Patterning Embryos in 4D Flashcards
What are the three uses of animal models?
Understand biological phenomena
Distinguish between genetic and environmental contributions to a disorder
Explore causes and treatments for human diseases
How does a single-celled egg become a complex multi-cellular 3D organism?
Generating different cell types
Assigning them different shapes and functions
Patterning the embryo in 3D through time
Which process is defined as the developmental mechanisms that cause cells that are initially equal to acquire different identities?
Patterning
Which process is defined as the ability to respond to an inducing signal?
Competence
What is the process where signals from a cell alter the fate of another cell?
Induction
Pluripotent cells are (uncommitted/committed) and multipotent cells are (uncommitted/committed)
Uncommitted; committed
Identify the structure to its cell potential:
i. Blastula stage
ii. Limb bud
iii. Single cell to 8-cell morula
iv. Arm
i. Pluripotent
ii. Multipotent
iii. Totipotent
iv. Unipotent
What type of cell follows a specific pathway if left alone, can respond to other signals and whose fate is flexible?
Specified cell
What type of cell can no longer change its fate in response to new signals and whose fate is irreversible?
Determined cell
What type of cell is mature and specialized, in its final developmental stage and end of lineage?
Differentiated cell
What are the three types of specification?
Autonomous, syncytial, conditional
Which specification depends on asymmetric distribution of cytoplasmic content and cells developing according to early fate?
Autonomous
In autonomous specification, if a blastomere is removed, can it be replaced?
No it cannot, each blastomere already contains positional information
Why does a symmetrical parent cell become polarized?
Asymmetric segregation of fate determinants
What does the production of distinct daughter cells depend on in autonomous specification?
Alignment of mitotic spindle
Spindle perpendicular to determination gradient and metaphase plate parallel to determination gradient leads to (identical/unidentical) daughter cells
Identical
Spindle parallel to determination gradient and metaphase plate perpendicular to determination gradient leads to (identical/unidentical) daughter cells
Unidentical
Which specification is associated with nuclear division without cytokinesis, exposed to gradients of cytoplasmic contents?
Syncytial
Which specification depends on environmental conditions and external signals that cause the activation of different transcription factors?
Conditional
In which specification can cells compensate for missing cells?
Conditional
What experiment was done to monitor differentiation
Single cell RNA sequencing
The results of the single cell RNA sequencing experiment showed that gastrulation (epiblast cells) gave way to which cells?
Mesoderm, ectoderm, endoderm
Ectoderm differentiation gives rise to which cells?
Neural ectoderm
In an experiment where red cells from blastula become muscle cells and yellow cells from blastula become neurons, what happens when a red cell and yellow cells are mixed?
Either red cell becomes muscle and yellow cells become neurons OR red and yellow cells all become neurons
What was the process that enabled the observation of Fgf8 in the optic vesicle?
In situ hybridization
What are the steps of in situ hybridization?
Synthesize probe with Digoxigenin and RNA complementary to target mRNA
Introduce probe into the cell
Wash the cell and add anti-Digoxigenin antibody conjugated with alkaline phosphatase
Antibody attaches to RNA and causes color reaction that gives purple color
What was done to observe the role of the optic vesicle in lens induction?
Signaling molecule for Fgf8 expression was moved from the optic vesicle to the lens - Fgf8 expressed in the lens
Removal of optic vesicle - no induction of lens
What are the inductive signals of the signaling cell?
Ligands
What are the inductive signals from the receiving cell?
Receptors conduct transduction mechanism (receptor to nucleus), leading to change in gene expression and cell shape
What are the types of signaling?
Autocrine, paracrine, endocrine, juxtacrine
Retinoic acid pathway is an example of what signaling?
Endocrine
Notch-Delta signaling is an example of what signaling?
Juxtacrine
What is the concept of Notch-Delta?
Delta acts as a ligand and binds to Notch, which cleaves inside the cell
NICD turns on transcription of genes in the nucleus
What is the difference between paracrine and juxtacrine signaling?
Juxtacrine requires that the receptors of both cells are connected
Paracrine requires that the ligand from one cell moves to the receptor of another cell
Bone morphogenetic proteins, Sonic Hedgehog, Wnt and Fibroblast Growth Factor pathways are all examples of what signaling?
Paracrine
What is the mechanism of bone morphogenetic protein pathway?
Ligand forms complex with Type I and II receptors
Type II receptor phosphorylates type I receptor
Type I receptor phosphorylates R-SMAD
Phosphorylated R-SMAD forms dimer with Co-SMAD
Dimer translocates to the nucleus and activates transcription of genes
What is the mechanism of Shh pathway?
Shh binds to Ptc receptor
Smo is released from Ptc effect and is activated
Smo activates Gii transcription factors in the nucleus
What is the mechanism of Wnt pathway?
Wnt binds to receptor and stops degradation of beta-catenin
Beta-catenin translocates to the nucleus and activates gene expression
What are the kinds of ligands?
Ligands that diffuse directly into the cell
Ligands that bind to cell surface receptors
Morphogens
Estrogen, glucocorticoids and retinoic acid are what kind of ligands?
Ligands that diffuse into the cell
Shh, BMPs and bicoid are what kind of ligands?
Morphogens
FGFs and Wnt are what kind of ligands?
Ligands that bind to cell surface receptors
Morphogens are ____________ ligands that cause different responses at different distances/concentrations
Secreted
What are the three types of morphogens?
Signaling molecules, transcription factors, small diffusible molecules
Shh, BMP and activin are what type of morphogens?
Signaling molecules
Bicoid is what type of morphogen?
Transcription factor
Retinoic acid is what type of morphogen?
Small diffusible molecule
Which of the following is/are not characteristics of a morphogen?
a. Forms a concentration gradient
b. Activates target genes below concentration threshold
c. Each cell sees a different concentration
b
Which proteins help morphogens move by disassociating and reassociating with them?
HSPGs
