8.2.1 Most cells DNA not translated Flashcards
what is the process by which cells develop into a specialised structure suited to the role they are carrying out
cell differentiation
what is differentiation
is the process by which stem cells become specialised.
what is a stem cell
is an undifferentiated cell that can divide by mitosis an unlimited number of times and turn into other specific cell types
what can stem cells do
after dividing can remain as stem cell of divide into specialised cells - differentiation
what is the name for the process by which stem cells can differntatied into more speculated cells
potency
name the 3 types of potency
Totipotency
Pluripotency
Multipotency
what is a totipotent cell?
can divide and produce any type of body cell
embryonic stem cells
How do totipotent cells become specialised
They translate only part of their DNA which results in cell specialisation
where are totipotent cells found
early mammilian embryo - occur for limited time there
why are there no totipotent cells present in the later stages of development
as cells lose their ability to differentiate into any cell type
name and define the three types of stem cells
Totipotent – Can develop into any cell type, including the placenta and embryo.
Pluripotent – Can develop into any cell type excluding the placenta and embryo.
Multipotent – Can only develop into a few different types of cells.
what are pluripotent cells
stem cells that are found in embryos and can become any type of cell
what are pluripotent cells used in
research
treat Hyman disorders
used to regrow damaged cells e.g. burnt skin cells
what are the issues with this treatment
doesn’t work
Stem cells continue to divide to create tumours
ethic issues - moral to make therapeutic clone to make embryos
- using embryos that are destroyed later
what are multipotent and unipotent stem cells?
found in mature mammals and can divide to form a limited number of different cell types
what are examples of multipoint cells
bone marrow cells
difference between multipoint and unipotent cells
multi - can differentiate into a limited number of cells, whereas
unipotent cells can only differentiate into one type of cell.
What happens to totipotent cells during embryonic development?
Certain parts of the DNA are selectively translated so that only some genes are ‘switched on’ in order to differentiate the cell into a specific type and form the tissues that make up the foetus.
Give a unique feature of pluripotent cells and the use of this feature.
They can divide in unlimited numbers and can therefore be used to repair or replace damaged tissue.
What is a unipotent cell? Give an example.
A cell that can only develop into one type of cell. This happens at the end of specialisation when the cell can only propagate its own type. An example is cardiomyocytes (heart cells).
Which types of stem cells are found in embryos?
Totipotent and pluripotent.
Multipotent and unipotent cells are only found in mature mammals.
Give some uses of stem cells.
Medical therapies (e.g. bone marrow transplants, treating blood disorders).
Drug testing on artificially grown tissues.
Research (e.g. on the formation of organs and embryos
How are induced pluripotent stem cells produced?
From mature, fully specialised (somatic) cells. The cell regains capacity to differentiate through the use of proteins, in particular transcription factors.
How can stem cells be used in the treatment of human disorders
- transplanted into patients to divide in unlimited numbers
- then differentiate into required healthy cells (to replace damaged cell)
How are induced pluripotent stem (iPS) cells produced
- Obtain adult somatic body cells from patient
- Add specific protein transcription factors associated with pluripotency to cells so they express genes associated with pluripotency
Transciption factors attatch to promoter regions of DNA, stimulating or inhibiting transcription - Culture cells to divide by mitosis
Once made iPS cells can divide and differentiate into healthy cells to be transplated into the same patient
Positives of using stem cells in treating human disorders
- can divide and differentiate into required healthy cells - save lives
- embryos are often left over from IVF so would otherwise be destroyed
- iPS cells unlikely to be rejected by patients immune system as they are their own cells
- iPS cells can be made without destruction of embryo and adult can give permission
Negatives of using stem cells in treating human disorders
- ethical issues with embryonic stem cells (destruction of a potential life)
- immune system could reject cells and immunosupressant drugs are required
- cells could divide uncontrollably leading to cancer
How are induced pluripotent stem cells made?
-Produced from adult somatic cells
- appropriate protein transcription factors are used to switch on the genes that were swtiched off to make the cell specialized
How do IPS cells overcome ethical issues of using embryonicnstem cells
They dont cause destruction of an embryo and the sdult can give permission
How can pluripotent cells treat human disorders
- they can replaaced damaged cells as they divide in unlimited numbers