Overview of Microbial Eukaryotes
Living organisms are categorized based on various characteristics, and one classification system revolves around their cellular components, structure, and function. Consequently, organisms, including microorganisms, can be classified as either eukaryotes or prokaryotes. The primary distinction between the two lies in the presence of membrane-bound organelles, including a true nucleus, which is found in eukaryotes but absent in prokaryotes. While it is commonly known that bacteria, for example, are microorganisms with prokaryotic cells, not all microorganisms are prokaryotes. In addition to plants and animals, eukaryotes also encompass microorganisms such as fungi, simple algae, and protozoa. Eukaryotic cells, as mentioned, possess a distinct nucleus containing deoxyribonucleic acid (DNA) as the major component. This nucleus holds the genetic material of the organism. During active cell division, this genetic material organizes into chromosomes, while chromatin refers to its structure during the developmental phase.
Certain microbial eukaryotes, such as various types of algae, possess specialized organelles known as plastids. These structures enable these microorganisms to undergo photosynthesis, utilizing sunlight to produce nutrients similar to plant cells.
Apart from photosynthetic microorganisms, protists can be classified as heterotrophs, acquiring nutrients by seeking food sources outside their cell bodies. Heterotrophs can be further divided into phagotrophs and somatotrophs. Phagotrophs employ the flexibility of their cell bodies to surround and engulf food particles through a process called phagocytosis. Somatotrophs, on the other hand, obtain nutrients by absorbing them through their cell membranes. Interestingly, there are microorganisms like algal dinoflagellates, known as mixotrophs, which exhibit both photosynthetic and phagotrophic abilities.
Mitochondria, more commonly known as the powerhouse of the cell, are responsible for generating the majority of energy in the form of adenosine triphosphate (ATP). These molecules are essential for the organism's internal processes. However, it is worth noting that while most protists possess mitochondria, some that live in oxygen-deprived environments lack this organelle. Instead, they produce energy in hydrogenosomes, which are modified versions of mitochondria. One example of a microorganism that utilizes hydrogenosomes is the parasite Trichomonas vaginalis, which causes a sexually transmitted disease called trichomoniasis.
Many eukaryotes possess special structures such as flagella and cilia. Flagella are hairlike organelles that protozoa, for instance, employ to propel their cell bodies. Cilia, as seen in Paramecium, are shorter appendages and more abundant than flagella. Organisms utilize cilia for synchronized movement.
Microbial eukaryotes reproduce in various ways. Fungi, for instance, engage in vegetative reproduction, commonly known as fragmentation, where smaller fragments break away from the hyphae and develop into new individuals. Another form of reproduction in these microorganisms is asexual reproduction, such as the formation of spores, which is also observed in algae. Furthermore, similar to the gametes of animals and plants, fungi and algae can also multiply through sexual reproduction.
Studying Microbial Eukaryotes
In today's era, modern technologies in microbial research enable the easy identification and detection of microbial eukaryotes. One example is metagenomic sequencing, which allows researchers to sample all the genes present in a complex sample of organisms. Another technique is targeted next-generation sequencing, which focuses on sequencing a specific region of the genome, making sample identification feasible. These techniques are commonly employed in microbial research to develop medicines and diagnostic models targeting disease-causing microorganisms.
