Essential Steps in Protein Synthesis: Comparing Eukaryotes and Prokaryotes
The process used to transfer the genetic information stored in the DNA into units of transportable complementary RNA replicas, is called Eukaryotic Transcription.
In prokaryotes transcription occurs in the cytoplasm of the cell as it lacks the membrane-bound nuclei and other organelles.
Difference Between Prokaryotic And Eukaryotic Translation
In the process of translation, the nucleotide triplets, also known as the codons, present on the mRNA will be translated into amino acid sequence.
Protein synthesis involves the process of Eukaryotic and Prokaryotic Translations.
The major difference between eukaryotic and prokaryotic translation that lies is that the eukaryotic translation and transcription is a process that is asynchronous whereas prokaryotic translation and transcription is a synchronized process. The Difference between Prokaryotic And Eukaryotic Translation are as follows -
Cell Size
Eukaryotic cells are larger (10 – 100um) than the prokaryotic cells (1 – 10um).
Cell Arrangement
The arrangement of the cells are also different. Eukaryotes are often multicellular whereas prokaryotes are unicellular.
True Membrane-Bound Nucleus
Eukaryotic cells double membrane surrounded by true nucleus. It performs the functions of the large cell in a smaller enclosure to ensure that there is close proximity to materials and increased efficiency for cellular communication and functions that are generally DNA-related.
DNA Structure
Eukaryotic DNA is linear and complex along with the packaging proteins that are known as the "histones," named before organization into a number of chromosomes. Prokaryotic DNA is circular. It is neither linked with histones nor organized into chromosomes.
For a clear understanding of the differences between Prokaryotic and Eukaryotic Translations, have a look at the table below -
Differences Between Prokaryotic and Eukaryotic Translations
Prokaryotic Cells
Prokaryotes are one of the most ancient groups of living organisms which derives the meaning as being ‘Before Nuclei’ on earth, with fossil records dating back to almost 3.5 billion years ago.
These prokaryotes were found in the earth’s ancient environment, some using up chemical energy and others using the sun’s energy. These extremophiles survived for millions of years, evolving and adapting. Scientists made a conclusion that these organisms gave rise to the eukaryotes.
Eukaryotic Cells
Eukaryotes are more complex and much larger than the prokaryotes. Almost all the major kingdoms are included in this except for kingdom monera. Structure wise, eukaryotes possess a cell wall, which supports and protects the plasma membrane. The cell is surrounded by the plasma membrane and it controls the entry and exit of certain substances.
Similarities Between Eukaryotic and Prokaryotic Cells
Along with some differences, there are also some similarities between the Eukaryotic and Prokaryotic Cells. The similarities are the following -
Cell Membrane
Both eukaryotic and prokaryotic cells consist of a lipid bilayer, which is an arrangement of phospholipids and proteins that is a selective barrier between the internal and external environment of the cell.
Genetic Material
Both the Eukaryotic and prokaryotic cells use deoxyribonucleic acid (DNA) as the basis for their genetic information. This genetic material is needed to regulate and perform the cell function through the creation of RNA by transcription, followed by the generation of proteins through translation.
Ribosomes
Ribosomes help in theRNA translation and also the creation of protein, which is essential to the smooth functioning of both eukaryotic and prokaryotic cells.
Cytoplasm
The cytoplasm is the place in which the biochemical reactions of the cell take place, of which the primary component is cytosol. In eukaryotic cells, the cytoplasm consists of everything between the plasma membrane and the nuclear envelope, including the organelles; the material within the nucleus is termed the nucleoplasm.
FAQs on Eukaryotic vs Prokaryotic Translation Explained
1. What is the fundamental process of translation in biology?
Translation is the crucial biological process where the genetic information encoded in a messenger RNA (mRNA) molecule is decoded to synthesise a specific protein. This process is carried out by ribosomes in the cell's cytoplasm, effectively converting the language of nucleotides into the language of amino acids, which are the building blocks of proteins.
2. What is the main difference between translation in prokaryotic and eukaryotic cells?
The primary difference lies in the location and timing. In prokaryotes, translation is coupled with transcription, meaning it begins while the mRNA is still being synthesised, as both processes occur in the cytoplasm. In eukaryotes, these processes are separated; transcription happens inside the nucleus, and the mature mRNA is then exported to the cytoplasm for translation.
3. How do ribosomes and mRNA molecules differ in prokaryotic vs. eukaryotic translation?
There are key differences in the machinery used for translation:
Ribosomes: Prokaryotes use smaller 70S ribosomes (composed of 30S and 50S subunits). Eukaryotes use larger 80S ribosomes (composed of 40S and 60S subunits).
mRNA: Prokaryotic mRNA is often polycistronic, meaning one mRNA can code for multiple proteins, and it contains a Shine-Dalgarno sequence for ribosome binding. Eukaryotic mRNA is typically monocistronic (one mRNA, one protein), and it is processed with a 5' cap and a poly-A tail to enhance stability and aid in ribosome recognition.
4. What are the three essential stages of the translation process?
The process of translation is universally divided into three key stages in both prokaryotes and eukaryotes:
Initiation: The assembly of the ribosome on the mRNA template.
Elongation: The sequential addition of amino acids to the growing polypeptide chain based on the mRNA codons.
Termination: The release of the completed polypeptide chain when a stop codon is reached.
5. Why is the initiating amino acid different in prokaryotic and eukaryotic translation?
The difference in the initiating amino acid reflects the distinct initiation mechanisms. Prokaryotes use N-formylmethionine (fMet) as their first amino acid. This modification helps in distinguishing the initiator methionine from internal ones. Eukaryotes, on the other hand, use a standard methionine (Met) as their initiator amino acid, recognised by a special initiator tRNA (tRNAi).
6. What is the functional importance of translation being coupled with transcription in prokaryotes?
The coupling of transcription and translation in prokaryotes allows for an incredibly rapid and efficient response to environmental stimuli. Because there is no nuclear membrane to cross, protein synthesis can begin on an mRNA molecule almost as soon as it starts being transcribed. This enables bacteria to quickly produce enzymes and other proteins needed for survival or to metabolise a newly available nutrient source.
7. How does a ribosome identify the correct starting point for translation on an mRNA strand?
The mechanism for identifying the start codon (AUG) differs significantly:
In prokaryotes, the small ribosomal subunit binds to a specific nucleotide sequence on the mRNA called the Shine-Dalgarno sequence, located just upstream of the start codon.
In eukaryotes, the small ribosomal subunit typically binds to the 5' cap of the mRNA and then scans along the molecule until it encounters the first AUG codon, which is often situated within an optimal context known as the Kozak sequence.
8. What is an example of how the speed of translation differs between prokaryotes and eukaryotes?
Prokaryotic translation is generally much faster than eukaryotic translation. For instance, an *E. coli* (prokaryote) ribosome can add about 20 amino acids per second to a growing polypeptide chain. In contrast, eukaryotic ribosomes are slower, adding approximately 2 to 4 amino acids per second. This difference in speed is partly due to the simpler, coupled process in prokaryotes and the more complex, regulated machinery in eukaryotes.
