cell differentiation

What is cell differentiation?

The process by which unspecialized stem cells become specialized cells with distinct functions.

What is the difference between totipotent and pluripotent cells?

Totipotent cells (e.g., zygote) can become any cell type, including extraembryonic tissues; pluripotent cells (e.g., embryonic stem cells) can become any body cell but not extraembryonic tissues.

What are the 3 primary germ layers formed during development?

Ectoderm, Mesoderm, and Endoderm.

What is the end result of repeated cycles of gene silencing and activation during development?

The formation of specialized cells and tissues with progressively narrowed potential fates.

What is the role of polycomb group proteins during differentiation?

They silence genes during development.

What is the role of trithorax group proteins during differentiation?

They maintain gene expression.

What does the ectoderm give rise to?

Brain, nerves, outer epithelium (skin, hair, mammary glands).

What does the mesoderm give rise to?

Muscle, skeleton, kidneys, gonads, blood, connective tissue.

What does the endoderm give rise to?

Gut, liver, pancreas, thyroid, parathyroid, thymus.

What happens to potential cell fates during development?

They narrow as cells differentiate.

What are the two major cell types formed during gastrulation?

Epithelial and Mesenchymal cells.

What are key characteristics of epithelial cells?

Tight junctions, sheet-like arrangement, apical-basal polarity, high cell-to-cell adhesion (via cadherins).

What are key characteristics of mesenchymal cells?

Loose structure, little polarity, high matrix adhesion (via integrins), found in connective tissues.

What is EMT and MET?

EMT: Epithelial-Mesenchymal Transition.

MET: Mesenchymal-Epithelial Transition.
These processes allow inter-conversion during development.

What proteins mediate cell-cell adhesion in epithelial cells?

Cadherins

What proteins mediate cell-to-ECM adhesion in mesenchymal cells?

Integrins

What are the intracellular signaling proteins involved in cadherin and integrin adhesion?

β-catenin (cadherins), focal adhesion kinase or FAK (integrins).

What factors regulate cell differentiation?

1. Epigenetic state
2. Cell adhesion (neighborhood)
3. Growth factor signaling
4. Microenvironment (O₂, nutrients, stress)

What is gastrulation?

A key developmental process where mesoderm forms and body axes are established.

What structure forms to organize the body axis?

The primitive streak (establishes anterior/posterior and dorsal/ventral axes).

What does the interaction between ectoderm and endoderm produce?

Mesoderm and mesodermal progenitor cells.

What is the role of concentration gradients of growth factors?

They help pattern tissues by activating different gene expression pathways depending on signal strength.

What are satellite cells?

Muscle stem cells that can regenerate muscle tissue.

What does it mean that stem cells in adult tissues are multipotent?

They can become a few related cell types but not all types.