitosis and involves DNA (nucleoid) replication, chromosomal segregation, and ultimately cell separation into two daughter cells genetically identical to the parent cell. Unlike mitosis, this process does not involve the nuclear envelope and centromere and spindle formation. What are similarities and differences between eukaryote and prokaryote transcription translation?Answer: Eukaryotic Transcription takes place inside of the Nucleus, while Prokaryotic Transcription takes place in the Cytoplasm. In Eukaryotic Transcription, proteins known as Transcriptional factors are needed, while In Prokaryotic Transcription, no such proteins are needed.
What is one similarity between prokaryotes and eukaryotes in translation?Similarities Between Prokaryotic and Eukaryotic Translation Initiation. Both processes use an mRNA template. tRNA brings up the correct amino acid in both processes. Both ribosomal subunits take part in translation initiation.
What is one way that transcription between bacteria and eukaryotes is similar?Answer and Explanation: Transcription between bacteria and eukaryotes is similar in that both types of organism use a single strand of the DNA duplex to serve as the template of RNA synthesis by the enzyme RNA polymerase.
What is a similarity between eukaryotic and prokaryotic?Eukaryotic and prokaryotic cells both use deoxyribonucleic acid (DNA) as the basis for their genetic information. This genetic material is needed to regulate and inform cell function through the creation of RNA by transcription, followed by the generation of proteins through translation.
|
