Cell Biology and Development Quiz

Apoptosis, or programmed cell death, is crucial for shaping tissues and organs through cell removal.

Two types of apoptotic cells (C-type and D-type) exist, with distinct characteristics and timed roles in nervous system (neural tube) development The C-type cells shrink quickly, whereas the D-type cells remain round and migrate.

Apoptosis removes specific cell populations and aids in the precise closure of the neural tube during embryonic development.

Apoptosis removes cells that produce FGF8. This removal controls FGF8 levels and inhibits excessive proliferation.

Apoptosis helps create folds and shapes in tissues like limbs and during the development of animals.

P granules are cytoplasmic structures that separate from the cytoplasm, enabling their movement to specific locations in a cell, often related to segregation during cell division, particularly in germ line development.

Cell division in C. elegans where one daughter cell receives different signals than the other, leading to distinct fates and cell types.

In C. elegans embryonic development, the Notch signaling pathway determines cell fate through cell-cell contact, where ligands of the Notch pathway can only signal one daughter cell, not both. This process can lead from a symmetrical division to an asymmetric outcome for the cells.

A stage in Drosophila development where numerous nuclei are present within a common cytoplasm, prior to individual cell formation.

Genes whose products are provided by the mother, determining early development in an embryo.

A deficiency in S6 kinase, a protein that controls ribosomal protein synthesis. This leads to smaller organs and slower development, without affecting the overall number of cells.

FOXO, a signaling protein, regulates organ size by controlling the number of cells. Higher FOXO expression leads to fewer cells and smaller organs; reduced FOXO expression would lead to larger organs

Growth (increasing cell size) and proliferation (increasing cell number) are controlled separately, regulated by different pathways.

Myc is a protein that controls organ size by influencing cell competition. Overexpression of Myc in cells leads to faster growth, potentially causing them to displace neighboring cells.

Overexpression of S6K leads to larger cells, and an uneven wing growth (one layer overgrown over the other), particularly in the wing.

A process during embryonic development where cells migrate towards the center of the body, leading to elongation of the body axis.

The planar cell polarity (PCP) pathway controls convergent extension by regulating cell shape changes and movement.

A technique using tissue from a frog embryo to study convergent extension in isolation.

An embryo lacking the Wnt5a gene shows severe defects in body structure outgrowth, highlighting the crucial role of Wnt5a in morphogenesis.

Convergent extension is essential for proper neural tube closure. If CE is impaired, it can lead to birth defects like exocephaly and spina bifida.

A process where epithelial cells transform into mesenchymal cells, characterized by changes in cell shape, polarity, adhesion, and migratory potential. It's crucial for embryonic development and tissue formation.

Epithelial cells are characterized by their polygonal or columnar shape, apico-basolateral polarization, strong cell-cell interaction through adherens junctions, and limited migration potential. They express markers like E-cadherin, cytokeratins, occludin, and claudin.

The reverse process of EMT, where mesenchymal cells transform back into epithelial cells. This is essential for wound healing and organ regeneration.

Mesenchymal cells have spindle shapes, anterior-posterior polarization, focal cell-cell interaction, high migratory potential due to paracrine signaling, and express markers like N-cadherin, vimentin, fibronectin, Snail, and Slug.

Epithelium refers to a tissue that lines surfaces and cavities. Previously, it was thought that these cells were permanently differentiated and static in their function. However, we now understand that they can activate EMT and change their phenotype.

A process where one cell type transitions into another, usually through EMT or MET. This allows cells in terminally differentiated epithelium to change their fate and become mesenchymal derivatives.

EMT plays a key role in embryonic development by facilitating the formation of new tissues. It enables epithelial cells to migrate and differentiate into mesenchymal cells, which contribute to the formation of organs and structures.

EMT plays a role in cancer metastasis. Cancer cells can undergo EMT, gain migratory and invasive properties, and spread to distant sites.

The extracellular matrix (ECM) acts like a storage space for signaling molecules, creating a concentration gradient of morphogens and growth factors. This gradient is formed not only by production and degradation, but also by the binding of these molecules to the ECM itself.

ECM components can act as co-receptors, embedded in cell membranes, allowing for signaling within close proximity to the cell. This type of signaling is called juxtacellular signaling.

Proteoglycans are large molecules found in the ECM. They consist of a central protein core with covalently attached sugar chains called polysaccharides. Each proteoglycan can bind to different amounts of carbohydrates, giving it specific binding sites for other molecules.

Proteoglycans play a key role in paracrine signaling by acting as a reservoir for growth factors, preventing them from triggering cellular pathways prematurely.

Heparan Sulfate (HS) is a linear polysaccharide that binds to proteins, forming proteoglycans. HS is essential for ligands to bind to their receptors effectively. Without HS, many binding processes would not occur.

Mutations that block the synthesis of Heparan Sulfate can cause developmental defects in cell migration, morphogenesis, and differentiation. These mutations often resemble defects in signaling pathways because HS is involved in their function.

Fibroblast Growth Factor 1 (FGF1) is essential for gastrulation. Mutations that block HS synthesis have the same phenotype as mutations in the FGF1 gene, highlighting the importance of HS for signaling pathways.

Heparan Sulfate (HS) proteoglycans can exist in two forms: loose and membrane-bound. Loose HS proteoglycans, like agrin and perlecan, are not associated with membranes. Membrane-bound HS proteoglycans, like glypians and syndecans, are attached to cell membranes and act as co-receptors or mediate paracrine signaling.

Cytoplasmic structures found in C. elegans that separate from the cytoplasm, allowing them to be moved to specific locations within the cell. They are often involved in the distribution of mRNA and proteins during cell division, particularly affecting germ line development.

A type of cell division where the resulting daughter cells inherit different components, leading to distinct fates and eventually different cell types. This is crucial for generating cell diversity during development.

A cell-cell communication pathway that plays a key role in asymmetric cell division in C. elegans. It involves ligand-receptor interactions between neighboring cells, influencing the fate of the receiving cell.

Genes that control the identity of body segments during development. They specify which structures should form in specific regions, ensuring proper body plan formation.

A developmental stage in Drosophila where the syncytial blastoderm transitions into a cellular blastoderm, where individual cells with their own membranes are formed.

Two key processes in embryonic development. Gastrulation involves the inward folding of cells, forming the germ layers that give rise to different tissues and organs. Segmentation involves the division of the body into repeated segments, laying the foundation for body plan organization.

Organ branching can be either 'stereotypical' (genetically controlled pattern) or 'stochastic' (no pre-determined pattern).

Budding creates new branches from existing ones de novo, while clefting divides existing branches into 2-3 new tips.

Both creating new branches (budding or clefting) and reorganizing existing ones contribute to branching morphogenesis.

Invasive collective cell migration occurs in Drosophila trachea and blood vessels, with leader cells migrating forward and following cells forming a stem.

Leader cell identity in Drosophila trachea and blood vessels is determined by RTK signaling, with FGF in trachea and VEGF in blood vessels.

Delta/Notch signaling is used in trachea and blood vessels for lateral inhibition, preventing subsidiary cells from becoming leaders.

In Drosophila trachea, FGF/Bni signaling is essential for leading cells at the branch tip.

Invasive collective cell migration involves coordinated cell movement, proliferation, and deformation, with the cytoskeleton playing a key role. It's crucial for building branches.

The Jap complex in Drosophila is an inhibitor of apoptosis proteins. It needs to be deactivated for apoptosis to occur.

The antagonists Hid, Reaper, and Grim trigger apoptosis by causing the degradation of Diap 1, a protein that inhibits apoptosis.

Dronco is an initiator caspase that interacts with effector caspases like Ice and Dcp1, activating the apoptotic cascade.

P35 is a specific inhibitor of execution caspases, preventing apoptosis.

Apoptosis-induced proliferation (AIP) is a process where apoptotic cells can trigger the proliferation of neighboring cells.

Junk signaling promotes the secretion of factors that can induce AIP or AIA (apoptosis induces apoptosis).

P53 is activated via Dronc and Arc in Drosophila, triggering Junk signaling and cell hyperplasia.

Imaginary discs are regions in Drosophila larvae that will eventually develop into adult structures like wings and eyes.

Heparan sulfate proteoglycans (HSPGs) are large molecules in the extracellular matrix that play a crucial role in cell signaling and developmental processes. They bind to signaling molecules (morphogens) and regulate their activity.

Dally and Dlp are two types of HSPGs found in Drosophila. They are involved in the movement of Hedgehog (Hh) signaling molecules, playing a crucial role in wing development.

Lipid-mediated transport involves the attachment of signaling molecules to lipids, forming a complex that allows efficient transport. These complexes are often packaged within lipoprotein particles, which travel through the extracellular environment.

Lipoprotein particles are vesicles that carry lipids and associated proteins. They are important for transporting signaling molecules like Hedgehog and Wnt, ensuring their efficient delivery to target cells.

LDL receptors are proteins on cell surfaces that bind to lipoprotein particles. They play a crucial role in receiving signaling molecules and initiating intracellular signaling pathways.

LRP6 is a specific LDL receptor involved in Wnt signaling. It is essential for developing the forelegs and pelvic limbs.

Sog and Dpp are soluble factors that influence the activity of signaling molecules. These factors can increase or decrease signaling by interacting with the morphogens directly.

Signaling molecules can bind to soluble partners, which are proteins or other small molecules that exist freely in the extracellular environment. These interactions can modify the signaling molecule's activity or target its delivery.

A model explaining morphogen movement in the extracellular space, often using the analogy of a drunk sailor randomly moving away from a ship (the cell) with a random number of steps.

A simple model where morphogens move randomly away from the source, leading to a gradual decrease in concentration over time.

A more complex model where morphogens encounter various attractants and regulators, influencing their movement.

The ECM acts as a reservoir for morphogens and growth factors, influencing their concentration gradient and movement.

Signaling that occurs within close proximity to the cell, often involving ECM components as co-receptors.

The complex process by which a multicellular organism forms. It involves structural and functional cell reorganization, creating complex 3D structures through precise coordination of cell group interactions in time and space.

Morphogenesis involves three main processes: 1) reorganization of cell shape and movement, 2) cell group interactions, and 3) spatio-temporal precision, meaning that the processes occur in a specific order and location.

Developmental biology encompasses a variety of processes, including prenatal and postnatal development, growth, differentiation, metamorphosis, tissue repair, regeneration, and evolutionary developmental biology (EVO/DEVO).

Apoptosis, programmed cell death, is crucial for sculpturing tissues and organs by removing specific cells. This process ensures proper formation of structures and eliminates unwanted cells.

EMT enables epithelial cells, typically structured and immobile, to transform into mesenchymal cells, which are migratory and contribute to tissue formation. This process is vital for development and wound healing.

The ECM acts as a scaffold for cells, providing structural support and holding signaling molecules like morphogens, which can activate developmental pathways.

HSPGs are abundant molecules in the ECM that bind to signaling molecules, including morphogens, influencing their activity and regulating cell signaling.

Budding creates new branches de novo, while clefting divides existing branches into multiple new tips.

Programmed cell death in Drosophila is crucial for shaping tissues and organs, particularly during dorsal closure of the embryo, where it removes the amnioserosa and influences its migration.

In vertebrates, apoptosis is crucial for the closure of the neural tube during embryonic development. It removes specific cells, promoting the fusion of the neural folds and the formation of dorsal structures in the nervous system.

In Drosophila, apoptosis plays a significant role in the development of male gonads, allowing them to rotate 360 degrees through the elimination of specific cells.

Dorsal closure is an active process where the lateral ectoderm folds upward to close the embryo's dorsal surface. Apoptosis of the amnioserosa, an extraembryonic tissue, is essential for this process by causing cell shrinkage, migration, and removal, contributing to closure.

Inhibiting apoptosis in Drosophila embryos leads to a delay in dorsal closure, indicating the essential role of programmed cell death in the accurate and timely closure of the dorsal end of the embryo.

During dorsal closure in Drosophila, apoptotic cells undergo apical constriction, a process where the cell's upper part narrows, while the lower part thickens, leading to gradual constriction. This change in cell shape is crucial for the movement and removal of cells during apoptosis.

A gradient of signaling molecules, known as morphogens, is established across a tissue. The concentration of these molecules determines the fate of cells in different regions.

A signaling molecule that creates a concentration gradient across a tissue, providing positional information to cells.

The formation of a cavity or hollow space within a tissue, often through cell death or fluid accumulation.

A mechanism that creates repeating patterns in an organism, often used for segmenting the body. The clock is controlled by cyclical gene expression.

Programmed cell death that plays a crucial role in shaping organs and tissues by removing unwanted cells.

Large molecules found in the extracellular matrix (ECM) that bind to signaling molecules (morphogens) and regulate their activity.

The part of a somite that develops into the vertebrae and ribs.

The part of a somite that develops into skeletal muscles.

The part of a somite that develops into the dermis (skin) and muscles.

Process where mesenchymal cells transform into epithelial cells.

A somite is a block of mesoderm that forms during embryonic development. It is formed by MET (Mesenchymal-Epithelial Transition), allowing mesenchymal cells to transform into epithelial cells.

The Mesp gene controls the MET process, driving the formation of epithelial blocks from mesenchymal cells. It is expressed in the epithelial part of the somite and promotes the expression of Ephrin-E4 and Ephrin-B2, crucial for establishing new somites and lengthening the body.

EMT is a process where epithelial cells, typically structured and immobile, transform into mesenchymal cells, which are migratory and can move around. This is crucial for embryonic development and tissue formation.

Cancer cells can undergo EMT, gaining migratory and invasive properties. This enables them to spread to distant sites in the body, forming metastases.

Branching pattern strictly controlled by genes. Examples: Mammalian lungs, Drosophila tracheas, and kidneys.

Branching without a fixed pattern. No spatial limits. Examples: Mammary and salivary glands, blood vessels.

Creating new branches from existing ones. New branches are formed de novo (from scratch).

Dividing existing branches into 2-3 new tips by forming grooves.

Leader cells migrate forward while other cells rearrange behind them, forming a stem. This happens in Drosophila tracheas and blood vessels.