Phylogeny of Life

Phylogeny of Life

Introduction

Organisms evolve day by day into different historical lineages as they change over time. This ideology implicates that various species emerge from previous forms through descent. All creatures, whether little or large, are connected by the passage of genes. There are three life domains; bacteria, Eukaryota, and archaea. This study encompasses the evolutionary relationship between different species basing upon their similarities and differences in their physical and genetic make-up.

Morphology in Domains

Bacteria

Bacteria display diverse shapes called morphologies, which are determined by the cell wall and the cytoskeleton. Their cells are one-tenth of eukaryotic cells, and only a few are visible to naked eyes. Among the tiniest members of bacteria are the Thiomargarita namibiensis, which are only half a millimeter long. While some bacteria take a spherical shape called cocci, others are rod-shaped and are referred to bacilli. Some others like vibrio are slightly curved rods, spiral-shaped, or tightly coiled in the case of spirochaetes. These shapes determine their ability to acquire nutrients, escape predators, or attach to surfaces.

Bacterial species exist as single cells while others associate in featured patterns. For instance, Neisseria forms diploid cells while Streptococcus configure in chains. Other bacteria group to establish multicellular structures like in the case of elongated filaments of Antinobacteria. In attachment to surfaces, bacteria have dense aggregations, biofilms and microbial mats that range a few micrometers in terms of thickness. Biofilms-bacteria have an intricate appearance of cells and extracellular components that form secondary structures that allow efficient diffusion of nutrients.

Eukaryota

Eukaryotic cells are either unicellular or multicellular, depending on the type of organism. These cells comprise of the plasma membrane, cytoplasm, Golgi bodies, and ribosomes, among other organelles. The cell shapes are not defined and may be bounded or spherical shaped. The form is determined by functional adaptations, a viscosity of protoplasm, and rigidity of the cell membrane. The size of cells varies within broad limits, for instance. Some plant cells may be viewed with unaided eyes. The smallest cell sizes are observed in bacteria, where they range between 0.1 micrometers to 1 micrometer.

Archaea

Archaean cells have unusual shapes that are maintained by both their cell wall and the prokaryotic cytoskeleton. They range from 0.1 to 15 micrometers. They assume shapes such as spheres, rods, spirals, and plates. There exist other morphologies such as irregularly shaped lobed cells, needle-like filaments that are in Sulfolobus. In other genera of archaea, they lack a cell wall; hence their cells have irregular shapes like in the case of Thermoplasma. Some species form filaments of up to 200 micrometers long and are prominent in biofilms. Archaea have multicellular colonies called cannulae that connect them into a dense agglomeration. These structures allow communication and provide a base for nutrient exchange.

Conclusion

The three life domains have distinct features that determine their morphologies. However, there exists a resemblance in terms of sizes and shapes. For instance, both bacteria and archaea have spiral-shaped cells and possess needle-like filaments that are present in biofilms. Studying such morphological patterns helps us understand the connection between plants, animals, and micro-organisms.