Prokaryotic and eukaryotic translation are two cellular processes that use messenger RNA (mRNA) molecules to create proteins. Although the fundamentals of translation are the same in prokaryotic and eukaryotic cells, there are some changes in the specifics of how these activities take place since the two cell types differ structurally and organizationally.
Prokaryotic cells typically consist of a single cell without a genuine nucleus or organelles that are attached to membranes. In prokaryotic cells, translation takes place in the cytoplasm and is closely related to transcription. As a result, translation can start even as mRNA is still being produced.
In prokaryotes, the small ribosomal subunit must first attach to the Shine-Dalgarno sequence on the mRNA before the initiator tRNA containing formylmethionine (fMet) can bind to the start codon, which is typically AUG. The functioning ribosome is then formed by the big ribosomal subunit joining.
All multicellular organisms and some single-celled organisms are eukaryotic cells, which feature a nucleus and a variety of membrane-bound organelles. In eukaryotes, transcription takes place in the nucleus, and the translated mRNA is subsequently moved to the cytoplasm.
The small ribosomal subunit of eukaryotic cells binds to the 5′ cap of the mRNA before scanning the mRNA until it comes across the start codon (AUG). The start codon is bound by the initiator tRNA that contains methionine (Met). The functioning ribosome is subsequently formed by joining the big ribosomal subunit.
As a result of the different cellular architectures of these two types of cells, while the general process of translation is conserved between prokaryotic and eukaryotic cells, there are differences in the initiation process, the involvement of ribosome-binding sites, and the handling of mRNA structure.
|
S.No. |
Aspect |
Prokaryotic Translation |
Eukaryotic Translation |
|
1 |
Location of Translation |
Cytoplasm |
Cytoplasm |
|
2 |
Ribosomes |
70S ribosomes |
80S ribosomes |
|
3 |
Start Codon |
AUG (formyl-Met) |
AUG (Met) |
|
4 |
Initiating tRNA |
fMet-tRNAfMet |
Met-tRNAiMet |
|
5 |
Shine-Dalgarno Sequence |
Present (ribosome binding) |
Absent |
|
6 |
Kozak Sequence |
Absent |
Present (initiation site) |
|
7 |
Methionine Usage |
Formyl-Met initially |
Regular Met initially |
|
8 |
Polycistronic mRNA |
Common |
Rare |
|
9 |
Transcription Coupling |
Common |
Rare |
|
10 |
Post-Transcriptional Mods |
Minimal |
Extensive |
|
11 |
mRNA Structure |
Simple |
Complex (introns, exons) |
|
12 |
tRNA Splicing |
Not required |
Often required |
|
13 |
Transcription Location |
Concurrent |
Nucleus |
|
14 |
5′ Cap Structure |
7-methylguanosine cap |
|
|
15 |
Translation Initiation |
fMet-tRNAfMet recognition |
Met-tRNAiMet recognition |
|
16 |
Polyribosome Formation |
Common |
Less common |
|
17 |
Ribosome Association |
Rapid |
Slower |
|
18 |
Peptide Chain Elongation |
EF-Tu/GTP |
eEF1A/GTP |
|
19 |
Termination Codons |
UAA, UAG, UGA |
UAA, UAG, UGA |
|
20 |
Release Factors |
RF1 and RF2 |
eRF1 and eRF3 |
|
21 |
Ribosome Recycling |
IF3 and RF3 |
eIF3 and eRF3 |
|
22 |
Ribosome Assembly |
50S and 30S subunits |
60S and 40S subunits |
|
23 |
Aminoacylation of tRNA |
Primarily single enzyme |
Multiple enzymes |
|
24 |
Initiation Factors |
IF1, IF2, IF3 |
eIF1, eIF2, eIF3 |
|
25 |
Anticodon Loop Modification |
Rare |
Common (wobble base) |
|
26 |
Antibiotics Targeting |
Streptomycin, tetracycline |
Cycloheximide, puromycin |
|
27 |
Signal Peptide |
Present (for secretion) |
Present (for secretion) |
|
28 |
Ribosome Sensitivity |
Sensitive to diphtheria toxin |
Insensitive to diphtheria toxin |
|
29 |
Ribosome Size |
Smaller |
Larger |
|
30 |
Poly-A Tail Binding |
Absent |
Required for termination |
|
31 |
Ribosome Biogenesis |
Rapid |
Slower |
|
32 |
Splicing Complexes |
Rarely involved |
Commonly involved |
|
33 |
Cap-Dependent Translation |
Less common |
Common |
|
34 |
Cap-Independent Translation |
More common |
Less common |
|
35 |
mRNA Stability |
Short-lived |
Longer-lived |
|
36 |
Ribosomal RNA Types |
23S, 16S, 5S |
28S, 18S, 5.8S, 5S |
Frequently Asked Questions (FAQs)
Q1. What crucial elements are a part of prokaryotic translation?
mRNA, transfer RNA (tRNA) molecules containing amino acids, ribosomes (small and large subunits), initiation factors, elongation factors, and termination factors are among the essential elements.
Q2. How exactly does prokaryotic translation begin?
The start codon AUG is bound to by an initiator tRNA carrying formyl-methionine (fMet), which binds to a specific sequence on the mRNA known as the Shine-Dalgarno sequence. A functional ribosome is created by joining the big ribosomal component.
Q3. How is eukaryotic translation initiated different from prokaryotic translation?
The small ribosomal subunit binds to the mRNA’s 5′ cap in eukaryotes, and the ribosome proceeds to scan the mRNA until it comes to the start codon (AUG). Methionine (Met), not formyl-methionine as in prokaryotes, is carried by the initiator tRNA.
Q4. How do eukaryotic cells make secretory or membrane-bound proteins?
In eukaryotic cells, some ribosomes are connected to the endoplasmic reticulum (ER). These ribosomes create proteins that are meant to be secreted or inserted into membranes right into the ER, allowing for appropriate folding and modification.
Q5. What purpose do post-translational alterations serve in eukaryotic proteins?
The function, location, and stability of eukaryotic proteins can be impacted by post-translational changes like glycosylation, phosphorylation, and proteolytic cleavage.
Q6. Are there any distinctions between prokaryotic and eukaryotic translation in terms of elongation and termination?
Both bacterial and eukaryotic translation share the same fundamental stages of elongation and termination. However, there are some variations in the specific elements at play and the way termination codons are acknowledged.
