Introduction

What exactly does cell division mean? How do we get from one cell to two cells? The simple answer is that a single cell divides to form two so-called daughter cells. For the daughter cells to have the complete set of proteins they need to live and function normally; both must receive the genetic material that contains the blueprint for all those proteins. In other words, both daughter cells must receive the full complement of DNA, in the form of chromosomes. Additionally, the parent cell must have sufficient cytoplasm, membranes, and organelles to split evenly and distribute to the two daughter cells. Once these requirements have been met, the cell can begin the process of dividing into two.

Learning

Cell Division occurs in biological systems to perform the following functions:

• Transmission of Genetic Information
• Growth and Development
• Sexual/Asexual Reproduction

Let us now look at each of these functions in more detail...

Transmission of Genetic Information

• As we have discussed in prior modules, the molecule of heredity/genetic information is DNA.  DNA is packaged into a set of discrete chromosomes which are stored in the nucleus in eukaryotic cells.
• Each chromosome consists of a very long sequence of nucleotides, the order of which provides the blueprint for the assembly of proteins.  Each segment of the chromosome used to produce proteins is called a gene. Genes are the discrete units of inheritance.
• To survive after cell division, each daughter cell must receive a complete set of genes, and therefore a complete set of chromosomes.  To prepare for this process, prior to cell division, each cell must make a complete copy of each set of chromosomes to distribute to the progeny cells.

Growth and Development

• Following cell division, each progeny cell will contain a complete set of genetic information inherited from the parent cell.  The progeny cells will then begin the process of growing to match the size of the original parent cell.
• Cells in your body belong to specialized tissues where they perform specific functions.  Even though cells found in your muscles contain the same genetic information as those found in your liver, these cell types are quite different in their function.  The process of ‘specialization’ for different cell types is called ‘differentiation’.
• You might be familiar with the concept of stem cells.  Stem cells retain the capacity to divide and to ‘differentiate’ into various cell or tissue types.  It is this unique property which makes stem cells so valuable for treating various diseases.

Sexual/Asexual Reproduction

• Organisms reproduce in one of two ways – sexually and asexually.
• In asexual reproduction, each offspring receives an identical set of genetic material from the parent.  Because of this, each offspring would be considered a ‘clone’ of the parent as well as to each of their siblings.  All prokaryotes (bacteria) as well as some plants and fungi can reproduce asexually.

In sexual reproduction, genetic information is contributed and combined from two parents.  In this case, each parent contributes gametes (examples would be sperm or egg) which fuse together to create a new offspring.  The key distinguishing feature of gametes is that they contain only half the number of chromosomes found in the parent.  This is critical since when the gametes are combined, the new offspring will contain a full, complete set of chromosomes.  Gametes are produced using a type of cell division called meiosis which we will discuss in detail.

Summary

Cell Division occurs in biological systems to perform the following functions:

• Transmission of Genetic Information – To survive after cell division, each progeny cell must receive a complete set of genes, and therefore a complete set of chromosomes.
• Growth and Development –
• Sexual/Asexual Reproduction –
• Asexual reproduction, each offspring receives an identical set of genetic material from the parent.  Because of this, each offspring would be considered a ‘clone’ of the parent.
• In sexual reproduction, genetic information is contributed and combined from two parents.  In this case, each parent contributes gametes (examples would be sperm or egg) which fuse together to create a new offspring.
• Cells in your body belong to specialized tissues where they perform specific functions. The process of ‘specialization’ for different cell types is called ‘differentiation.’

Sources:

“Reproduction at the Cellular Level.” By OpenStax Biology Concepts. Retrieved from https://openstax.org/books/concepts-biology/pages/6-introduction / Licensed under: CC-BY: Attribution

Biology. Authored by: Open Stax. Located at: http://cnx.org/contents/185cbf87-c72e-48f5-b51e-f14f21b5eabd@9.17:1/Biology. License: CC BY: Attribution