Stem Cells + Totipotency Flashcards
What are totipotent cells?
Totipotent cells are cells which can mature into any body cell
What is an example of a totipotent cell (from women)?
An example of a totipotent cell is a single fertilised egg
What happens to totipotent cells after they differentiate?
Totipotent cells differentiate and become specialised for a particular function
Why do different types of cells, such as mesophyll and muscle cells, perform specific functions despite containing the same DNA?
This is because during the process of cell specialisation, only some genes are expressed.
This means only part of the DNA of a cell is translated into proteins.
Therefore allowing the cell to only make proteins that it requires to carry out its specialised function
What are some essential proteins produced by all cells, regardless of specialisation?
Proteins required for processes like respiration and membrane synthesis are produced by all cells, as they are vital for basic cell function
What happens to the DNA that is not translated into proteins during cell specialisation?
The unneeded DNA is not translated to conserve energy and resources, preventing the production of unnecessary proteins
How does the cell prevent the expression of unnecessary genes? What are these preventions referred to as?
Cells prevent unnecessary gene expression by stopping transcription (blocking mRNA production) or translation. These are known as controlling factors
Do specialised cells retain all the genes of the organism?
Specialised cells still retain all the genes of the organism
What happens to xylem vessel and red blood cells as they specialise?
They lose their nuclei, and since the nucleus contains the genes, they cannot develop into other cells
Is specialisation reversible in animal cells?
No, specialisation is irreversible in most animal cells
In mature mammals, do any cells retain the ability to differentiate into other cells?
Yes, only a few cells retain this ability, and they are called stem cells
What are stem cells?
Stem cells are undifferentiated, dividing cells that can divide to form identical copies of themselves in a process called self renewal
Where are stem cells found?
Stem cells are found in adult animal tissues
What is self renewal process in stem cells?
Self renewal is when stem cells divide to create an identical copy of themselves, allowing them to be constantly replaced
What are the main sources of stem cells in mammals and where is each source located from? (8 marks)
- Embryonic stem cells
- Umbilical cord blood stem cells
- Placental stem cells
- Adult stem cells
Where do embryonic stem cells come from, and what can they do?
Embryonic stem cells come from early embryos and can differentiate into any type of cell.
Where are umbilical cord blood stem cells derived from, and how are they different from adult stem cells?
They come from umbilical cord blood and are similar to adult stem cells
Where are placental stem cells found, and what do they do?
Placental stem cells are found in the placenta and develop into specific types of cells
Where are adult stem cells found, and what is their role?
Adult stem cells are found in body tissues and are specific to certain organs or tissues, helping to maintain and repair them
How are stem cells classified?
Stem cells are classified according to their ability to differentiate into different types of cells
What are totipotent stem cells?
⇒ Give an example
⇒ State where it is found
Totipotent stem cells are cells which can differentiate into any type of cell
Found in early embryos
The ZYGOTE would be totipotent as it can form all body cells
What happens as totipotent cells divide and mature?
As totipotent cells divide and mature, they become pluripotent stem cells, which are slightly more specialised
What are pluripotent stem cells?
⇒ Where are they found?
⇒ State examples
Pluripotent stem cells are cells that can differentiate into almost any type of cell
Examples include embryonic and fetal stem cells
They are found in embryos
How can pluripotent stem cells be used in medicine?
Pluripotent cells can be used to regrow tissues that have been damaged by accidents or diseases
Give an example of how pluripotent cells can help in case of accidental damage. (burn victim)
Pluripotent cells can be used for skin grafts to treat serious burn damage
Why are pluripotent cells significant in treating disorders?
They provide a potential source of regenerating damaged or diseased tissues, improving recovery and treatment outcomes
What are multipotent stem cells?
⇒ Where are they found?
Multipotent stem cells are cells which can differentiate into a limited number of specialised cells
They are found in adults
What are two examples of multipotent stem cells?
Examples of multipotent stem cells include adult stem cells and stem cells from umbilical cord blood
What are unipotent stem cells?⇒ Where are they from?
⇒ Where are they made in?
Unipotent stem cells are cells that can only differentiate into a single type of cell
They are from multipotent stem cells and are made in adult tissue
What is an example of unipotent stem cells ?
An example of unipotent stem cell is cardiomyocytes, heart muscle cells that can divide to repair heart muscle damage
What are induced pluripotent stem cells? (iPS cells)
iPS cells are pluripotent cells produced from unipotent stem cells
What are iPS cells very similar to?
iPS cells are similar to embryonic stem cells in form and function
How are iPS cells created?
iPS cells are created by inducing genes and transcriptional factors within unipotent cells to express themselves, turning on genes that were previously turned
What does the creation of iPS cells reveal about adult cells?
The creation of iPS cells shows that adult cells retain the same genetic information as embryonic cells, which can be reactivated
What is a key feature of iPS cells?
A key feature of iPS cells is self - renewal, allowing them to divide indefinitely and provide a limitless supply
Why are iPS cells significant in medical research and treatment?
iPS cells could replace embryonic stem cells, addressing many ethical concerns associated with using embryos in research and treatment
