CGE: Stem Cells Flashcards
Totipotent stem cells
Can mature into any type of body cell.
All specialised cells come from what?
Stem cells
Where can stem cells be found?
In the embryo and in some adult tissues.
Where are totipotent stem cells present?
Only present in mammals in the first few cell divisions of an embryo.
What happens to totipotent stem cells in mammals after the first few cell divisions?
They become pluripotent.
Can still specialise into any cell in the body, but lose the ability to become cells that make up the placenta.
Stem cells in adult mammals are either…
Multipotent or unipotent
Pluripotent stem cells
Stem cells that can specialise into any body cell, but have lost the ability to differentiate into cells that make up the placenta.
Multipotent stem cells
Stem cells that can differentiate into a few different types of cell.
Unipotent stem cells
Stem cells that can only differentiate into one type of cell.
Can mature into any type of body cell.
Totipotent stem cells
Stem cells that can specialise into any body cell, but have lost the ability to differentiate into cells that make up the placenta.
Pluripotent stem cells
Stem cells that can differentiate into a few different types of cell.
Multipotent stem cells
Stem cells that can only differentiate into one type of cell.
Unipotent stem cells
Describe the process of stem cells becoming specialised:
- Under the right conditions, some genes are expressed and others are switched off.
- mRNA is only transcribed from specific genes.
- mRNA from these genes is translated into proteins.
- Proteins modify the cell - determine the cell structure and control cell processes.
- Changes to the cell produced by proteins = cell is specialised.
Give an example of a cell becoming specialised:
- Stem cell produces new cell where the genes for haemoglobin production are expressed.
- Other genes, eg. those involved in removing the nucleus, are expressed too.
- Many other genes are not expressed.
- Specialised red blood cell forms.
Cardiomyocytes
Heart muscle cells that make up the heart tissue.