Lectures 3 + 4 Flashcards
Fragile X syndrome
X-linxed dominant
reduces penetrance (80% boys 30% boys)
from expansion of CGG triplet repeat
methylation of FMRI => deficiency of protein
Normal, Premutation, mutation
Full blown mutation is inherited from carrier female
EagI
Methylation sensitive enzyme = wont cut if methylation is present
mutation occurs after 200 repeats
Sickle Cell disease
Structural changes in the globin chain
2 types: HbS: GAG –> GTG
HbC: GAG–> AAG
Homo= has disease
Carriers= immune to malaria
Mnl I site
This site gets destroyed during thiese mutations and this the restriction enzymes can destinguish between A and S/C but not between S and C
Thalassemia
Deficiency of one of the chains leading to inclusion body formation by excess amounts of the other chain
Beta thalassemia
usually due to single base pair substitution
results in excess alpha with no beta to pair with so forms alpha homotetramer (heinz body)
these cause destruction of RBC
Alpha thalassemia
Beta globin cluster
due to deletions from mismatched crossovers
can loose either one or both alpha genes
Hb constant spring
mutation UAA –> CAA
this causes a stop to the production of alpha chain
tetramer of beta that will not release Oxygen
Cystic Fibrosis
Autosonal recessive
Defective CFRT gene (normally produces Cl channels)
Delta508 is a common mutation
Embryology
Developmental Biology
study of development between fertilization and birth
study of embryonic and other developmental processes
embryogenesis
when the organ primordia is established
Carnigie stages
Postovulatory stages
based on external features = arbitrary
Days since last ovulation
cleavage
increases the number of cells but not the overall size
compaction
after third division cells maximize their contact with eachotehr
segregat inner cells from outer cells
outer cells form tight junctions for stability
Blastocysts
When the inner cell mass is positionned on one side of the trophoblast cell
Cavitation
trophoblast cells excrete fluid into morula to create blastocoel (fluid filled cavity)
pluripotent
can differentiate into any cell type in the body
totipotent
can differentiate into any cell type including extraemryonic tissue
L-selectin
on the trophoblast and interacts with receptor on uterus wall causing rolling and tethering interactions
ectopic pregnancy
implantation somewhere other than uterus
cytotrophoblast
inner layer of mononucleate cells
releases proteolytic enzymes to remodel the uterine blood vessels
syncyotrophoblast
outer multinucleate cells that lack distinct bounderies
dijest uterine wall and connect the blood vessels
bilaminar germ disc
ICM differentiates into hypoblast and epiblast
primative streak and primative node
primative node is organizer tissue which expresses genes that induce formation of embryo
invagination
movement of epiblast cells through primitive streakand slps beneath it to give rise to the endoderm and mesodern
cells remaining in epiblast form ectoderm
anterior visceral endoderm (AVE)
Signals anterior-posterior axis
by expressing genes that direct the head formation
Steps of neurulation
- Formation and folding or the neural plate
- elevation of the neural crest
- convergence of the neural folds
- clolsure of the neural tube when the neural folds are brought in contact with eachother
then neural crest cells migrate away
Spina bifida
failure of closure in the posterior portion of the neural tube
Anenchephaly
Failure of neural tube to close in the anterior portion
Forbrain remains in contact with amniotic fluid and degenerates
eithelial-to-mesenchymal transition
Neural crest cells change from epithelial to loosely organized connective tissue of any origin
