INTRODUCTION Flashcards
What is development?
The process that converts a single fertilised egg into a properly patterned, functional organism.
What processes and mechanisms drive development?
The growth of a single fertilised egg could occur non-autonomously or autonomously. At one extreme, the eff would be highly patterned through unequal distribution of components and with division their components segregated differentially. At another extreme, signals in the environment would cause cell to differentiate into different fates. In vertebrates, both of these occur.
How can we examine the processes of development?
Observation:
In situ hybridization - analysis of mRNA populations that are specific to distinct cells
Immunohistochemistry - analysis of proteins that are differentially expressed in cells
Physical Manipulation: cell transplantation, cell ablation
Genetic Manipulation: ectopic, over expression, KO of a gene, mutagenesis
Protein Manipulation: ectopic, over expression, removal of function by function blocking antibodies
What are the two major groups of factors that determine which genes are expressed in a cell?
Inducing factors (signalling molecules) expressed in other cells
Second molecules that are activated or induced upon exposure to an inducing factor.
Ultimately, fate is determined in part through its history and in part to the signals to which it is exposed.
There are 7 families of signalling molecules that are used over and over in development. They are grouped into families based on DNA sequence homology. What are they?
Members of the transforming growth factor beta superfamily. This superfamily divides into the activin-like subset and the bone morphogenetic protein subset.
Wnt Hedgehog Fibroblast growth factor Epidermal growth factor Delta/Notch Signals Eph/Ephrins
There are several classes of transcription factors are key determinants in establishing cell fate. Transcription factors vary in DNA sequence but have small regions of homologous features. What are some examples of these classes?
Homeobox domain: include Hox, Pax,Nkx
Basic helix-loop-helix: involved in specific DNA transcription
Sox: involved in neural identity
Smad: acts with cofactors to mediate BMP signalling
What is emergent behaviour?
How organisation at one level predicts and prefigures the next level.
What is developmental neurobiology?
The study of how the nervous system and its resident cell types form.
As cells divide they become specialised. If only mitosis were occurring all cells would become identical. So what is occurring?
Division and differentiation must be highly organised in space and time, in the correct shape and along the correct axes.
How do cells know what to do next?
Two kinds of information guide cell behaviour: intrinsic and extrinsic signals.
Extrinsic information is often received from where?
From a cell’s surroundings, usually from a neighbouring cell in the form of a chemical signal.
Intrinsic information comes from where>
It is inherited from the mother cell, at cell division.
If fate specifying molecules are not distributed in a uniform manner the two daughters inherit different information and are different from one another.
If every cell carries the same 20,000 genes, how do they become different from one another.
Differential gene transcription.
What happens to specialisation and pluripotency over time?
Specialisation increases.
Pluripotency decreases.
What is another theory for cells becoming different to each other despite having the same genetic material.
Gene loss.
This is is very rare occurrence.
