Organelles and Their Functions

An organelle, is a structure within a cell, that has a specific function. Although most of us are aware of cells, and the basics of cell structure, not everyone may know (or remember from 6th grade biology) all the cell organelles and their functions. Organelles are found in eukaryotic cells, that is, cells that have a nucleus. Prokaryotic organisms like bacteria and archaea lack a nucleus and the genetic matter floats freely within the cells. The following are the functions of the organelles and the major plant and animal cell differences.

Animal Cell

A typical cell is made up of a cell membrane that contains a nucleus, within a jellylike substance called cytoplasm, which holds together the organelles.

Nucleus
This is often referred to as the 'brain' of the cell. Nucleus functions control all other activities that are carried on within the cell. The nucleus consists of a nuclear membrane, chromatins and a nucleolus, it also contains among other things, chromosomes. There may be one or more nuclei in a cell; a nucleus is absent in prokaryotic cells.

Cell Membrane
Gives structure and shape to the cell and is responsible for holding the organelles together. The cell membrane function includes providing protection and it is selectively permeable in nature, since it has the ability to control what enters and leaves the cell.

Endoplasmic Reticulum
This is a network of tubes, sacs and membranes, responsible for transporting material from one part of the cell to another. There are two types of endoplasmic reticulum; rough endoplasmic reticulum (lined with ribosomes) and smooth endoplasmic reticulum (lacking ribosomes/embedded ribosomes).

Ribosome
Ribosomes are thousands of tiny spherical structures that are made of RNA and protein enzymes. Ribosomes function includes helping out in protein synthesis process.

Mitochondria
Also referred to as the 'Powerhouse' of the cell. Mitochondria is made up of a double layered membrane, the inner part of which consists of folds, called cristae. They are responsible for the breakdown of sugar molecules to release ATP (adenosine triphosphate), which is used to transport energy within the cell for metabolism.

Golgi Apparatus
Made up of numerous layers which form a sac like structure. Golgi apparatus functions include protein packaging and its distribution to other parts of the cell.

Centrioles
Centrioles lie near the nucleus and are made up of nine tube like structures, each of which has three tubules. Centriole function includes releasing spindle like formations that attach to chromosomes during one of the cell division stages.

Lysosomes
Lysosome structure will contain enzymes. Lysosome function includes helping in the breakdown of larger molecules into small parts, also responsible for the transport of waste out of the cell.

Vacuoles
Vacuoles store food and water. They also provide turgor pressure against the cell walls; may additionally store waste material before its transported outside the cell.

Plant Cell

Plant and animal cells differ in the number and structure of the above organelles, but the most fundamental difference in plant cell organelles structure and parts, is the presence of the following:

Chloroplasts
Plants differ integrally from animals in their ability to prepare food within their cells by the process of photosynthesis. This process is carried out by chloroplasts which are small oval structures that contain chlorophyll.

Cell Wall
This is a structure made out of cellulose that provides support to the cell. In combination with the vacuole, which is large in plant cells, the other cell wall function includes controlling the turgidity of the cell.

Peroxisomes
These are types of microbodies found in cells, roughly spherical in shape, which contain enzymes responsible for degradation.

Understanding the working of cell organelles and their functions is a basic part of molecular biology. I hope this article has helped you understand cellular structure and the various different functions of organelles in both plant and animal cells.