8. Explain each of the following terms in relation to DNA - Leaving Cert Biology - Question 8 - 2005

Transcription is the process in which the information in a specific segment of DNA is copied into RNA. This RNA serves as a template for protein synthesis, allowing the genetic information to be expressed. During transcription, only one strand of the DNA is used to create the messenger RNA (mRNA).

A typical plant used for DNA extraction could be a banana (Musa spp.) due to its soft tissue and high DNA content.

Chopping the tissue and blending it serves to break down the plant cell walls, releasing the cellular contents, including DNA. This physical disruption increases the surface area for subsequent chemical reactions involved in DNA extraction.

The blender should typically run for a few seconds only, preferably no more than 6 seconds. This prevents excessive damage to the DNA molecules while adequately breaking down the tissue.

Washing-up liquid helps to break down cell membranes and membrane components, releasing the DNA into the solution. It works by disrupting lipid bilayers of the cell and nuclear membranes.

Sodium chloride is used to clump (protect) DNA and to remove proteins, which separates the DNA from other cellular debris. Salt facilitates the precipitation of DNA by stabilizing the negative charges on the DNA backbone.

A protease enzyme is a type of enzyme that breaks down proteins. It cleaves the peptide bonds within proteins, resulting in smaller peptides or amino acids.

A protease enzyme is used in the DNA extraction process to break down proteins that are associated with DNA, such as histones. This ensures that the DNA can be separated cleanly from proteins and cellular debris.

The alcohol (ethanol) is used when it is cold, often at ice-cold temperatures. This helps to precipitate the DNA out of solution, as DNA is less soluble in cold alcohol, allowing it to be visualized.