Microscopes and Cellular Organization: Unveiling the Microscopic World
The Microscope
The Microscope: An optical instrument designed to observe extremely small objects, making them visible to the naked eye.
Cell Theory
In 1665, after observations with a compound microscope, it was indicated that cork plant material, apparently homogeneous, is composed of innumerable holes or cells that recalled a honeycomb. Since then, the term “cell” has been widely used. Soon after, Anthony van Leeuwenhoek, with the help of simple microscopes of his own construction, made a series of observations and descriptions of cell samples, such as red blood cells and spermatozoa. All this led to his recognition as the discoverer of the microbial world.
Models of Cellular Organization
- Plasma membrane: It surrounds the cell and through it, exchanges of matter, energy, and information with the exterior occur.
- Cytoplasm: Aqueous material is delimited by the plasma membrane where the organelles and molecules involved in various chemical reactions are located.
- Genetic material: The cellular component responsible for controlling and directing the cell’s operation.
Eukaryotic Organization Model
This model features unicellular organisms such as protozoa and multicellular plants and animals. All eukaryotic cells contain a cell nucleus, with the genetic material containing more than one DNA molecule surrounded by a double membrane, the nuclear membrane, which separates and isolates it from the cytoplasm. Eukaryotic cells have a much more complex cytoplasm than prokaryotes and contain numerous organelles that perform specific functions in the cell.
Organelles
The centrosome is an organelle unique to animal cells, prepared by the nucleus when the cell is in a resting state. Inside, the diplosome is composed of two structures called centrioles arranged perpendicularly and surrounded by a number of microtubules that form the aster, giving the whole a starry aspect.
Ribosomes
Located in the cytosol, attached to the membranes of the endoplasmic reticulum or inside other organelles, such as mitochondria or chloroplasts.
Endoplasmic Reticulum
It is a membranous composition similar to the plasma membrane that forms a complicated network of interconnected tubules and saccules, connected to the Golgi apparatus and the nuclear membrane.
Golgi Apparatus
It is a stack of membranous sacs near the nucleus along with a number of smaller vesicles that appear on the side close to the nucleus and are oriented in the plasma membrane.
Peroxisomes
Membranous vacuoles where oxidation reactions take place to eliminate toxic substances.
Vacuoles
These membranous organelles are present in almost all types of plant cells. They exert pressure on the cell wall, maintaining turgor and preventing the plant from wilting.
Cell Nucleus
An observable structure enclosed by a double membrane with pores, the nuclear membrane, allowing the exchange of substances between the nucleus and cytoplasm. The nucleus can appear in multiple areas, including during cell rest, and distinguishes a central part and a granular-fibrous crust. These are the nucleoli, where ribosomes are manufactured.