Development Flashcards
First region in embryo to gastrulate
Grey crescent region
Waddington landscape states that cell fate and and potency…
Cell fates becomes more restricted with time, and cell fate decisions are irreversible.
Potency decreases with time
Mechanisms of gene duplication include:
Tandem, Whole genome & Segmental duplication’s
What did Gurdon and Yamanaka’s experiments show?
Adult cells can be reprogrammed to an embryonic pluripotent state.
Differentiated cells retain all genes required for development of an organism.
Dictostelium discoidum used for study of
Social behaviour
Cheating
Altruism
Arsbidopsis thaliana is what sort of model
Genetically tractable plant model
Caenorhabditis elegans are useful in studying reproduction and
self-reproduction in hermaphrodites
Drosophila melanogaster is what sort of genetic model
Genetically tractable insect model
Ciona intestinalis
basal chordate
Danio rerio’s embryos possess what feature and how is this useful
Transparent embryos, external development
Xenopus laevis are useful for studying
Good system for transplantation experiments, external development
Mus musculus useful to study as
Strong genetics, mammal
2 mechanisms of subfunctionalisation
- Change protein sequence
- Change time/place of expression
Allotetraploidy
Hybridization between two separate species
Autotetraploidy
Duplication of genome through improper meiosis
Paralogous gene
Homologous genes that have evolved by duplication and code for protein with similar, but not identical functions
Orthologous gene
Genes descending from a common ancestor encoding proteins with the same function in different species
Evidence that hox gene expression gives positional identity along A-P axis
Expression pattern
Comparative embryology
Gene knockout experiments
How are vertebrae hox genes generated?
Through tandem and segmental duplication events
How are hox genes expressed?
In spatial domains along AP
Hox genes possess spatial collinearity, what is this?
Order of expression domains of Hox genes along A–P axis of embryo corresponds with the order of the genes along the chromosome
Hox genes possess temporal collinearity, what is this?
Correlation between the spatial ordering of Hox genes within their clusters (3′ –> 5′) and the time of their first expression (earlier to later) during embryonic development
What is a hox gene?
A set of transcription factors which code for the A-P axis and determine each body segment in organisms (mainly in early embryonic development).
Forward genetics
Screen for phenotypes first
Then identifies the genetic basis which gives rise to phenotype
Genetic basis
Which genes are mutated
Reverse genetics
Begin with gene and ask what phenotype arises if that gene is mutated.
By knocking out or mutating the gene and then observe the phenotype.
Where are all the hox genes positioned in the genome?
Clustered next to each other.
Lower number hox genes are encode segments located….
Anterior
Higher numbered hox genes encode segments located….
Posterior
Spatial collinearity
Arrangement of hox genes anterior to posterior
Temporal collinearity
Arrange of hox genes based on time of expression. Anterior are expressed earlier than posterior.
Effects of radiation
- Aplastic anemia
- Nausea and vomiting
- Loss of hair
Aplastic anemia
Decrease in blood counts
Caused by radiation
First method found to repopulate blood lineages long term
In vivo bone marrow transplantation or hematopoietic stem cells
Conditions treated with bone marrow transplants
Myeloid leukemia
Lethally irradiated individauls
