Developmental Genetics Flashcards
What 3 things does developmental genetics study
Differentiation , growth and morphogenesis of organisms
What are the developmental stages in humans
From fertilisation to embryo to a foetus when born
What are the 3 approaches to studying development
1- anatomical - why is that organ or tissue in that place
2- physical manipulation - eg transplanting things from one embryo to another to see effect
3- genetics - what genes control development or explain congenital malformations
What are the 6 model organisms for development
Mouse Chicken Drosophila fruit fly Frog Zebra fish C elegans worm
What genes for eye development were conserved eg in a mouse, human and drosophila with homologous genes
The pax 6 gene which it 1 allele mutated can cause missing iris
If both alleles mutated there is no eye development
What is the cardiac gene conserved in all model organisms
Nkx 2.5
What happens in both mice and humans if NKx 2.5 gene is mutated
Heart defects
What if 2 copies of the homologous gene to nkx 2.5 is mutated eg in drosophila
No heart is formed
What is the term called to describe the homeobox genes of the drosophila fruit fly?
Temporo spacial colinearity
What does temporo spacial linearity
Where genes are placed and expressed in order of where they are in body (homeobox genes transcribe the TFs)
Why is the fruit fly a model organism
Genome is sequenced
Many mutants available to their homeobox genes
SHORT LIFE CYCLE
Many eggs/offspring
Have homologous genes eg pax 6 for eye development
Which 3 model organisms are used for physical manipulation
Zebra fish
Toad
Chicken
Why are zebra fish,toad and chicken embryos easily manipulated
Toad and chicken have large eggs
The zebra fish embryo is transparent and they lay many eggs
Why can a chicken, mouse and toad be used for the anatomical approach?
Have similar anatomy eg organs are similar
Why do we need animals as models?
Due to ethics - can’t manipulate human embryos
Faster life cycles
Can’t use cell culture for drug development, complex disease processes or complex development
What are human organoids and what are they formed by
They are 3D cell cultures produced from induced pluripotent stem cells (IPSPs)
What can human organoids be used for?
Show early development stages if not full development
Create many organs eg the liver, heart
= less animal research needed
Why is the mouse most used to study genetics of development
Can induce for example knockout mice and induce human disease - many homologous genes = recombinant
Why can’t mice be used for physical manipulation studies
Because embryos are hard to get a hold of (not external like toads and chicken eggs or zebra fish)
How does chemical mutagenesis work
The chemical ENU or X-rays cause mutations (point mutations) which cause loss of function (disease)
What are morpholino oligonucleotides and Sirna job in inducing human disease
Knockdown expression of a gene
Eg sirna will bind to a risc complex and stop translation by breaking mrna
How does transgenesis cause induction of a disease
Insertion of a foreign piece of dna directly or via a vector can inhibit a gene expression via insertion inactivation
What stem cells are used to induce knockouts or knockin mutations in organisms
Embryonic stem cells
How do conditional gene modifications differ to knockouts or knockins
It’s a gene knockout but induced in specific tissue or time in development meaning no death of embryo
What is the difference between transient and germ line trans genesis
Transient doesn’t acctually go through a gene - it is a short term expression
Germline permanently alters it
Explain a way a gene can be knocked out via transgenesis instead of homologous recombination with another gene
Insertion of another gene (transgenesis) into the gene which inactivates it
Can be transient which is short term or germline
What does homologous recombination mean
Where the sticky ends bases are complementary enough to be able to cross over
What is another term for embryo development
Embryogenesis
