Week 1 Flashcards
What are the two key properties of a stem cell?
- Differentiation – The ability to develop into one or more specialized cell types.
- Self-renewal – The ability to replicate and maintain the stem cell pool.
Where do stem cells reside in the human body?
- Bone marrow – Hematopoietic stem cells.
- Skin & gut lining – Rapidly dividing stem cells.
What is the key difference between mitosis and meiosis?
Mitosis: Produces 2 genetically identical diploid cells.
Meiosis: Produces 4 genetically unique haploid cells.
What are the three possible fates of a stem cell?
- Quiescence – Reversible inactivity.
- Cell Division – Symmetric or asymmetric.
- Apoptosis/Senescence – Cell death due to aging or DNA damage.
What is the difference between quiescence and senescence?
Quiescence: Reversible inactivity due to lack of nutrients.
Senescence: Irreversible aging/DNA damage leading to cell death.
How are progenitor cells different from stem cells?
Stem cells can self-renew and differentiate into multiple types, while progenitor cells have limited self-renewal and are committed to a specific lineage.
What are the two broad categories of stem cells?
- Embryonic Stem Cells (ES) – Derived from blastocysts -After fertilization and until the 8-cell embryo
* All cells can be viewed as stem cells
* Derived from the blastocyst stage of the embryo - Adult Stem Cells – Found in mature tissues, responsible for repair and regeneration
-Present in most (probably all) adult tissues
* Role: provide a source of replacement cells for the tissue of which they are a part
* Exist throughout life
* Capable of generating lineage-specific differentiation
* Ideally not accumulate damaging mutations
* Therefore, many adult stem cells spend a large duration in quiescence
What are the levels of stem cell potency?
- Totipotent – Can differentiate into all cell types.
- Pluripotent – Can differentiate into all embryonic cell types.
- Multipotent – Can differentiate into multiple but limited cell types.
- Unipotent – Can differentiate into only one cell type.
How is the stem cell niche important for function?
The niche provides signals via the extracellular matrix (ECM), growth factors, and cytokines, regulating stem cell activity and differentiation.
Niche or the “environment” in which the stem is in is crucial to its regulation
* Niche is composed of different components for example the extracellular matrix (ECM)
* Physical orientation of a stem cell in its niche can also influence its regulation
What are induced pluripotent stem (iPS) cells?
Adult cells genetically reprogrammed to behave like embryonic stem cells, offering potential in regenerative medicine.
How do animals regenerate lost organs or limbs?
- Stem cell implantation.
- Pre-primed cell implantation.
- Activation of endogenous stem cells.
What is autotomy?
The ability of animals to self-amputate a body part as a defense mechanism, common in salamanders, lizards, and the African spiny mouse.
- this process allows the full regeneration of the missing appendage
What is the difference between dedifferentiation and transdifferentiation?
Dedifferentiation: Reverting to an earlier cell state.
Transdifferentiation: Switching to a completely different lineage.
What is the most regenerative organ in the human body?
The liver has the highest regenerative capacity in humans.
What are the three main strategies for regeneration in medicine?
- Implantation of stem cells
- Implantation of pre-primed cells
- Stimulation of endogenous stem cells
What are the key differences between vertebrate and invertebrate regeneration?
Invertebrates (e.g., flatworms) can regenerate entire bodies, while vertebrates (e.g., salamanders) have limited regenerative capacity, mainly for limbs or organs.
What is the significance of Hydra in stem cell research?
Hydra was the first experimental model of regeneration, demonstrating the ability to regrow body parts through continuous stem cell activity.
What factors influence the regulation of stem cells?
- Extrinsic factors (growth factors, cytokines, ECM, niche environment)
- Intrinsic factors (gene transcription regulation, mRNA stability, protein translation)
What is the role of cytokines in stem cell regulation?
Cytokines are signaling molecules that help control immune responses, inflammation, and stem cell differentiation.
What is the difference between a progenitor cell and a stem cell?
Stem cells can self-renew indefinitely, while progenitor cells have a limited capacity for replication and are already committed to a specific lineage.
What is the role of chemokines in stem cell function?
Chemokines direct stem cell migration and localization within tissues, influencing immune responses and tissue repair.
What is the importance of extracellular matrix (ECM) in stem cell regulation?
The ECM provides structural and biochemical support, influencing cell adhesion, migration, and differentiation.
What is the purpose of stem cell quiescence?
Quiescence helps stem cells avoid excessive proliferation and potential DNA damage, maintaining long-term regenerative capacity.
What is the role of transcription factors in stem cell regulation?
Transcription factors control gene expression, guiding stem cell self-renewal and differentiation.
What is the function of transient amplifying cells?
These are rapidly dividing progenitor cells that arise from stem cells and differentiate into specialized cell types.
What are the key benefits of regenerative medicine?
- Tissue and organ replacement
- Reduced reliance on organ transplants
- Improved treatment for degenerative diseases
How does tissue-specific stem cell demand vary?
Different tissues require varying levels of stem cell activity depending on regeneration needs, e.g., skin and gut renew rapidly, while the brain has limited regeneration.
What are the major sources of adult stem cells?
- Bone marrow
- Adipose tissue
- Neural tissue
- Muscle tissue
What are the ethical concerns surrounding embryonic stem cell research?
The destruction of embryos raises ethical debates, leading to alternative approaches like induced pluripotent stem (iPS) cells.
How was Drosophila first cloned?
In 2004, researchers at Dalhousie University used nuclear transfer to implant donor nuclei into an enucleated embryo, creating a cloned fly.
Are animal cells genetically equivalent?
When nuclei from differentiated frog eggs were transferred to unfertilized enucleated frog
eggs, tadpoles could form
When adult sheep cells were fused with enucleated eggs and implanted them into
surrogate mothers
* A cloned lamb (named Dolly) was born
* A genetically identical copy of the donor adult sheep
Thus, adult cells are genetically equivalent; cell differences result from differential gene
expression
Evidence that Differentiated Plant Cells Are Genetically Equivalent
All cells in a plant are genetically equivalent—they contain the same genes
* Some branch cells can de-differentiate and form root cells
* Entire plants can be grown from a single adult cell
