Cellular biology, also sometimes referred to as cell biology or cytology, is the study of the structure and functions of cells. Cells are the basic building blocks of all known life forms so understanding the makeup and structure of organisms is imperative in order to gain a greater understanding of biological studies. Elements of molecular biology are also present in the studies of how cell components interact with each other as well as microscopic elements.
Cells are made up of smaller components which allow functions to be carried out within the cell called organelles. Cells and their organelles in turn make up larger structures such as tissue, organs and organ systems in more complex forms of life. Within the cells of all living organisms contains the components needed to allowing life to grow, adapt and thrive on Earth.
The primary function of a cell is to allow organization within a life form. The variety of cells in an organisms largely determines the complexity of the life form. Single celled organisms are limited in the size they are able to grow to because they lack the basic structure to expand beyond their inherent size.
Although there are a variety of types of cells, the two most common types explored in biology class are plant cells and animal cells, both of which have distinct structures and functions.
Types of Cells
There are two main types of cells which are seen throughout life. These are classified as prokaryotes and eukaryotes. What is the difference between a prokaryote and a eukaryote? Well that is one which many students ask who first begin learning about biology. The simplest answer is that a prokaryote lacks a nucleus, mitochondria and the membranes that separate organelles from the cytoplasm. Essentially all the components within a prokaryotic cell float freely and are not bound but therefore cannot serve to carry out specialized functions.
Prokaryotic cells are relatively primitive by nature as they do not contain complex sub structures which carry out designated functions like in eukaryotes. The two kingdoms which make up these creatures are bacteria and archaeans. Due to the simple nature of the cell structure, prokaryotes are able to inhabit a wider range of geography and often are found living inside other organisms. Instead of having individualized organelles which carry out specific tasks in the cell, a prokaryotic cell is more of a slurry of cell materials which are organized in no particular order. This cell structure is believed to be more ancient than it’s eukaryotic counterpart due to its relatively primitive design.
Eukaryotic cells are ones which contains organelles, a subunit which is divided from the rest of the cell with a membrane or lipid bilayer. The most important component contained within a eukaryote is the nucleus which houses the DNA and RNA functions of the cell. Eukaryotic organisms are much more complex than prokaryotic organisms however as such are unable to span in the larger geo distribution available to single celled organisms. Although both animal and plant cells differ from each other vastly, they are both classified as eukaryotic because they have advanced organelles which help to carry out basic functions for the cell to maintain its life cycle for the organism.
Animal cells are some of the most complex and contain an array of organelles which are comprised to carry out functions to allow the overall cell to maintain life and growth. Reproduction for eukaryotes are done through a process called mitosis which consists of the organelles splitting into two mirrored parts prior to the membrane splitting to produce the new copy. The structures and organelles that set an animal apart on the cellular level are:
An organelle that controls the organization of microtubules in an assembly line like procedure to ensure proper cell division can occur.
The gel like substance that surrounds the nucleus and is contained within the membrane which functions to move organelles and materials as well as degrading cellular waste.
The endoplasmic reticulum or ER serves a variety of functions and is split into two distinct parts. The first is layered with ribosomes and is referred to as the rough ER while the second lacks these ribosomes and is referred to as the smooth ER. The rough endoplasmic reticulum creates proteins which are moved to the smooth endoplasmic reticulum. From the smooth ER lipids and carbohydrates are created to help transport the vesicles to other destinations.
A plant’s cells are distinctly differentiated from animal cells because they are surrounded by a cell wall or membrane made of cellulose. The organelles contained within an plant cell differ from those found in their animal counterparts. Plant cells contain chloroplasts which are responsible for creating the green pigment seen in most plants as well as carrying out the functions of photosynthesis.