3.5.7 Control of Gene Expression (AQA A2 Biology)

Overview of gene expression on the AQA A2 level biology syllabus. Includes totipotency, cell specialisation, stem cells, embryonic stem cells and the regulation of transcription and translation. 

HideShow resource information
  • Created by: Imogen
  • Created on: 01-05-14 18:17
Preview of 3.5.7 Control of Gene Expression (AQA A2 Biology)

First 288 words of the document:

3.5.7 Gene expression is controlled by a number of features
TOTIPOTENCY AND CELL SPECIALISATION
What are totipotent cells?
Totipotent cells are cells which can mature into any body cell.
KEY TERMS
Specialisation: The process of a totipotent cell becoming specialised to
express one gene.
Specialised: The cell has a specific function e.g. alpha and beta cells in
the islets of Langerhans.
Stem cells: Undifferentiated dividing cells that occur in adult animal
tissues.
Where are totipotent cells?
Embryos ­ embryonic stem cells are found when the egg is fertilised,
none of the cells are specialised. They have to differentiate into their
functions.
Stem cells ­ found in the small intestine, bone marrow and skin of
humans.
Plants ­ in plants, many of the cells remain unspecialised. They can
develop in vitro or into organs that the plant needs. (Taking a root cell
from a plant and placing it in the right conditions can create an identical
clone of the plant it was take from.)
How does a cell become specialised?
A cell becomes specialised by only expressing
certain genes. If it expressed all the genes in
the DNA then it would be a waste of time and
energy. All cells express certain genes e.g.
chemicals for respiration. This specialisation
can change the appearance of a cell due to
the protein genes that are being expressed.
How are genes prevented from being expressed?
Regulating transcription so there's no mRNA to be translated
Regulating translation so the genetic code is not revealed
Ethics Surrounding Embryonic Stem Cells
1

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Gene expression is controlled by a number of features
FOR AGAINST
Embryo at this stage has no Undermines respect for human
resemblance to a human being life. Playing `god'.
and is just cells. Lead to older foetuses/babies
Wrong to allow human being used.
suffering which can be Lead to human cloning,
prevented. research could be used in other
Why destroy embryos after countries.
IVF? Wrong to use as a means to an
end.…read more

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »