Flashcards in 29-30 multicellular organism developmetn Deck (57):
why do cells undergo differentiation during developmetn?
differentiation provides different tissues to perform different tasks
Stages of embryo develpment
3. interact with cells
WHat does it mean if cells have memory?
they retain signals from previous embryonic development.
What is ectoderm
sheet of epithelial cells that form the nervous system and epidermis.
The endoderm is what
forms from the ectoderm folding in, and will become the gut, lung, and liver
What is mesoderm
the layer between ectoderm and endoderm. forms the connective tissue and muscle
formation of a gut structure from a sphere of cells
what proteins class are important for development
cell adhesion, signaling proteins, gene regulatory proteins
what is a non-coding regulatory DNA?
instructions to form multicellular organism that associates with each gene
what is a non-coding sequence
sequence of DNA that will not code for anything, but makes organisms unique from one another.
why are non-coding sequences inmportatn for DNA
coding seqeunces are very similar . non-coding provides uniqueness to organism
when does a cell make a develpmental decision
before showing signs of differentiation
what does a cell do before showing signs of differentiation
developmental decision must be made
what is a determined cells
cell that is not influenced to differentiate by environmental factors
completely undetermined cells
cells undergo rapid changes due to altering environments
cells contain some form of another cell type but are still influenced by changing environment
position specific character of a cell
is positional value a memory of the cell
what is the relevance of a cells ability to maintain memory of a positional value?
allows an arm to be relocated to a thigh, and development will still continue as an arm
how can cells become different
asymmetric division, has an unequal distribution of molecules and then can directly alter patterns of gene expression among the 2 cells
where are the most important environmental signals normally from
what is inductive signaling
induction of a different developmental program in select cells of a homogenous group which changes the groups character
What are the different types of inductive signaling present?
1. short range: cell-cell contact
2. Long-range: these substances diffuses through ECM
What provides cells with memory and amplifies the weak asymmetry initiated by the environment
what provides cells with memory
what is a morphogen
long range inductive signal that imposes patterns on fields of cells based on concentration gradients
what type of gradient can morphogens form?
inducer and inhibitor. both diffuse away from the source, but inhibitor can block activity of the inducer
what is teh result of inductive events that stimulate signaling pathways
altering DNA transcription
what is signaling pathway dependent on in terms of resposne time
spatial and temporal expression of different gene sets
phases of neural development and function
1. phase 1: deifferent cell types develop independently at varying locations based on local signals
Phase 2: axons and dendrties grow along specific routes forming provisional ordered network of connections
phase 3: connections are adjusted and refined through different interactions with distant regions and electrical signals
where does the neural tube develop into
what does the neural crest cell develop into
what is the process for neural tube formation
neural groove, neural fold, neural tube as the folds meet up in midline. neural canal is the hollowed- out portion inside the tube
what provides lateral inhibtion of the neural tube
delta notch signaling
where do neural crest cells originate
from the dorsal end of the neural tube
when will neural crest cells begin theif migration
after neurlation, when the neural tube closes
what different cells types does the neural crest provide?
1. neurons/glial cells of PNS
2. catecholamine producing cells in adrenal gladn
3. skeletal and connective tissue components for the head
how do neurons migrate?
crawl along the radial glial cells that extend from the inner to outer end of the neural tube
what are the different type of neurons that develop in the spinal cord
1. dorsal: sensory
2. ventral: motor
3. intermediate: interneurons
what is teh growth cone
it uses chemotaxis to migrate through tissue. leaves a trail of axon-specific proteins to allow for axon growth, along this trail
what controls where the growth cone goes?
filopodia and lamelopodia which use monomeric GTPases Rho and Rac to control actin assembly
What do growth cones use to migrate through tissue along the proper path?
extracellular matrix environment and chemotactic factors
what specific components are used in extracellular matrix migration of the growth cones
immunoglobulin superfamily and cadherin family class receptors.
chondroitin sulfate inhibits growth.
homophilic cell adhesion molecules mediate growth cone movement via extracellular matrix mechanisms
what are teh attracting chemotactic factors for growth cone
what are the repulsive chemotactic factors for growth cone
slit and samphorin. the combination of these provides a single slot that the growth cone will migrate in between
what happens when netrin binds with its receptor?
opens the transient receptor potential C channels, which release large amounts of calcium. this activates teh movement of the growth cone, by activating filopodia
where are netrin receptors not located and what is the significance of this
not located on non-commissural neurons. prevents migration of neurons to the floor plate
where is slit secreted from
what repulsive receptor is found on commissural neurons
roundabout with binds with slit
what do neurotrophic factors have control over?
communicating and forming synapses with target cells when they reach their destination. tissue signals regulate the growth cone synapses and where
what happens to neurons that do not receive enough neurotrophic factors from the target tisseu
the neurons die via apoptosis
target cells produce the limited amount of neurotrophic factors that are required for neuron survival
what is nerve growth factor
neurotrophic factor that belongs to neurotrophins and binds with tyrosine kinase A
what is the function of nerve growth factor
promote survival of sensory and parasympathetic neurons
what are the short term effects of nerve growth factor
act on nerve growth cone and neurite extensions. cause local, rapid, and independent communication with the cell body