B2.3 Cell Specialisation Flashcards
What are stem cells?
Unspecialised cells with two key qualities: self-renewal and potency
Self-renewal allows them to continually divide and replicate, while potency enables them to differentiate into specific cell types.
What is self-renewal in stem cells?
The ability of stem cells to continually divide and replicate
This characteristic allows stem cells to maintain their population.
What does potency refer to in stem cells?
The capacity to differentiate into specific cell types
As a cell differentiates, it loses the ability to form alternative cell types.
What are the three main types of stem cells?
- Totipotent
- Pluripotent
- Multipotent
These types are categorized based on their differentiation potential.
What are totipotent stem cells?
Stem cells that can form any cell type and develop into entirely new organisms
Example: zygotes.
What are pluripotent stem cells?
Stem cells that can form any cell type arising from the three germ layers
Example: inner cell mass of the blastocyst.
What are multipotent stem cells?
Stem cells that can only form a number of closely related cell types
Example: bone marrow stem cells.
What are embryonic stem cells?
Totipotent and pluripotent stem cells considered to be derived from embryos
They have greater potency for therapeutic use.
What are adult stem cells?
Multipotent stem cells found in adults, such as those in bone marrow
They have ethical advantages and a lower chance of graft rejection.
What is a key advantage of embryonic stem cells?
Greater potency, allowing them to treat more conditions
However, ethical issues arise from their use.
What is a key advantage of adult stem cells?
Less ethical issues and lower chance of graft rejection
Involves the use of the patient’s own cells.
How can the potency of adult stem cells be increased?
By triggering the expression of specific genes via nuclear reprogramming
Induced pluripotent stem cells are difficult and expensive to create.
What are stem cell niches?
Sites within the body where a pool of adult stem cells are maintained
They prepare for future proliferation and differentiation.
Where are some locations of stem cell niches in the human body?
- Bone marrow
- Hair follicles
- Heart
- Intestines
- Brain
These locations provide environments for stem cell maintenance.
What is the role of haemopoietic stem cells in the bone marrow?
They give rise to different types of blood cells
Examples include erythrocytes, leucocytes, and thrombocytes.
What is a common use of bone marrow transplants?
To replace the haemopoietic stem cell niche following chemotherapy for leukemia
This is important for restoring blood cell production.
What role do epidermal stem cells in hair follicles play?
Involved in cyclic bouts of hair growth, skin innervation, vascularisation, and wound repair
They could be harvested for skin tissue regeneration or hair regrowth.
What is differentiation?
The process during development whereby newly formed cells become more specialised and distinct from one another as they mature.
What do all cells of a multicellular organism share?
An identical genome – each cell contains the entire set of genetic instructions for that organism.
What causes a cell to differentiate into different cell types?
The activation of different instructions (genes) within a given cell by chemical signals.
What is the zygote’s role in embryonic development?
An unspecialised zygote will divide and develop into a mass of specialised cells (early embryo) via differentiation.
What drives the differentiation process in embryos?
The release of gene regulating chemicals (transcription factors) called morphogens.
How does the concentration of morphogens affect cells during development?
Cells closer to the morphogen source receive higher concentrations, activating more genes, while those further away receive lower concentrations, activating fewer genes.
What determines the impact of a morphogen?
Its relative concentration, which decreases as the morphogen diffuses from the source cell.
