Scientists resumed observing and studying real plants and animals during the Renaissance. John Ray introduced a new method of grouping by similarities in appearance. The science of taxonomy is a recent development. One of the first scientists of the Renaissance to advance taxonomy through first hand observations was .

We outline theoretical deficiencies and also practical problems, which result in poor taxonomic work, such as insufficient knowledge of the rules of nomenclature (ICZN), lack of appropriate material for comparison (type material), insufficient knowledge of morphology, inappropriate illustrations, lack of keys or …

Taxonomy (which literally means “arrangement law”) is the science of classifying organisms to construct internationally shared classification systems with each organism placed into more and more inclusive groupings. This organization from larger to smaller, more specific categories is called a hierarchical system.

(1) Any group or rank in a biological classification into which related organisms are classified. (2) A taxonomic unit in the biological system of classification of organisms, for example: a phylum, order, family, genus, or species.

There are now six commonly accepted kingdoms. Each kingdom includes a set of organisms that share similar characteristics. The organisms in each Kingdom are considered biologically distinct from the others. The six Kingdoms are: Archaebacteria, Eubacteria, Fungi, Protista, Plants and Animals.

Eukaryotic cells contain 80S ribosomes in the rough endoplasmic reticulum (membrane bound-ribosomes) and cytoplasm (free ribosomes). They contain 70s ribosomes in mitochondria and chloroplasts. Eukaryotic cells have evolved an endomembrane system, containing membrane-bound organelles involved in transport.

Ribosomes have two main functions — decoding the message and the formation of peptide bonds. These two activities reside in two large ribonucleoprotein particles (RNPs) of unequal size, the ribosomal subunits. Each subunit is made of one or more ribosomal RNAs (rRNAs) and many ribosomal proteins (r-proteins).

A Golgi body, also known as a Golgi apparatus, is a cell organelle that helps process and package proteins and lipid molecules, especially proteins destined to be exported from the cell. Named after its discoverer, Camillo Golgi, the Golgi body appears as a series of stacked membranes.

The endoplasmic reticulum (ER) is a large, dynamic structure that serves many roles in the cell including calcium storage, protein synthesis and lipid metabolism. The diverse functions of the ER are performed by distinct domains; consisting of tubules, sheets and the nuclear envelope.

​Mitochondria Mitochondria are membrane-bound cell organelles (mitochondrion, singular) that generate most of the chemical energy needed to power the cell’s biochemical reactions. Chemical energy produced by the mitochondria is stored in a small molecule called adenosine triphosphate (ATP).

The nucleus controls and regulates the activities of the cell (e.g., growth and metabolism) and carries the genes, structures that contain the hereditary information. Nucleoli are small bodies often seen within the nucleus. The gel-like matrix in which the nuclear components are suspended is the nucleoplasm.

Lysosomes function as the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself.

Inside the nuclear membrane is the nucleoplasm, which main function is to store DNA and facilitate an isolated environment where controlled transcription and gene regulation is enabled. The nucleoplasm contains several non-membrane bound substructures,such as nuclear bodies and nuclear speckles.

There are certain Animal cells that do not have a nucleus. These are Erythrocytes (RBC) and Platelets. These are blood cells. Mature erythrocytes lack a nucleus and thus it does not show the presence of chromosomes also and hence cannot divide.

Nucleus is the brain of the cell and controls most of its functions. Thus without a nucleus, an animal cell or eukaryotic cell will die. Without a nucleus, the cell will not know what to do and there would be no cell division. Protein synthesis would either cease or incorrect proteins would be formed.