Lectures 5-6 Flashcards
Repeat Sequences
probes are usually isolated from telomers and centromeres
telomer probes recognize 6 bp repeats at the end of a;; chromosomes
this will confirm the presence or absence of the telomeric region
Single Compy Probe
A probe isolated from a cloned DNA of disease causing gene or a fragment of DNA of known location associated with a particular gene
Use to ID the presence or absence of the gene
Subtelomere FISH
DNA sequences from region just proximal to the actual telomeric region
This region tends to be gene rich
we can ID very small deletions and rearrangemnts
Whole Chromosome Painting
Good for looking at translocations
coctail of many unique DNA fragmants used as probes
ID complex rearrangments or marker chromosomes
Critical Region
The portion that is almost always altered
this means fish can miss if deletions occur in the other portion of the gene
Contiguous Gene Syndrome
Region in genome with clusters of clossly associated genes whose normal functions are generally unrelated
Deletion of this region results in multiple phenotypic anomilies
Williams Syndrome
Deletion in the elastin gene and several of the adjacent genes
supravalvular aortic stenosis, thickening of skin and hair, skeletal or joint limitations, renal anomilies, low IQ, outgoing and friendly, blue sclera
Velocardiofacial Syndrome (VCFs)
Due to interstitial micrdeletion and then uneven crossing over causing large duplications or deletions
The actualy phenotype o child depends on the second se to alleles received from the other parent
Learning disabilities, Hypotonia, short stature, cleft lip, facial anomilies, caridac anomilies, weak immune system
Microarray
Test DNA is compared to a reference dna
They are both hybridized to different flouresent colors
yellow= equivalent
green= deletion
red=duplication
Expression Arrays
Red= high expression
Green = low expression
Black = median expression
By looking at the same gene in different tissues it is possible to determine which genes are most important in that tissue
Chromosome Microarray
Data is plotted along the length of the DNA fragment
peak= gain
trough=loss
(A normal patient would have a straight line)
Genome equivalence
All cells contain the same set of genes
Differential gene expression
only a small percentage of the genome is expressed in each cell type
At what levels is expression regulates
Differential gene transccription
Selective nuclear RNA processing
Selective mRNA translation
differential protein modfication
Cellular functions controlled by differential gene expression
Cell proliferation: producing many from one
Cell movement: rarranging cells to form structured tissues and organs
Cell specialization: creating cells with different chracteristics at different positions
Cell interactions: coordinating behavior of one cell with that of its neighbor
induction
One group of cells cjanges the nehavior of the adjacent group of cells
Short range: transmited by cell-cell interactions
long range: mediated by molecules that can diffuse through
inducers and responders
Competence
the ability of the responder to respond to the signal
Pax 6
Competence factor in the ectoderm of optic vesicle
If mutated issues with vission and nearly a complete failure of eye formtion
Paracrine
Juxtacrine
Diffusion of inducer from one cell to another
Contact betwwen the inducer and responder cell
Morphogen
Paracrine signalling molecules that cause concentration-dependant effect
Signal trasduction cascade
Binding or inducer to receptor causes conformational change
This induces enzymatic activty that phosphorylates down the line
Eventually transcription factors are induced and this changes the expression of genes
Situs Solitus
Situs Inversus
Heterotaxy
Normal
Complete mirror image
Only a subset is reversed
Deffects from left-right asymmetry
Congenital heart failure
asplenia (rt isomerism) or polysplenia (left)
Malrotation of intestines (volvulus)
How left ight asymetry is developed
- Cilia driven fluid flow in the node moves LR signals towards left side
- This is a morphogen signal
- this signal triggers nodalepression on left side
nodal activates target genes including Pitx2 (TF) and Lefty (nodal inhibitor)
lefty restricts the asymmetric domain of the nodal signal
