The key difference between bacteria and eukaryotes is that the bacteria lack a true nucleus and membrane-bound organelles while the eukaryotes possess a true nucleus and membrane-bound organelles.
The cell is the basic functional and structural unit of all living organisms. Depending on the basic structure of the cell, there are two basic categories of organisms namely prokaryotes and eukaryotes. Prokaryotes are unicellular organisms with simple cell structures. They include two main groups; Bacteria and Archaea. On the other hand, eukaryotes have complex cellular structures with well-organized cells. They include protists, fungi, plants and animals. Since both bacteria and eukaryotes are living organisms, they share some similarities such as having a cell membrane, ribosomes, DNA that carries genetic information, etc. However, since bacteria are prokaryotes, bacteria and eukaryotes show many structural and functional differences with eukaryotes. This article intends to highlight the difference between bacteria and eukaryotes.
CONTENTS
1. Overview and Key Difference
2. What are Bacteria
3. What are Eukaryotes
4. Similarities Between Bacteria and Eukaryotes
5. Side by Side Comparison – Bacteria vs Eukaryotes in Tabular Form
6. Summary
What are Bacteria?
All bacteria are prokaryotes and therefore possess all the fundamental characteristic features of prokaryotes. Bacteria are ubiquitous, hence present in everywhere including the extreme environments such as deep sea caves, volcanic rims, hot springs, and deep within glaciers where no other life would exist. Consequently, they have very simple cellular structures with no membrane-bounded organelles and a true nucleus. Basically, this feature makes them different from eukaryotes. Furthermore, all bacteria are unicellular. They possess 70S ribosomes.
Moreover, they contain one circular chromosome as their genetic material. Besides, they possess extra-chromosomal DNA circles called plasmids. Plasmids are important in genetic engineering as vectors that act as vehicles to deliver genes into host organisms.
Figure 01: Bacteria
Bacteria are in different shapes and different sizes. Coccus, Bacillus, spirochetes and Vibrio are four common shapes of bacteria. Moreover, many bacteria are harmless while a small percentage is pathogenic.
What are Eukaryotes?
Eukaryotes are one of the two major categories of living organisms. They have a complex cell structure with a true nucleus and membrane-bound organelles such as mitochondria, chloroplasts, ER, Golgi bodies, etc. The eukaryotic genome represents by a number of chromosomes composed of DNA molecules tightly bound with histone proteins. Unlike in bacteria, the eukaryotic genome is present inside the nucleus.
Figure 02: Eukaryotes
Furthermore, eukaryotes are unable to live in harsh environments, unlike bacteria. Eukaryotic ribosomes are larger and composed of the 40S small subunit and 60S large subunit. Generally, eukaryotes are multicellular. However, there are few types of unicellular organisms as well. Eukaryotes include protozoa, algae, fungi, plants and animals.
What are the Similarities Between Bacteria and Eukaryotes?
- Bacteria and eukaryotes are living organisms.
- They grow, develop and reproduce.
- Furthermore, they die when they complete their life spans.
- Also, both possess a cellular organization.
What is the Difference Between Bacteria and Eukaryotes?
Bacteria lack a true nucleus and membrane-bound organelles while eukaryotes possess a true nucleus and membrane-bound organelles. This is the key difference between bacteria and eukaryotes. Furthermore, one other major difference between bacteria and eukaryotes is that the bacteria are unicellular while eukaryotes are mostly multicellular. However, certain eukaryotes are unicellular.
Moreover, a further difference between bacteria and eukaryotes is that the bacteria possess a single chromosome, and it is present in the cytoplasm. But, eukaryotes have multiple chromosomes, and they are present inside the nucleus. Also, when considering the size of a cell of each group, the bacterial cell is smaller than a eukaryotic cell. Hence, it is also a difference between bacteria and eukaryotes. Besides, bacteria have small ribosomes which are the 70S while eukaryotes have large ribosomes which are 80S. Therefore, this is another difference between bacteria and eukaryotes.
The below infographic presents more details on the difference between bacteria and eukaryotes.
Summary – Bacteria vs Eukaryotes
In summarizing the difference between bacteria and eukaryotes; bacteria are tiny, ubiquitous microorganisms that belong to prokaryotes. They are simple unicellular organisms. Furthermore, they lack a true nucleus and membrane-bound organelles. On the other hand, eukaryotes are complex organisms. They are generally multicellular. Eukaryotic cells possess a true nucleus and membrane-bound organelles. Furthermore, bacteria have a single chromosome in the cytoplasm while eukaryotes have multiple chromosomes inside the nucleus. Also, bacterial ribosomes are small and 70S while eukaryotic ribosomes are large and 80S.
Reference:
1. Vidyasagar, Aparna. “What Are Bacteria?” LiveScience, Purch, 23 July 2015. Available here
2. “Eukaryote.” Wikipedia, Wikimedia Foundation, 21 Jan. 2019. Available here
Image Courtesy:
1.”3662695″ by qimono (CC0) via pixabay
2.”Eukaryota diversity 2″By Osmia rufa couple (aka), André Karwath, Hans Hillewaert et al (CC BY-SA 2.5) via Commons Wikimedia