Bacteria are one of the largest representatives of the microbiological world. The 3 domain classification system by Carl Richard Woese (1990) duly credited them by assigning a separate domain (Domain Bacteria). Bacteria along with archaea constitute the prokaryotic form of life on this Earth. Students are inducted into the ‘prokaryotic versus eukaryotic debates’ very early on in their scientific careers. Yet, the lack of clarity about how and why they differ from each other is evident and disappointing.
The bacterial life forms are a prolific display of nature’s intricate engineering. Their marked presence is ubiquitous beyond our imaginations. You prompt a location, and they would already be living there for millions of years. From Earth’s most hostile environments to your yogurt, from your gut biome to mother’s breast milk, and from volcanic sites to Antarctica’s frozen icebergs, bacteria have occupied incredible niches that only they are capable of thriving in.
Doesn’t this make one wonder how these simple yet highly enabled life forms manage to occupy such a wide range of habitat options?
The ability to carry out all of the essential life processes is coded in the genome of bacterial species. Understanding the genetic code of bacterial species and its manifestation in the form of bacterial structures thus becomes vital. The cellular structure of prokaryotic life bears striking differences from eukaryotic one. Therefore, for educators to deliver all of this data in one teaching session must be very challenging.
In an attempt to simplify it for them, we at Labster provide a short simulation on Comparing Bacterial Structures and tips to make this topic engaging for students. Educators can find this article of real help as it highlights the blocks encountered by students in comprehending different bacterial structures. It also underscores the criteria to look for when comparing structures of different bacterial species. We provide some practical solutions to resolve all of these complexities. By the end, we’ll share why a virtual lab simulation will prove useful not only for your students but also for you as an educator to deliver concepts more efficiently.
Figure: Interactive GIF from Labster's Comparing Bacterial Structures simulation.
There are 3 reasons why students are apprehensive about the topic of bacterial structures. Acknowledging these roadblocks is the first step toward making the topic more approachable.
The idea of bacterial structures feels abstract and conjectural
Since bacteria are already invisible to the naked eye, studying their minute structures that students can’t see, feel, or dissect can be demoralizing. They sound like conjectures that one is just expected to cram and write down in their exams or tests. Failing to see any real-world utility of learning about bacterial nucleoids, membranes, shapes (rod, coccoid, spiral), and occurrence (pairs, clusters, chains), students find it hard to stay inquisitive about the subject and tend to lose interest in this memory game.
The terminologies are lengthy and complex
The terminologies involved in the structural biology of bacteria like peptidoglycans, lipoteichoic acids, lipopolysaccharides, etc are complex. The names of lipids, carbohydrates, protein channels, etc that constitute the bacterial cell structure are quite lengthy too. Memorization of such terms and their definitions come along as a monotonous job that eventually depletes the students’ interest in the subject. No wonder why these terminologies often slip from the minds of experienced scientists too.
3. Lack of reasoning and visualization while teaching
Students feel the presence of an obvious void when such a topic is discussed in classroom teaching. The void is majorly described to be a lack of objective reasoning behind all of these structures by their educators. Teaching a structure without telling its importance and role in a biological system is of no use. Also, since classroom teaching is restricted to textual 2-D diagrams, students also report a void in the visualization of these structures. Imagining how different types of bacteria (gram-positive and gram-negative) assemble their basic structures in a biologically distinct manner can be quite time-consuming and taxing for students.
Developing interest by reasoning and retrospective learning
When we compare a prokaryotic bacterial cell with a eukaryotic cell, we can notice some striking differences. Rather than just listing out these differences for your students, it is a bigger responsibility for you as an educator to provide reasons. Instilling a practice of rational thinking and questioning the importance of each and every cellular structure can make microbiology lessons more intriguing and practical.
Making your students ruminate over classical questions like ‘why is bacterial cell devoid of so many cell organelles that a eukaryotic cell possesses?’ or ‘why do bacterial cells possess flagella or pilia’ can successfully kindle their interest in the subject. Educators should strive to explain answers to these questions by drawing analogies. (Example: Since the singular cell membrane of bacterial cells is capable enough to perform all the functions that different membranous cell organelles perform in a eukaryotic cell, there is no need for special organelles in the former.)
Practicing situation-based discussions can also prove beneficial. You can put forth instances where one or the other essential bacterial structure is deleted from the cell. Then you can ask your students to explain the consequences of this deletion (structure’s absence) on the cell functioning. This type of retrospective learning can benefit your students by shaping their logical reasoning and enhancing their scientific aptitude. You can also use the Comparing Bacterial Structure simulation for your students. It uses a gamification element for placing different cell structures into the correct type of cell (bacterial-vs-eukaryotic)! Students can learn as they play around with this feature.
Figure: This picture shows the gamification element from the Comparing Bacterial Structures simulation by Labster. Your students can look at the names of different cellular components and then decide which cell (bacterial/eukaryotic) they should place them in. It is available for High School and University / College classes.
2. 'Storytelling’ is a means of leaving knowledge imprints in your student’s mind
It is very difficult for a young brain to remember an endless list of structures that comprise a biological cell. And when the biological cells are of different types (prokaryotic bacterial cell, eukaryotic animal or plant cell, and so on), it further increases their struggle. Therefore, associating the ‘stories’ behind the discovery of these structures with the ‘some essential role, terminology’ can help in easy memorization.
You can take lead from some of these examples:
Nucleoid story: Hans Ris was one of the earliest scientists to distinguish between the genetic material of bacteria and eukaryotes. His meticulous exploration and documentation of the similarities between the genetic material of ‘cyanobacteria/primitive plant/blue-green algae’ and the ‘chloroplasts of green algae- a eukaryote’ were a phenomenal breakthrough. He coined the term genophore for the single, circular, and dsDNA of the bacteria which later came to be known as the nucleoid. By rendering such stories, you can make the concept of nucleus-vs-nucleoid clearer to your students.
Plasmid story: Bacterial cells possess extrachromosomal genetic material called plasmids that serve special purposes like transferring traits (antibiotic resistance), fertility factors (for conjugation), coding for bacteriocins (proteins that kill other bacteria), etc. The term plasmid was coined by Joshua Lederberg in 1952 while he was working on Salmonella bacteria and its P22 virus along with his PhD student Norton Zinder. While the plasmids were decoded by Joshua only in 1952, the lesser known story is of the fertility (F) plasmids that were discovered and coined by his wife, Ether Lederberg in the 1940s itself. Remembering plasmids by this short story would be easier for your students.
Gram stain story: Hans Christian Gram while working on the lung tissue sections of pneumonia-succumbed patients first used his gram staining technique. In an attempt to stain only the causal bacterial species i.e. the Streptococcus pneumoniae and not the eukaryotic lung cells, he devised his own staining method using Crystal Violet stain (1° stain), iodine solution (mordant), and last step of ethanol wash (decolorizer). His stain worked well for many bacterial species but failed against the typhoid bacilli. This led to the discovery “gram positive and gram negative concept”. Since Salmonella typhii (the causal organism of typhoid) possesses a very thin peptidoglycan layer which is also discontinuous due to interlinkage adherences between the outer and inner membranes of the bacteria, the gram stain doesn’t stain these species.
This discovery story can help you in delivering the concept of gram staining. It can serve as an effective concept-building strategy that compares different bacterial structures like cell wall (peptidoglycan layer), outer membrane (lipopolysaccharides, teichoic acids), etc in various types of bacteria.
3. Relating the significance of their structural variety to their wide habitat choices
Showing your students how bacteria are one of the most marvelous results of nature’s engineering can ignite their interest in this topic. The peculiarities in the bacterial structure make them exquisitely capable of living in the most hostile, inhospitable, and inhabitable parts of the Earth. You can quote examples like these:
With a greater capacity to assimilate carbon and nitrogen and unique chemoautotrophic ability, halophilic bacteria are gifted to survive in extremely dry and saline Chile's Atacama Desert. The environment of this desert almost resembles that on Mars.
You can quote the example of another distinctively-abled bacteria ‘Candidatus desulforudis audaxviator’. Due to its exceptionally large genome size and distinguished ability to derive food and hydrogen from the radioactive decay of minerals like gold, uranium, etc, this bacterium actively inhabits deep gold mines.
Such a session with your students would not only ensure a lucid flow of information but will also ensure that the interest of your students is equally maintained.
Figure: This snippet from Comparing Bacterial Structures simulation by Labster shows the different structures of different types of bacteria (coccus in picture). It is available for High School and University / College classes.
4. Making it objective, schematic and well-exemplified
Since there are so many features based on which one can compare different bacterial species, it is important that educators simplify this for their students. A good flowchart should serve the purpose. After that, you can use examples of those particular bacteria which are related to real-life use or problems.
Types based in shape: Coccus, bacillus, filamentous, spiral,coccobacillus
Pneumonia causing bacteria=Coccus (Streptococcus pneumonia)
Yogurt setting bacteria= Bacillus (Lactobacillus acidophilus)
Types based on gram staining: Gram positive, gram negative
UTI causing bacteria= Gram positive (Enterococci spp.)
Vinegar producing bacteria=Gram negative (Acetobacter spp.)
Figure: This snippet from Comparing Bacterial Structures simulation by Labster shows the structure of the plasma membrane. It can be useful while explaining the same for bacterial membranes. It is available for High School and University / College classes.
5. Use virtual lab simulations
Since this topic is essentially content-heavy without a lot of information to memorize, you can make your class more conducive by using the Comparing Bacterial Structures simulation provided by Labster. Teachers can make more insightful points as students are rendered with better visual and interactive engagement options. The 3D simulations help them better understand the assembly of bacterial cells and how it varies from one bacterial type to another.
Your students don’t have to struggle to imagine different types of structures that a bacterium possesses as our simulation along with gamification elements come to the rescue. By using this way of active and immersive teaching, our virtual learning platform takes an advent in the field of Science to make the upcoming scientists thorough with the “basics of their respective subjects”.
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