Given your understanding of the processes behind gene expression, analyse the link between gene expression and the repair of body tissues. Write an account of how this happens.
Gene.png
A Generic gene, here shown in relation to a chromosome.


Gene Expression
Genes are said to be expressed if they are able to produce a full functioning protein. Genes may be present but not expressed, e.g. if they are repressed by another gene.


laceration.jpg
A sample laceration wound.

...And Repair of Body Tissues
When the body is damaged or injured, it is the expressed genes of the body that enable proteins to make their repairs on the damaged tissue. These genes provide the proteins, enzymes, and hormones necessary to heal the wound. However, as one ages, repressor genes inhibit the expression of genes necessary to repair body tissues - in other words, we heal faster and more completely when we are younger.


The DNA Replication Cycle and the Necessity of Repressor Genes
Genes that repair body tissue are also an essential part of the DNA replication cycle which maintains a healthy cycling of cells. However, repressors that inhibit these repair genes are also an essential part of the cycle - tumour suppressor genes and the like prevent uncontrolled cell division (which results in cancerous growth).

‚Äč Cancerous Growths and the Necessity of Repressor Genes
Cancerous growths (or tumours) result from uncontrolled division of cells which grow into one of the various kinds of tumours, malignant or benign. Normal mitosis will automatically produce cancer because mitosis precipitates unchecked cell division. The existence of repressor genes that prevent constant, unchecked cell division prevents human beings from becoming infected with cancerous growths. Repressors are DNA-binding proteins that bind to the DNA segment known as the operator. By binding here, the repressor prevents the RNA polymerase from creating messenger RNA. Repressors can be negated by inducer molecules that force the repressor to "let go" of the operator of the DNA - hence the repressor/inducer system is essentially an example of a feedback mechanism.


How Gene Expression Results in the Repair of Body Tissues
In gene expression, a segment of DNA is "switched on" to produce a polypeptide.
The polypeptide is then manipulated into the required protein.
The protein is transported and manipulated so as to become either a component of cytoplasm or to function as an enzyme and control the production of other cellular molecules.


Scientific Studies
Evidence has shown that which genes are "switched on" and which genes are "switched off" determines the type of cell and its functioning.
If mutation occurs, gene expression is altered and the maintenance and repair of tissues can be disrupted.


Thus, gene expression is inextricably linked to the formation of body tissue and the process of cell division (mitosis), as a disturbance in the healthy process of gene expression can lead to faulty mitosis, and thereon to cancerous growths.

Glossary of Terms

Expressed Genes: Genes capable of producing a fully functioning protein.
Polypeptide:
Proteins formed by the union of three or more amino acids.
A chain of linked amino acids. When folded in a particular three-dimensional configuration, it becomes a protein.
A peptide containing anywhere between 10 and 100 molecules of amino acids. Peptides can either be small proteins or part of a protein.

Cytoplasm:
The protoplasm of a cell excluding the nucleus; is full of proteins that control cell metabolism.

Definition Bibliography, In Case Stuff Is Wrong and Mrs Bannerman Attempts Murder...
Cytoplasm: [[wordnetweb.princeton.edu/perl/webwn]]
Polypeptide:
www.nutros.com/nsr-05zzz.html
profiles.nlm.nih.gov/DJ/Views/Exhibit/narrative/glossary.html

www.biotechnologyonline.gov.au/topitems/glossary.html