Stem Cells 6.5 Flashcards
Differentiation
When a cell is specialised and changes its structure in order to carry out a specific function. Most of these cells will have the same DNA and differentiation is just the expression of some genes in a cell’s genome.
Stem Cells
Undifferentiated cells that have been produced from mitosis or meiosis and have the potential to become a differentiated cell.
What happens to cells when they become specialised?
They stop being able to divide as they enter the Go phase.
What happens in stem cells aren’t controlled
Either they won’t divide fast enough to replace tissue which will result in ageing, or they will divide too fast which will lead to tumours forming which is cancer.
The potency of a cell
This is the cells ability to differentiate into many different types of cells. The more variety, the more potent the cell is.
Totipotent
These can differentiate into any type of cell. It is an embryo (zygote) and the first few cells after it’s division.
Pluripotent
These can form any tissue type and are present in early embryos
Multipotent
These can only differentiate into certain types of cells within a certain type of tissue.
Where are blood cells derived from?
The bone marrow
Replacement of red and white blood cells
Because red blood cells don’t have a nucleus, they only live for 120 days so stem cell colonies in the bone marrow produce 3 billion per kg a day.
Neutrophils only have a lifespan of 6 days so the bone marrow produces 1.6 billion per kg a day.
Sources of animal stem cells
Embryonic stem cells are totipotent for the first few days after conception, and then they become pluripotent.
Tissue (adult) stem cells are found in specific places like the bone marrow and are multipotent.
You can use an umbilical cord to get pluripotent stem cells
Sources of plant stem cells
The stem cells of a plant are called meristems and are found in meristematic tissue which is wherever the plant grows. They are located between the xylem and phloem which is the vascular cambium. They are pluripotent.
Some uses of stem cells
They have the potential to treat heart disease, type 1 diabetes, Alzheimer’s and Parkinson’s. They are already used for burns, drug trials.
Ethics
Using embryos is controversial as people argue that it’s a life so you’re taking one life to save another and therefore it’s murder. To solve this they are trying to artificially make adult stem cells pluripotent, or use unbiblical chords which are only multipotent.
