Prokaryotes vs. Eukaryotes

All living organisms can be grouped into two types based on their fundamental cell structure. They are prokaryotes and eukaryotes, and the cells they possess are called prokaryotic cells and eukaryotic cells.

Prokaryotes are primitive organisms lacking a nucleus and membrane-bound organelles. The term ‘prokaryote’ is derived from the Greek words ‘pro’, meaning ‘before’ and ‘karyon’, meaning ‘kernel’. Together it means ‘before nuclei’. In contrast, eukaryotes are advanced organisms with a well-defined nucleus and membrane-bound organelles. The term ‘eukaryotes’ is derived from the Greek words ‘eu’, meaning ‘good’ and ‘karyon’, meaning ‘kernel’, meaning ‘true nuclei’. The eukaryotes are thought to have originated from the prokaryotes about 2.7 billion years ago.

Compare and Contrast Prokaryotic and Eukaryotic Cells

Although they share some common characteristics, prokaryotic and eukaryotic cells differ in most aspects, such as cell size, shape, organization, and life cycle, including reproduction. The main differences are given below.

What is the Difference between Prokaryotic and Eukaryotic Cells

Basis	Prokaryotic Cell	Eukaryotic Cell
1. Examples	Cells of bacteria, archaea or archaebacteria, and cyanobacteria or blue-green algae	Cells of plants, animals, fungi, algae, and protozoa (protists)
2. Type	Unicellular	Unicellular or multicellular
3. Size (in diameter)	0.1 to 5.0 μm	10 to 100 µm
4. Type of Organization	Simple	Complex
5. Cell Wall	Usually present. Made of peptidoglycan or mucopeptide	Usually absent. If present (in plants and fungi) made of cellulose
6. Nucleus	Absent. Instead, have a nucleoid that is devoid of the membrane	Present and membrane-bound
7. DNA	Circular, double-strandedFound freely in the cytoplasm. Naked (not bound to proteins). Little repetitive DNA and no introns	Linear, double-stranded. Found within the nucleus. Bound to histone proteins. A large amount of repetitive DNA and introns
8. Chromosome Number	Single haploid (n) chromosome	Paired diploid (2n) chromosome
9. Plasmid	Present.	Absent.
10. Ribosome type	70S type, with 50S and 30S subunits. Smaller in size compared to the eukaryotic cell	80S type, with 60S and 40S subunits. Larger in size compared to the prokaryotic cell
11. Mitochondria	Absent	Present
12. Chloroplast	Absent. Chlorophyll scattered in the cytoplasm	Present in plants and algae
13. Endoplasmic Reticulum	Absent	Present
14. Golgi Apparatus	Absent	Present
15. Lysosomes	Absent	Present
16. Peroxisomes	Absent	Present
17. Mesosome	Present	Absent
18. Centrosome	Absent	Present except for flowering plants
19. Cytoskeleton	Absent	Present
20. Flagella	Microscopic in size. Simple in structure, made of protein, flagellin	Submicroscopic in size. Complex in structure, with 9+2 arrangement of microtubules
21. Cilia	Absent	Present
22. Mode of Reproduction	Asexual	Mostly sexual
23. Cell Division	Asexually by binary fission but can exchange genetic information by conjugation, transformation, and transduction	Through mitosis
24. Generation Time	Shorter (20 to 60 minutes) than eukaryotes	Longer (12 to 24 hours) than prokaryotes
25. Metabolic Rate	Higher than eukaryotes	Lower than prokaryotes
26. Respiration	Via cytoplasm membrane	Via mitochondria
27. Electron Transport Chain	Found in the cell membrane	Found in the mitochondrial membrane
28. DNA Replication	Occurs in the cytoplasm Has one origin of replication	Occurs in the nucleus. Has multiple origins of replication
29. Transcription and Translation (Protein Synthesis)	Occurs simultaneously. Both occur in the cytoplasm	Occurs one after the other. Transcription occurs in the nucleus, and translation in the cytoplasm
30. Gene Expression (Regulation)	Expressed in groups called operons	Expressed individually
31. Cytoplasmic Streaming	Absent	Present
32. Glycocalyx	Present in capsule or slime layer	Present in cells lacking a cell wall

What do Prokaryotes and Eukaryotes have in Common

Both prokaryotic and eukaryotic cells are alike in some ways and share some common features that are given below:

Plasma Membrane, an outer covering that allows selective entry and exit of substances in and out of the cell, is found in both cell types. Their fundamental composition in forming a lipid bilayer with embedded proteins is also the same.
Both contain cytoplasm, a jelly-like fluid that fills the cell’s entire interior, where all other cellular components are found.
DNA is the genetic material in both cell types.
In both, ribosomes help in protein synthesis.

FAQs

Q1. Are viruses prokaryotic or eukaryotic?

Ans. Viruses are not cells and thus are neither a prokaryote nor a eukaryote.

Q2. Is Amoeba prokaryotic or eukaryotic?

Ans. Amoeba, being a protist, are eukaryotes.

Q3. Is yeast prokaryotic or eukaryotic?

Ans. Yeast, being fungi, is a eukaryote.

Q4. Are eubacteria prokaryotic or eukaryotic?

Ans. Eubacteria, or ‘true’ bacteria, are a class of bacteria and thus are prokaryotes.

Q5. Is E. coli prokaryotic or eukaryotic?

Ans. E. coli,being bacteria, is a prokaryote.

Q6. Are human cells prokaryotic or eukaryotic?

Ans. Human cells have a true nucleus and membrane-bound organelles and thus are eukaryotes.

Q7. Is Euglena prokaryotic or eukaryotic?

Ans. Euglena, being protist, are eukaryotes.

Q8. Are Cyanobacteria prokaryotic or eukaryotic?

Ans. Cyanobacteria or blue-green algae lack membrane-bound organelles and well-organized nuclei and thus are prokaryotes.

Q9. Did eukaryotes evolve from prokaryotes?

Ans. Yes. Eukaryotes originated at least 2.7 billion years ago, following almost 1 to 1.5 billion years of prokaryotic evolution.

Q10. How is protein synthesis different in prokaryotes and eukaryotes?

Ans. Prokaryotic protein synthesis uses 70S ribosomes in comparison to 80S ribosomes in eukaryotes. Protein synthesis in prokaryotes is a continuous process with transcription. On the other hand, in eukaryotes, protein synthesis starts after transcription is complete.

Q11. Is Elodea prokaryotic or eukaryotic?

Ans. Elodea is a plant genus, and thus is a eukaryote.

Q12. Are onion cells and cheek cells prokaryotic or eukaryotic?

Ans. Onion cells and cheek cells are eukaryotic cells because they possess membrane-bound organelles and a well-organized nucleus.

Q13. Is mold prokaryotic or eukaryotic?

Ans. Mold, being fungi, is a eukaryote.

Q14. Is HIV eukaryotic or prokaryotic?

Ans. HIV, being a virus, is neither a prokaryote nor a eukaryote.

Q15. Is Streptococcus prokaryotic or eukaryotic?

Ans. Streptococcus is a bacterial genus and thus is a prokaryote.

Q16. Are cancer cells prokaryotic or eukaryotic?

Ans. As cancer cells are found only in multicellular organisms, which are eukaryotes, they are eukaryotic cells.

Q17. Is a red blood cell prokaryotic or eukaryotic?

Ans. All red blood cells, including rodent red blood cells, are eukaryotic because they have a true nucleus and membrane-bound organelles.

Q18. Is a fish prokaryotic or eukaryotic?

Ans. Fish cells, including sharks, are eukaryotic because they have a true nucleus and membrane-bound organelles.

Q19. Is Monera prokaryotic or eukaryotic?

Ans. Monera is a kingdom that includes bacteria and archaea. They have a prokaryotic cell organization.

Q20. Is Saccharomyces prokaryotic or eukaryotic?

Ans. Saccharomyces is a genus of fungi, including many yeast species. They are thus eukaryotes.

Q21. Is Spirillum prokaryotic or eukaryotic?

Ans. Spirillum is a bacterial genus and thus is a prokaryote.

Q22. Is Vibrio cholera prokaryotic or eukaryotic?

Ans. Vibrio cholera, being bacteria, is a prokaryote.

References
- 1. Prokaryotes Vs. Eukaryotes: What Are the Differences? – Thoughtco.com
  2. 47 Differences between Prokaryotes and Eukaryotes – Microbenotes.com
  3. Prokaryotic versus Eukaryotic Cells – Ib.bioninja.com.au
  4. Prokaryotic vs. Eukaryotic Cells: What’s the Difference? – Livescience.com