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139 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Morphogenesis |
“creation of shape” Maintaining shape with cell behaviors: dividing, migrating, changing their size, shape, arrangement, adhesion happens in cleavage, gastrolation, neurulation, neural crest migrationTwo |
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Two embryonic tissues involved in morphogenesis |
mesenchyme and epithelia |
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mesenchyme |
loose and unconnected cells surrounded by extracellular matrix |
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epithelium |
sheets and tubes of cells with rectangular shape and connected to each other |
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Tight junction |
seals neighboring cells together to prevent leakage |
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Gab junction |
Allows passage of small water-soluble ions and molecules between cells |
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basal lamina |
basement membrane made of protein |
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7 cell behaviors in morphogenesis |
Cell adhesion, cell shape, cell growth, cell division, cell death, cell movement (alignment, intercalation, migration), transitions between epithelium and mesenchyme |
ASGDDMT |
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Cells tend to adhere to |
their own cell type |
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What is the role of N-cadherin in neurulation? |
It is necessary to distinguish the neurula from other cells |
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What can changing cadherin expression also change? |
tissue shape |
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What is E-cadherin important for? |
Impaction |
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There is a correlation between the separation of the notochord from the rest of the mesoderm layer and the expression of what proteins? |
A specific protocadherin in paraxial mesoderm and a different protocadherin in axial mesoderm |
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How does N-cadherin allow for neural tube formation? |
It is only expressed in cells making up the neural tube |
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What is implantation? |
binding between trophoblast cell surfaces to the uterine wall involving E and P cadherins |
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What are other roles of cadherins? |
implantation and condensation |
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How does cell affinity affect the cell reorganizing process? |
the cells with stronger affinity to each other aggregate together in the center |
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Cell adhesion is controlled at the molecular level by what two proteins? |
cadherins and catenins |
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What are cadherins? |
calcium dependent adhesion proteins |
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What are the different types of cadherins? |
E, P, N, R, B, EP, and protocadherins |
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What is different about protocadherins? |
They are not anchored by catenins |
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What are catenins? |
Protein that binds to the internal part of cadherins (because they are transmembrane proteins) |
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What is strength of cell adhesion determined by? |
the number of cadherins on the surface |
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Why are cadherin expression levels consistent over time? |
helps epithelia stay together and embryos stay organized |
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What is cadherins role in normal cleavage? |
It is necessary |
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Cells tend to adhere to |
their own cell type |
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What is the role of N-cadherin in neurulation? |
It is necessary to distinguish the neurula from other cells |
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What can changing cadherin expression also change? |
tissue shape |
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What is E-cadherin important for? |
Impaction |
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There is a correlation between the separation of the notochord from the rest of the mesoderm layer and the expression of what proteins? |
A specific protocadherin in paraxial mesoderm and a different protocadherin in axial mesoderm |
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How does N-cadherin allow for neural tube formation? |
It is only expressed in cells making up the neural tube |
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What is implantation? |
binding between trophoblast cell surfaces to the uterine wall involving E and P cadherins |
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What are other roles of cadherins? |
implantation and condensation |
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Microtubules |
located central cytoplasm. |
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Microfilaments |
located in the cortical cytoplasm. They are responsible for apical constriction, cleavage furrow formation in cytokinesis, formation of acrosomal process in sperm and fertilization cone in egg, formation of temporary structures for cell locomotion and cell intercalation. |
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How does cell affinity affect the cell reorganizing process? |
the cells with stronger affinity to each other aggregate together in the center |
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Cell adhesion is controlled at the molecular level by what two proteins? |
cadherins and catenins |
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What are cadherins? |
calcium dependent adhesion proteins |
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What are the different types of cadherins? |
E, P, N, R, B, EP, and protocadherins |
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What is different about protocadherins? |
They are not anchored by catenins |
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What are catenins? |
Protein that binds to the internal part of cadherins (because they are transmembrane proteins) |
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What is strength of cell adhesion determined by? |
the number of cadherins on the surface |
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Microtubules |
located central cytoplasm. Responsible for transporting organelles, chromosomes, vesicles, and granules inside the cell. Form specialized permanent structures for cell and fluid movement. Cell elongation and shape |
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What is cadherins role in normal cleavage? |
It is necessary |
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Microtubules are assembled from |
tubulin dimers |
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lamellipodia |
sheet like (palm of hand) for cell intercalation, alignment, and cell migration |
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pseudopodia |
(foot like) for migration through tissues |
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what is an example of cells using filopodia in development? |
Frog gastrulation. The cells use the filopodia to migrate along the roof of the blastocoel. Mouse neurulation. neural fold closure |
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What protein is essential for gastrulation? |
Fibronectin |
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Neuronal growth cones form from which two structural forms? |
filopodia and lamellopodia |
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What are the two main mechanisms for specifying cell fate? |
Autonomous specification and conditional specification |
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What are the two phases of differential gene expression? |
Cell specification (a cell learning its fate) cell differentiation (a cell becoming its type) |
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What controls differential gene expression? |
Morphogenetic factors/determinants |
basically TFs |
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autonomous specification |
determinants present in the parent cell that get passed onto the daughter cells unequally |
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conditional specification |
signals from outside the cell |
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Microfilaments are assembled from |
globular actin |
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mosaic development |
Autonomous specification most important usually invertebrate embryos plan in egg theory |
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regulative development |
mostly vertebrate embryos epigenesis theory |
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induction |
cell signaling between tissues |
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3 kinds of cell signals are |
Paracrine, juxtacrine, and autocrine |
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paracrine signaling |
signal is secreted locally to diffuse around in a gradient |
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juxtacrine |
signal between cells using cell to cell contact |
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autocrine signaling |
secreted and diffuses to the same population of cells. hormones? |
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What are the four important families of diffusing paracrine factors? |
1. fibroblast growth factor 2. hedgehog family 3. wingless or wnt family 4. transforming growth factor beta superfamily |
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Competent tissue |
A tissue that expresses a receptor protein for that signaling protein |
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signal transduction pathway (STP) |
Mechanism where ligand causes an effect in the nucleus |
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What is the orientation of cleavage planes controlled by? |
the position of the centrosome and sperm entry |
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The two types of transcription factors we talk about are |
Constitutive (general/basal) Developmental |
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Constitutive (general/basal) transcription factors |
expressed and active in all cells and for all genes do not affect cell fate do not function in differential gene expression |
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Developmental transcription factors |
expressed only in certain cells and stages affect cell fate turned on or activated by determinants acquired from parent cell or cell signaling function in differential gene expression |
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2 roles of developmental transcription factors: |
Bind to enhancer or silencer regions of genes |
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Two things about transcription factors: |
Many different tfs bind to one enhancer. A particular concentration needed to activate. Multiple enhancers exist for each gene |
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The frog egg has one axis which is |
animal-vegetal |
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The frog egg axis has what type of symmetry? |
radial |
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What is the first event in development that could potentially begin to specify the body plan? |
sperm entry |
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Cortical rotation |
movement of cell cortex and cell membrane toward the point of sperm entry |
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When does cortical rotation take place? |
Before the first cell division |
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Cell alignment, intercalation, and migration involve what proteins |
ECM proteins and integrins |
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How does cortical rotation take place? |
Microtubules extend from the sperm centriole in parallel tracts and pull cortex and cell membrane towards sperm centriole |
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Where do the microtubules originate during cortical rotation? |
mother cell |
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how does cortical rotation affect later development? |
gastrulation is inhibited |
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defect experiment |
kill or remove part of the embryo |
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isolation experiment |
separate parts of the embryo |
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recombination experiment |
recombine two parts of the embryo that are not normally together |
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transplantation experiment |
replace part of one embryo with the same part of another embryo but from a different orientation or stage. |
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what structural feature needs to be present to allow gastrulation? |
the gray crescent |
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how could one rescue an embryo that doesn’t contain a gray crescent? |
transplant a dorsal vegetal cell from another embryo into it |
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What happens if you add another gray crescent to a normal embryo? |
gastrulation happens twice causing two heads |
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What are some examples of ECM proteins? |
different collagen types, fibronectin, and laminin |
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cortical rotation causes |
dorsal vegetal side to become signaling center (Nieuwkoop Center) |
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What does the Nieuwkoop Center do? |
Induces the dorsal lip to form |
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When and how are the three germ layers specified? |
Late blastula phase endoderm induces mesoderm to become specified |
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What is the Spemann Mangold organizer (SMO)? |
a second signaling center in the endoderm which induces the mesoderm to be specified |
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What does the SMO become? |
the dorsal lip of the blastopore which induces adjacent tissues |
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When they transplant the SMO into a different embryo and location, what happens? |
invagination occurs in that area as well |
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What axial differentiation does the SMO induce? |
Anterior posterior |
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Where are autonomous factors first expressed? |
in separate ends of the egg maternal factors |
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Which pole are the maternal factors located? |
vegetal pole |
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What are the maternal factors expressed in the vegetale pole? |
VegT, Vg1 |
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Which protein makes up the basal lamina? |
laminin and type IV collagen |
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What is the timeline of the maternal factors? |
transcription begins at fertilization, end up in vegetal cells (NC), allows for mesoderm derivatives |
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What is B-catenin? |
a multifunctional protein: anchor for catenins and a transcription factor accumulates in cells on dorsal side of embryo Makes NC |
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What protein degrades B-catenin? |
GSK-3 |
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What happens to Dsh protein after cortical rotation? |
Gets actively transported to dorsal side |
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What proteins do Dsh block? |
GSK-3 |
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When does goosecoid turn on? |
When there are high concentration signals from the NC. Causes SMO to form |
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What tf is expressed in low concentrations of B-catenin? |
Xbra. It turns on other mesoderm-specific genes (BMP and wnt) |
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what are fibronectin and laminin involved with? |
cell adhesion and cell shape |
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integrins link which two proteins |
ECM proteins with actin of the cytoskeleton |
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Fibronectin causes the cell membrane to do one of three things. list all three |
Filopodia lamellipodia pseudopodia |
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filopodia |
spine-like (finger like) for cell crawling |
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Increasing TGF-B concentration does what? |
specify more dorsal mesoderm derivatives |
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How does organizer mesoderm induce ectoderm in the head? |
Secretes antagonist proteins for both BMP and Wnt signaling proteins: Cerberus, Frzb, and Dickkopf |
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What proteins are secreted by trunk organizer mesoderm? What do they do? |
noggin, chordin, follistatin Bind to Wnt and BMP (secreted by non organizer mesoderm) Turns head ectoderm into other derivatives (brain, eyes) |
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Sclerotome |
The part of the somite giving rise to bone or other skeletal tissue |
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What does hairy tf do? |
expressed in anterior part if somite allowing for borders to form |
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How would you describe the expression levels of hox genes throughout the spinal chord? |
Nesting with staggered anterior borders |
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When are hox genes first expresses? |
In unsegmented presomitic cells while they are in the epiblast. 3’ ends come on first and anteriorly |
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When do the hox genes turn off expression? |
after the somites break up |
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What is the related orientation between hox genes and segmental expression? |
Hox genes are related to segmental expression because the 3’ end of the genes express more anterior characteristics |
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What are orthilogs? |
the same gene in different species |
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What are paralogs? |
The same gene within a species but replicated a bunch (chromosomes) |
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What is a master regulatory gene? |
A gene that codes for a transcription factor that starts a cascade of proteins which end up completely differentiating into their final organ. (becoming an eye) |
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What is a homeodomain? |
The part of the protein that binds to DNA |
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What is a homeobox? |
A region of DNA that codes for the DNA binding part of the protein (homeodomain) |
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What does paraxial mesoderm become? |
Somites -> muscles of the body wall and back, ribs and vertebrae, strips of back dermis, and limb muscles |
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How do somite borders form? |
Uses ephrine (posterior) to juxtacrine signal and bind to Eph receptor (Anterior) |
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What does intermediate mesoderm become? |
Kidney and genital ducts |
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What does lateral plate mesoderm become? |
heart, blood vessels, blood cells, linings of coelom, limb skeleton |
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What are the cell types specified after somites? What are they responsible for? |
Sclerotome (cartilage), Dermatome(dermis, skeletal muscle), Myotome (skeletal muscle), Syndetome (tendons), and Endothelial cells (dorsal aorta) |
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Space, timing, and direction of segmentation is specified how? |
Intrinsically or autonomously in the presomitic mesoderm |
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What ECM proteins do somites express? what do they do? |
N-cadherin (keeps the cells of each somite together) and fibronectin (separates the somites) |
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How do somites break up? |
convert epithelium to mesenchyme (loose N-cadherin expression and loose adhesion) |
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What controls the staggered anterior borders of hox gene expression? |
Wnt, FGF, RA gradients |
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What protein binds to enhancers of hox genes? |
RA |
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Do different hox genes specify different types of vertebrae across different species? |
yes |
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When a hox gene is knocked out, that area expressed what region instead? |
The more anterior region |
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What is a homeotic transformation? |
Conversion of one body part into another. Happened during hox gene knockouts |
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Posterior hox genes are more dominant or recessive? |
Dominant |
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