MODULE 41

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Questions and Answers

What is a primary characteristic of stem cells?

They can continuously divide and self-renew. (correct)

They do not have the ability to differentiate.

They are highly specialized.

They can only differentiate into one cell type.

What process do stem cells undergo to become more specialized cell types?

Apoptosis

Cellular division

Cellular differentiation (correct)

Synthesis of RNA

Which type of stem cells can differentiate into any of over 200 cell types?

Unipotent stem cells

Totipotent stem cells

Pluripotent stem cells (correct)

Multipotent stem cells

What does asymmetric stem cell division result in?

One stem cell and one differentiated cell Signup and view all the answers

What distinguishes professional stem cells from facultative stem cells?

Professional stem cells are permanent; facultative can dedifferentiate. Signup and view all the answers

Which statement about totipotent stem cells is correct?

They can form a new individual. Signup and view all the answers

Which stem cell type is considered to have the least differentiation能力?

Unipotent Signup and view all the answers

In what situation do adult stem cells typically remain quiescent?

In healthy, non-injured tissue Signup and view all the answers

What term is used to describe cells that can form many types of cells and are typically pluripotent?

Embryonic germ cells Signup and view all the answers

What is a key characteristic of adult stem cells compared to embryonic germ cells?

They are typically multipotent or unipotent. Signup and view all the answers

What ethical concern is associated with using embryonic stem cells?

They involve the destruction of embryos. Signup and view all the answers

Which process is used to create induced pluripotent stem cells?

Transducing adult cells with stem cell-associated genes Signup and view all the answers

What is the hierarchical flow of differentiation for stem cells?

From stem cells to progenitor cells and then to mature cells Signup and view all the answers

What does the term 'quiescent' imply about most adult multipotent stem cells?

They remain inactive until stimulated. Signup and view all the answers

What happens to the CBC stem cells if they are lost?

They are replaced by +4 stem cells Signup and view all the answers

What is a common source of cord blood stem cells?

Umbilical cord blood Signup and view all the answers

What is a disadvantage of induced pluripotent stem cells compared to embryonic stem cells?

Their generation process requires optimization. Signup and view all the answers

Which stem cells are located at the bottom of the intestinal crypt?

CBC stem cells Signup and view all the answers

Which of the following signals promote stem cell self-renewal?

Wnt signaling Signup and view all the answers

What characterizes the +4 stem cells?

They are quiescent and damage-resistant Signup and view all the answers

What is the default situation in the intestinal epithelium?

Actively proliferating stem cells continuously replenish dying differentiated cells Signup and view all the answers

What role do TA cells play as they move up the crypt?

They differentiate into various cell types Signup and view all the answers

Which type of signaling increases as one moves up the intestinal crypt?

Hedgehog signaling Signup and view all the answers

What effect does increased HES1 expression have on cell differentiation in Notch-high cells?

Promotes differentiation to absorptive cells Signup and view all the answers

What can occur through dedifferentiation in the intestinal crypt?

A progenitor becomes a multipotent stem cell Signup and view all the answers

How do Notch-low cells influence Dll expression?

By increasing Atoh1 expression Signup and view all the answers

What characteristic is true of induced pluripotent stem cells?

They have the potential to differentiate into any cell type Signup and view all the answers

What role does Notch signaling play in the transit-amplifying (TA) cell compartment?

It regulates differentiation pathways through lateral inhibition Signup and view all the answers

What differentiates intestinal stem cells from other stem cell types?

They exhibit unique signaling mechanisms and differentiation pathways Signup and view all the answers

What outcome results from increased expression of HES1 in Notch-high cells?

Decrease in Dll expression Signup and view all the answers

What is the primary role of Notch signaling in the TA compartment?

It controls intestinal cell differentiation through lateral inhibition Signup and view all the answers

How does decreased HES1 expression influence Notch-low cells?

It results in increased differentiation to secretory cells Signup and view all the answers

What is the relationship between Atoh1 and Dll expression in Notch-low cells?

High Atoh1 expression reinforces Notch-low, Dll-high phenotype Signup and view all the answers

What distinguishes intestinal stem cells from other stem cell types?

They have unique characteristics and specific differentiation pathways Signup and view all the answers

What is a characteristic of multipotent stem cells?

They are somewhat differentiated but can form several tissues. Signup and view all the answers

What distinguishes totipotent stem cells from pluripotent stem cells?

Only totipotent cells can form a new individual. Signup and view all the answers

What is asymmetric stem cell division primarily responsible for?

Producing one stem cell and one cell for differentiation. Signup and view all the answers

Which statement best describes quiescent adult stem cells?

They remain inactive until stimulated by external signals. Signup and view all the answers

Which of the following describes dedifferentiation?

A return to a less specialized, more 'stem-like' state. Signup and view all the answers

Which type of stem cells are considered professional stem cells?

Lg5+ CBC cells in the intestine Signup and view all the answers

What happens during progenitor division?

It leads to the expansion of the progenitor cell population. Signup and view all the answers

What is the primary function of embryonic stem cells?

To create any cell type in the body. Signup and view all the answers

What is the primary advantage of induced pluripotent stem cells over embryonic stem cells?

They bypass the ethical controversies of using embryonic stem cells. Signup and view all the answers

What type of stem cells are embryonic germ cells categorized as?

Pluripotent Signup and view all the answers

Which step is NOT involved in generating induced pluripotent stem cells?

Introduce genetic modifications to all existing adult cells Signup and view all the answers

What is a key characteristic of adult stem cells compared to other types of stem cells?

They generally have a restricted ability to produce various types of cells. Signup and view all the answers

What happens to stem cells as they progress through differentiation?

They lose stemness and become more differentiated. Signup and view all the answers

Which of the following describes the pathway of adult stem cells?

They tend to be quiescent until stimulated to differentiate. Signup and view all the answers

Which type of stem cell is derived specifically from parts of an embryo that will produce gametes?

Embryonic germ cells Signup and view all the answers

What is a significant requirement for the generation of induced pluripotent stem cells?

Transfecting adult cells with viruses carrying stemness-related genes. Signup and view all the answers

What is the primary role of CBC stem cells in the intestinal crypt?

To actively proliferate and replace differentiated cells Signup and view all the answers

Which stem cell type functions as a reserve and may be recruited upon intestinal damage?

+4 stem cells Signup and view all the answers

What happens to TA cells as they move up the intestinal crypt?

They differentiate into various mature cell types Signup and view all the answers

Which signaling pathway is primarily associated with promoting differentiation as one moves up the crypt?

Hedgehog signaling Signup and view all the answers

What defines the main characteristic of +4 stem cells compared to CBC stem cells?

They are quiescent and short-lived under normal conditions Signup and view all the answers

Which statement is true regarding the dedifferentiation process in the intestinal crypt?

It involves a progenitor regaining stemness and reverting to a multipotent state Signup and view all the answers

Where are the CBC stem cells primarily located within the intestinal structure?

Near the stem cell niche at the bottom of the crypt Signup and view all the answers

What is the effect of BMP signaling in the context of intestinal stem cell activity?

It acts as an antagonist to stem cell proliferation Signup and view all the answers

What is the role of HES1 in Notch-high cells during differentiation?

It leads to the suppression of Atoh1 expression. Signup and view all the answers

How do Notch-low cells influence the expression of Dll?

They increase Dll expression through decreased HES1 levels. Signup and view all the answers

What is the expected outcome of increased Atoh1 expression in Notch-low cells?

Induction of secretory cell lineage development. Signup and view all the answers

What is the significance of Dll expression in Notch-high and Notch-low cells?

Notch-high cells exhibit low Dll expression while Notch-low cells exhibit high Dll expression. Signup and view all the answers

What characterizes the interactions between Notch and Dll in intestinal cell differentiation?

Notch-Dll interactions lead to competitive differentiation fates. Signup and view all the answers

What best describes the term 'dedifferentiation'?

The transformation of a specialized cell back to a more stem-like state. Signup and view all the answers

Which of the following best describes asymmetric stem cell division?

Produces a stem cell and a cell that is committed to differentiate. Signup and view all the answers

Which statement accurately reflects the properties of multipotent stem cells?

They have limited differentiation capability but can form several tissue types. Signup and view all the answers

How do professional stem cells differ from facultative stem cells?

Professional stem cells always remain as stem cells while facultative can dedifferentiate. Signup and view all the answers

Which of these stem cell types is the least capable of differentiating into multiple lineages?

Unipotent stem cells. Signup and view all the answers

What is the result of a progenitor division?

It expands the progenitor cell population. Signup and view all the answers

Which stem cell type can give rise to any cell in the body, including extraembryonic tissues?

Totipotent stem cells. Signup and view all the answers

What is a key characteristic of adult stem cells in contrast to embryonic stem cells?

Adult stem cells are often quiescent until activated. Signup and view all the answers

Which type of cells are derived from parts of the embryo that would eventually produce gametes?

Embryonic Germ Cells Signup and view all the answers

What is a notable ethical concern regarding the use of embryonic stem cells?

The controversy surrounding their source Signup and view all the answers

Which type of stem cells can typically produce fewer types of differentiated cells?

Adult Stem Cells Signup and view all the answers

What process is involved in creating induced pluripotent stem (iPS) cells?

Transducing adult cells with stem cell-associated genes Signup and view all the answers

What limitation currently exists regarding induced pluripotent stem cells?

The reprogramming process requires optimization Signup and view all the answers

In the differentiation pathway of stem cells, what does 'loss of stemness' refer to?

Progression towards fully differentiated mature cells Signup and view all the answers

What distinguishes Induced Pluripotent Stem Cells from embryonic stem cells?

They are created from adult differentiated cells Signup and view all the answers

What is the primary role of adult stem cells in tissues?

To maintain tissue homeostasis and repair Signup and view all the answers

What role do +4 stem cells play in the intestinal crypt?

They are quiescent and can be recruited to become CBC stem cells upon damage. Signup and view all the answers

Which type of signaling promotes stem cell self-renewal in the intestinal crypt?

Bmp antagonists Signup and view all the answers

What is the main differentiating feature of CBC stem cells compared to +4 stem cells?

CBC cells are actively proliferating. Signup and view all the answers

What process allows progenitor cells to revert back to a multipotent stem cell state?

Dedifferentiation Signup and view all the answers

What happens to the CBC cells as they proliferate and differentiate?

They move up the crypt and become mature cell types. Signup and view all the answers

Which characteristic is true of CBC stem cells?

They are damage-sensitive and capable of rapid proliferation. Signup and view all the answers

How is the proliferation and differentiation of intestinal stem cells regulated?

By cell signaling pathways, including Wnt and Bmp. Signup and view all the answers

What is the primary function of TA cells as they move up the crypt?

To differentiate into various mature cell types. Signup and view all the answers

Study Notes

Stem Cell Definitions and Characteristics

Stem cells can divide continuously (self-renewal).
Stem cells can differentiate into various cell types/tissues.
Stem cells are unspecialized (blank slate).
Stem cells can divide and self-renew for extended periods.
Stem cells can differentiate into more specialized cell types.
Adult stem cells are typically inactive until needed; some continuously proliferate, self-renew, and differentiate (e.g., Lg5+ CBC cells in the intestines).
Cellular differentiation is the process of changing from one cell type to another (usually more specialized), controlled by cell signaling pathways.
Dedifferentiation is changing to a less specialized, more stem-like cell.

Stem Cell Division and Differentiation

A stem cell (A) can divide symmetrically (1) to create two stem cells.
A stem cell (A) can divide asymmetrically (2) to create one stem cell (for maintenance) and one differentiating cell.
A progenitor cell (B) is a cell that has started to differentiate.
Progenitor cell division (3) creates more progenitor cells.
Terminal differentiation (4) results in a fully differentiated cell.

Stem Cell Types

Totipotent cells (e.g., early human embryo cells—1–3 days) can form a new individual.
Pluripotent cells (e.g., embryonic stem cells and some human blastocyst cells—5–14 days) can form any of over 200 cell types.
Multipotent cells (fetal tissue, cord blood, and adult stem cells) can form several tissues.
Unipotent cells can only form one cell type.
Professional stem cells remain active stem cells continuously, e.g., Lg5+ CBCs in intestines.
Facultative stem cells are daughter cells that can dedifferentiate and become stem cells upon injury (e.g., intestinal dedifferentiation).

Classes of Stem Cells

Embryonic stem cells originate from early embryos and are pluripotent, forming many cell types.
Embryonic germ cells develop from parts of the embryo/fetus that become gametes.
Adult stem cells exist in tissues/organs after birth. They are relatively undifferentiated (multipotent or unipotent). They have limited ability to produce various cell types and self-renew. Examples include skin, bone marrow, intestine.
Cord blood stem cells are typically multipotent.
Induced pluripotent stem cells (iPSCs) arise from adult cells that are genetically altered into pluripotent cells, equivalent to embryonic stem cells.

Induced Pluripotent Stem Cells (iPSCs)

iPSCs overcome ethical considerations involved with using embryonic stem cells.
iPSCs are created by introducing stemness-related genes into adult cells.
iPSC creation involves isolating adult cells, introducing stemness genes using viral vectors, cultivating cells with inactivated feeder cells, and identifying resulting iPSCs or iES-like cells.
iPSC use requires further optimization.

Stem Cell Hierarchy and Adult Stem Cells

Stem cells become increasingly differentiated as they progress through different cell types, losing stemness.
Most adult multipotent stem cells are in a resting (quiescent) state until stimulated, then differentiate into more mature cells.
A transit stem cell differentiates when transitioned to cell cycle activity, forming a new stem cell plus a progenitor cell.
Progenitors mature.
Dedifferentiation is the reverse process; here mature cells can become less differentiated, gaining stem-like properties, reverting to an original stem cell form.

Intestinal Stem Cells

Intestine stem cells (especially CBC cell type) are proliferative, damage-sensitive, Lgr5+/AScl2+/Olfm4+ cells.
If CBC cells are lost, they can be replaced by dedifferentiating TA (transit-amplifying) cells. CBCs are actively dividing, and are likely sources of colorectal cancer.
+4 stem cells are likely quiescent, damage-resistant cells, characterized by the expression of BMI1, Hopx, and Tert. They exist as a 'reserve' tissue.

Notch Signaling and Differentiation

Notch signaling controls differentiation in the intestine, influencing the choice between absorptive or secretory lineages.
Increased Notch expression increases HES1, decreasing Atoh1, and DIl expression, promoting differentiation to absorptive lineage cells (Notch-high, Dll-low).
Decreased Notch expression increases Atoh1, which upregulates Dll expression, promoting differentiation to secretory lineage cells (Notch-low, Dll-high).

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Description

This quiz explores the definitions and characteristics of stem cells, focusing on their unique abilities such as self-renewal and differentiation. It delves into the processes of cell division, including symmetric and asymmetric division, and the concepts of cellular differentiation and dedifferentiation.