Stem Cells and Cell Behavior Quiz

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Questions and Answers

What is defined as the developmental history of a cell from its birth until its final division and differentiation into a specific cell type?

Cell lineage (correct)

Cell apoptosis

Cell differentiation

Cell morphology

Which type of stem cells can give rise to any cell type in the body, including placental cells?

Progenitor cells

Pluripotent stem cells

Totipotent stem cells (correct)

Multipotent stem cells

Which of the following correctly describes apoptosis?

A form of uncontrolled cell growth

A random cell death without a specific trigger

A programmed cell death process (correct)

An irreversible phase of necrosis

Which of these terms describes stem cells that are derived from adult tissues?

Adult stem cells Signup and view all the answers

What initiates the apoptosis process within a cell?

Activation of caspases Signup and view all the answers

In the context of stem cells, what does 'self-renewing' refer to?

The ability to produce exact copies of themselves Signup and view all the answers

Which type of cell division allows stem cells to produce two identical stem cells?

Symmetric division Signup and view all the answers

Which family of proteins is primarily involved in regulating apoptosis?

Bcl-2 family Signup and view all the answers

What type of cells do Lgr5+ cells differentiate into when Notch signaling is inactive?

Secretory cells Signup and view all the answers

What is the primary function of Paneth cells in the intestinal niche?

Secreting antimicrobial defense proteins Signup and view all the answers

Which of the following cell types is responsible for restoring Lgr5+ stem cells after injury?

Reserve stem cells Signup and view all the answers

What is the main role of induced pluripotent stem (iPS) cells?

To serve as a model for understanding disease Signup and view all the answers

What defines multipotent cells in terms of their differentiation capability?

They can develop into more than one cell type but not all. Signup and view all the answers

Which type of cell specializes in producing and releasing hormones in response to stimuli?

Enteroendocrine cells Signup and view all the answers

What differentiates fetal stem cells from adult stem cells?

Fetal stem cells are taken from fetuses and have more differentiation potential. Signup and view all the answers

How do transiently amplifying cells differ from other stem cells?

They divide rapidly but have limited self-renewal capacity. Signup and view all the answers

What significant feature distinguishes telocytes from other cell types in the intestines?

Their long protrusions forming a network Signup and view all the answers

At which stage of embryonic development do totipotent cells exist?

At the 8-cell stage. Signup and view all the answers

What role do intestinal stem cells play in the intestinal epithelium?

They replace cells in the intestinal epithelium that are lost daily. Signup and view all the answers

What specialized function do goblet cells perform in the intestinal epithelium?

Secreting mucus Signup and view all the answers

Which of the following best describes the nature of symmetric cell division?

Division yielding two identical daughter cells Signup and view all the answers

What is a key feature of the intestinal niche for stem cells?

It maintains undifferentiated stem cells while blocking excess proliferation. Signup and view all the answers

What is the primary characteristic of embryonic stem cells (ES cells)?

They can generate all embryonic tissues but not extraembryonic tissues. Signup and view all the answers

Which components are crucial for maintaining the pluripotency of embryonic stem cells?

DNA methylation and transcription factors. Signup and view all the answers

Which receptor is specifically expressed by Lgr5+ intestinal stem cells?

Lgr5 Signup and view all the answers

Which type of stem cells are defined as multipotent?

Adult stem cells. Signup and view all the answers

How often does the intestinal epithelium turnover in adult mammals?

Every 5 days Signup and view all the answers

What distinguishes induced pluripotent stem cells (iPS) from other stem cell types?

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

Which signaling pathway is involved in maintaining intestinal stem cell populations?

Wnt pathway Signup and view all the answers

Where are intestinal stem cells located within the intestinal structure?

At the bottom of intestinal crypts Signup and view all the answers

How long can embryonic stem cells be cultured while maintaining their properties?

Indefinitely in specified conditions. Signup and view all the answers

What is the defining characteristic of pluripotent cells as compared to totipotent cells?

Pluripotent cells can only give rise to certain lineages unlike totipotent cells. Signup and view all the answers

What is necessary for asymmetric cell division to occur?

The parental cell must become polarized. Signup and view all the answers

Which step is NOT part of generating polarized cells?

The cytoskeleton must remain unchanged. Signup and view all the answers

What role do cell polarity determinants play in asymmetric cell division?

They are localized asymmetrically within the cell. Signup and view all the answers

What factor is essential for vertebrate cells to avoid apoptosis?

Trophic factors or survival signals. Signup and view all the answers

Which component is NOT included in conserved apoptotic pathways?

Ribosomal RNA. Signup and view all the answers

What happens if the mitotic spindle is not properly oriented during cell division?

Determinants may not segregate properly. Signup and view all the answers

Which of the following is NOT a necessary process for establishing cell polarity?

Equal distribution of components. Signup and view all the answers

What is a key feature of the intrinsic program that generates cell polarity?

It uses feedback loops. Signup and view all the answers

Which protein forms channels in the outer mitochondrial membrane, promoting apoptosis?

Bax Signup and view all the answers

What is the role of Bcl-2 in the regulation of apoptosis?

It inhibits the activation of caspases by blocking Bad. Signup and view all the answers

Which factor directly activates the caspases leading to apoptosis?

Cytochrome c Signup and view all the answers

What process differentiates apoptotic cells from necrotic cells?

Apoptotic cells condense and fragment. Signup and view all the answers

Which protein is induced by DNA damage to promote apoptosis?

Puma Signup and view all the answers

What is the function of BH3-only proteins in apoptosis?

They activate the apoptosis signal by binding to Bcl-2. Signup and view all the answers

What is the role of 14-3-3 protein in apoptosis related to Bad?

It sequesters phosphorylated Bad to prevent apoptosis. Signup and view all the answers

What occurs when trophic factors bind to their receptors in the context of apoptosis?

They initiate a phosphorylation relay that sequesters Bad. Signup and view all the answers

Study Notes

Stem Cells, Cell Asymmetry, and Cell Death

Learning Objectives: Define apoptosis, apoptosome, asymmetric/symmetric cell division, Bcl-2 family, caspases, cell fate, cell lineage, embryonic stem cells, iPS cells, multipotent/pluripotent, progenitor cells, stem cell, stem-cell niche survival signals and totipotent. Differentiate stem cell categories used in research/therapy. Discuss key stem cells in the intestinal stem cell niche. Compare apoptosis and necrosis.
Cell Lineage: Developmental history of a cell from its birth until its final division and differentiation is known as its cell fate. A cell lineage traces the order cells develop as they progressively become more restricted in their developmental potential. For example, the nematode worm C. elegans has a defined lineage for all its cells.
Stem Cells: Unspecialized cells that can reproduce themselves and generate specific types of more specialized cells. There are four main types:
Adult stem cells: Derived from adult tissues.
Fetal stem cells: Derived from fetuses, more powerful differentiating potential than adult stem cells.
Embryonic stem cells: Taken from blastocysts (4-5 days post-fertilization), high differentiation potential.
Induced pluripotent stem cells (iPS): Adult cells reprogrammed to gain stem cell capabilities.
Totipotent cells: Human embryos at the 8-cell stage can form any tissue (embryonic and extra-embryonic). At the 16-cell stage, cells are committed and are no longer totipotent.
ES cells (Embryonic Stem cells): Cells from inner cell mass of blastocysts, can generate all embryonic tissues, but not extra-embryonic tissues (e.g., placenta). These are pluripotent. Pluripotent cells can generate any cell type in the body.
Pluripotency Control (ES cells): Controlled by multiple factors: DNA methylation, chromatin regulators, miRNAs, transcription factors like Oct4, Sox2 and Nanog.
Adult Stem Cells: Critical for replacing cells with shorter lifespans (stomach lining, some immune cells). Multipotent (except germline stem cells, which are unipotent). Multipotent cells can develop into more than one cell type, but are more limited than pluripotent cells (cannot generate all cell types). Number of stem cells (either stable or increasing) during the organism's lifetime. Hematopoietic stem cells replenish all necessary blood cells.

Cell Polarity and Asymmetric Cell Division

Symmetric cell divisions: Daughter cells are identical to parent cells (e.g., yeasts, fungi, some eukaryotes, hepatocytes).
Asymmetric cell divisions: Daughter cells inherit different components (mRNA, proteins) despite the same genes. They can differ in size, shape, protein composition; or states of gene activity/potential activity. Asymmetric cell division requires a polarized parental cell (uneven distribution of cell contents). Cells have an intrinsic program to create polarity via feedback loops.

Polarized Cells

Generating polarized cells:
1. Cells exposed to a spatial clue.
2. Receptors sense the clue.
3. Signal transduction initiates.
4. Cytoskeletal reorganization (e.g., microtubules and/or microfilaments to reorganize in the appropriated polarized manner).
5. Polarized cytoskeleton guides transport of polarity determinants.
6. Cell polarity determinants reinforce polarity. These include mRNAs, proteins, and lipids, asymmetrically localized in a cell.

Cell Death

Vertebrate cells, apoptosis: Cells require survival signals (trophic factors). In their absence, cells induce programmed cell death (apoptosis). Apoptotic pathways involve membrane-bound regulatory proteins, cytosolic regulatory proteins, and apoptotic proteases (caspases). Caspases cleave intracellular substrates, causing cell demise.
Components of Apoptosis: Apoptotic proteins (e.g., CED-4, Apaf-1), which bind cytoplasmic regulatory proteins and caspases, are essential for caspase activation.
Necrosis vs. Apoptosis: Apoptosis involves shrinking, condensation, fragmentation into apoptotic bodies ingested by phagocytic cells. Necrosis involves cell swelling, bursting, and releasing intracellular content; it can induce inflammation.

Bcl-2 Family

Bcl-2 family: Contains pro- and anti-apoptotic proteins, many are transmembrane proteins.
Pro-apoptotic: Bax, Bak, Bok.
Pro-survival: Bcl-2, Bcl-xL, Bcl-w, Mcl-1, A1
Interactions between these proteins determine cell fate.
Factors affecting pro-apoptotic proteins include trophic factor binding (or lack thereof), DNA damage and removal from substratum.

Fas-Mediated Apoptosis

Triggered by extracellular death signals (e.g., tumor necrosis factor and Fas ligand).
Receptors oligomerize associated proteins (e.g., FADD), leading to caspase cascade triggering apoptosis.

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Description

Test your knowledge on stem cells, cell asymmetry, and the processes of apoptosis. This quiz covers key concepts in cell division, differentiation, and the distinctions between various types of stem cells. Dive deeper into the important roles of stem cells in research and therapy.