Lec 7: Molecular Pathways

What are the two main types of cell commitment mechanisms?

Autonomous (Mosaic) development and Conditional (Regulated) development.

What does specification refer to in cell differentiation?

The capacity for tissue-specific differentiation in a neutral environment.

What is determination in the context of cell commitment?

Nearly irreversible commitment to tissue-specific differentiation irrespective of the environment.

What is the primary role of transcription factors in development?

They are master regulators that interact with DNA to regulate a cascade of other genes.

What is homeosis?

The ability to transform one body part into another, such as antenna into legs.

What is the homeodomain?

A 60 amino acid DNA binding domain encoded by a 180 base pair 'homeobox'.

What is the significance of Hox genes in development?

They establish cranial-caudal segment identity and are reutilized to establish organ morphology.

What is the Hox Code hypothesis of posterior predominance?

The expression of posterior genes in a given region predominates over more anterior genes in specifying segment identity.

What are the four classes of developmental molecules?

Transcription factors, nuclear receptors, secreted factors & their cell receptors, and modifying factors

What is the role of primary cilia in development?

They facilitate signal transduction in various signaling pathways.

Name a signaling pathway involved in development.

FGF/TGFβ, WNT, SHH, or NOTCH.

What is the difference between autonomous and conditional specification?

Autonomous specification relies on determinants in the zygote, while conditional specification depends on the local environment and cell-cell interactions.

What is the DorsalixNieuwkoop Center?

A region involved in the early organization of the embryo, influencing cell fate.

What is the primitive node?

An organizing center in the early embryo that plays a key role in body plan establishment.

What is the notochord's function in development?

It serves as a structural support and signaling center during embryonic development.

What is the significance of Hox segmentation?

It is crucial for the proper organization of body segments during development.

What is a ciliopathy?

A disorder of ciliary function that can affect various signaling pathways in development.

How does conditional specification predominate in human development?

It allows for flexibility in cell fate decisions based on environmental cues and interactions.

What are the implications of transplanting uncommitted stem cells?

They may not differentiate properly, leading to less effective treatments.

What are the advantages of using determined myocardial cells for transplantation?

They are more likely to integrate and function properly in the host tissue.

What is the role of the organizing center in embryonic development?

It establishes the basic body plan and influences the differentiation of surrounding cells.

What can result from an alteration in the organizing center during development?

Abnormalities such as having an unusual number of vertebrae or duplications in body structures.

What is the role of Hox genes in segment identity?

Hox genes determine segment identity based on their expression patterns in specific segments.

What are ligand-mediated transcription factors?

Ligand-mediated transcription factors, such as estrogen and progesterone, bind to nuclear receptors to regulate gene expression.

What is Retinoic Acid (RA) and its function?

Retinoic Acid is a vitamin A derivative that regulates gene expression and activity through nuclear receptors RAR and RXR.

What is the function of CRABP in relation to Retinoic Acid?

CRABP (cellular retinoic acid binding protein) acts as a morphogen sink, regulating the levels and degradation of Retinoic Acid.

How do surface receptors mediate cellular signaling?

Surface receptors mediate signal transduction, activating transcription factors that induce or inhibit cell growth and differentiation.

What is the role of fibroblast growth factors (Fgf)?

Fibroblast growth factors promote cell growth and differentiation and have over 20 subtypes with various receptors.

What is the significance of Wnt proteins in development?

Wnt proteins are important for organizing and patterning during development and are linked to tumorigenesis.

What are structural molecules in embryology?

Structural molecules like collagens and proteoglycans provide scaffolding for connective tissue and assist in cell migration.

What is the role of enzymes in differentiated cells?

They are the custom machinery that give each type of cell its specific role and identity

What is conditional specification in human development?

Conditional specification refers to the ability of one cell or tissue to influence the fate of other cells during development.

What is the function of the primitive streak during gastrulation?

It organizes gastrulation and the formation of the three primary germ layers.

What molecular factors are involved in organizing the primitive streak?

Noggin and Cerberus, which help organize head structures.

What is the role of the notochord in embryonic development?

It acts as an axial organizer for neural tube induction and paraxial mesoderm organization.

What is the significance of SHH in development?

It is crucial for neurulation and somite formation.

What is the role of multiple enhancer elements in gene expression?

They respond to site-specific and stage-specific cues to regulate gene expression during development.

What is the impact of RA on gene regulation?

It binds to specific response elements in target genes.

What is the function of transcriptional regulation modifying molecules?

These molecules modify the transcriptional regulation of various signaling pathways, such as the Wnt pathway.

What is the significance of apoptosis in cell signaling?

It is programmed cell death mechanism that can be induced or inhibited by growth factors.

What is the role of signaling pathways in embryonic development?

Signaling pathways mediate communication between cells, influencing growth, differentiation, and morphogenesis.

How do transcription factors influence embryonic development?

When activated by signaling pathways regulate the expression of genes critical for development.

What is the importance of morphogens in development?

They are signaling molecules that dictate cell fate based on their concentration gradients.

What are the primary germ layers formed during gastrulation?

ectoderm, mesoderm, and endoderm, which give rise to all tissues and organs.

How does the environment influence embryonic development?

It can influence gene expression and developmental pathways, affecting overall embryonic development.