Stem Cells Flashcards
What is a stem cell
A cell that can divide (by mitosis) an unlimited amount of times
What does each new cell produced by the division of a stem cell have the ability to do
It has the ability to remain a stem cell or develop into a specialised cell (by a process called differentiation)
What is the definition of potency
They ability of stem cells to differentiate into specialised cells
What are totipotent stem cells
Stem cells that can differentiate into any cell type found in an embryo as well as extra embryonic cells.
What is the potency of a zygote
It’s totipotent as are the embryonic cells up to the 16th cell stage of human embryo development.
What is pluripotent
Pluripotent stem cells are embryonic stem cells that can differentiate into any cell type found in an embryo, but aren’t able to differentiate into extra embryonic cells.
What is multipotency
They are adult stem cells that have lost some of the potency associated with embryonic stem cells and are no longer pluripotent.
What happens as tissues, organs and organ systems develop
The cells become more and more specialised.
What happens to adult cells and why
Having differentiated and specialised to fulfil particular roles, most adult stem cells gradually lose the ability to divide until they are no longer able to.
What are adult stem cells
A small number of stem cells that remain to produce new cells for essential processes of growth cell replacement and tissue repair.
What is the potency of adult stem cells
They are only able to produce a limited range of cell types - therefore they are multipotent adult stem cells (they can only differentiate into blood cells)
Where can multipotent stem cells be found in the body
They can be found throughout the body (bone marrow, skin, gut, brain)
What are erythrocytes
Red blood cells specialised to aid oxygen transport around the body
because red blood cells lack a nucleus how are more produced
Because they lack a nucleus they can’t perform mitosis to give rise to new cells; this means that erythrocytes directly form from adult stem cells in the bone marrow to maintain the red blood cell count in the blood.
What are the changes in cell structure when the adult stem cells specialise into erythrocytes
-> loss of nucleus
-> shape change to form a biconcave disc
-> increase production of haemoglobin protein
-> increase in membrane flexibility
What are neutrophils
A type of white blood cell that is specialised to destroy pathogens by phagocytosis
How are neutrophils produced
They are produced from the same adult stem cells as the erythrocytes
What are some changes that occur when the adult stem cells differentiate into neutrophils
-> indentations form in the nucleus giving it a lobed structure
-> Production of hydrolytic enzymes increases
-> Lysosomes that contain hydrolytic enzymes accumulate
-> membrane flexibility increases
What are meristems
Meristems are where plant stems cells are found
Two examples of differentiated cells that are from the meristem
Xylem and phloem
Where are the specialised cells that make xylem and phloem up found
They are located in the meristems and the cambium cells are found between regions of xylem and phloem tissue in plant stems and roots.
What are some changes that occur when cambium differentiates into xylem
Deposition of lignin in cell walls
Loss of cytoplasm
Loss of end walls
What are some changes that occur when cambium differentiates into phloem
Reduction in cytoplasm volume
Loss of organelles
End walls -> sieve tubes
What are the three potential uses of stem cells in the treatment of disease
Repair damaged tissue
Treat neurological conditions
Research developmental biology
What is the first factor to consider when evaluating the use of embryonic stem cells in medicine (1)
Ethical concerns about the use of embryonic stem cells which have the potential to develop into adult humans.
What is the first factor to consider when evaluating the use of embryonic stem cells in medicine (2)
Any adult stem cells used in medical treatment could cause and immune response unless they are a close tissue match
What is the first factor to consider when evaluating the use of embryonic stem cells in medicine (3)
Stem cells have the ability to divide indefinitely and if this division becomes uncontrollable it can lead to cancers.
What are the three sources of tissue damage
Accidental damage
Degenerative disease
Autoimmune conditions
How can stem cells be used to repair damaged tissue
Stem cells can be encouraged to differentiate into a damaged cell type and used to repair damaged tissue.
What are the four potential uses of stem cells to repair damaged tissue
skin cells to treat burn patients
Neurones to repair damaged spinal cord
Pancreas cells to treat type 1 diabetes
Retina cells for the treatment of macular degeneration in the eye
What can brain cells and neurones be affected by
Some diseases which can affect the body’s ability to coordinate responses to stimuli
How can stem cells be used to treat neurological conditions
Stem cells can be used to generate new neurones in order to treat symptoms of these conditions.
What is an example of stem cells to treat neurological conditions
Replacing damaged brain cells in Alzeihmer’s and Parkinson’s disease
What do embryonic stem cells have the ability to and what does this allow
To differentiate into embryos, allowing scientists to study the developmental stages of the early embryo
What can stem cells being used for developmental biology also provide
Important information about
Developmental problems
The effects of medicines on embryos
