Biochemistry - Control of Development Flashcards
What is control of development…
It is where sets of genes are differentially regulated and expressed resulting in different types of cells.
What does gene control depend on?
Transcription factor, chromatin structures or specific receptor molecule synthesis.
What is cell fate based on?
Regulatory action with regional concentration or enhancer activity.
Example of development influenced by fetal development?
Fetal alcohol syndrome
What happens in Early Development?
Development plan is established, cleavage divisions in mitosis occur in series, where embryo becomes multicellular.
What happens after embryo becomes multicellular?
The blastula forms
Blastula
A hollow sphere of cells produced during development of the embryo by repeated cleavage of the fertilized egg.
What happens after blastula formation?
Folding of the blastula in the centre of the primitive streak in gastrulation
Importance of the primitive streak?
The streak establishes the cranial axis, connecting stalk cells thicken, cells proliferate/migrate to middles of the embryo.
Three layers formed in gastrulation…
Ectoderm, Endoderm and Mesoderm
How are cell fates determined?
Blastula cells become committed to a lineage, limiting states possible.
Types of cell fate…
Either autonomous or regulated by morphogens
Morphogens
Diffusible molecules produced in restrictied tissue region that can impact specific differentiation through concentration gradients.
What is morphogen regulation based on?
Positional information, the position of cells means imposition of development
What is gene control in C.elegans dependent on?
Polar granules
Polar Granules
Transmitted cytoplasm particles mediated by microfilaments of the cytoskeleton.
Early oocyte in oogenesi…
It is diploid with cytoplasm differentiated into organized regions, determining blastula development fates
Function of oocytes..
Provide positional information, and store molecules for protein synthesis and cleavage divisions
Importance of oocyte genes….
In tandem with neighbouring cells assisting in proper organization/composition
What determines the development genes instruction?
Morphogen concentration gradients where oocyte genes expressed are important for other tissues
Why are zygotic genes not needed?
The embryo depends on its own genes
When do zygotic genes become functional?
In the two-cell stage
Why is early zygotic activation important?
Imprinting such as IGF2 imprinted on the oogenesis.
Why is the nematode useful for genetic analysis?
It has a large number of offspring and is easy to culture.
Example of apoptosis importance in cell development…
Webbed fingers in humans
Example of apoptosis mutations causing abnormalities?
The CED-3 gene causes the cell to differentiate into supernumerary neuron
Epistasis
Where the effect of a gene mutation is dependent on the presence or absense of mutations in one or more other genes.
What is development an example of?
Switch-dependent pathway.
Switch Dependent Pathway
Meaning the activity of one component either stimulates/represses the activity of the next.
How are ‘cell-fate genes’ determined?
Law of Dominance as recessive and dominant genes have opposing effects
Basis of determining cell-fate genes…
If different mutations alter cell fates in opposite directions, the product of the gene must be essential
An example of using LOD to determine cell-fate genes?
Lin-12 genes controls number of cell decisions
What cell divisions does LIN12 control?
Two cells from different linaages from the same zygote differentiate into either an anchor cell whilst the other a ventral uterine precursor cell, either as likely to differentiate into either as the other.
Epistatic Gene
A gene determining whether or not a trait will be expressed.
Hydrostatic Gene
A gene whose phenotype is altered by the expression of an allele at a seperate locus in an epistasis event
