Lecture 7: Cleavage II Flashcards
Genomic imprinting
Differential gene expression depending on whether chromosome is inherited from male or female parent (due to DNA methylation)
Prader-Willi Syndrome
Mutation inherited from father (deletion in long arm of chromosome 15); small hands/feet, short stature, MR, obesity
Angelman Syndrome
Mutation inherited from mother (deletion in long arm of chromosome 15); frequent laughter, seizures, uncontrolled muscle movement
X-inactivation
Dosage compensation by inactivating one X chromosome in order to have an equal amount of genetic material between males and females
Xist gene
Produces RNA molecule that coats the X chromosome and induces X inactivation by methylation
Barr body
Inactive X chromosome - only seen in females
Regulation
Ability of embryo to compensate for removal of structures or addition of structures
Chimeras/mosaics
Single cell in early cleavage injected into blastocoel of genetically different host
Fate mapping
Follows cell differentiation and shows totipotency of blastomeres
Production of tetra/hexaparental embryos
Combines material of 2-3 embryos; chimeras can be produced this way
Deletion/ablation experiments
Removing part of embryo and observing changes
Addition experiments
Adding to the embryo and observing changes
Transgenic embryos
Injection of foreign DNA into pronuclei
Knock-out experiments
Inactivation of specific genes/gene products
Fraternal/Dizygotic twinning
Product of the fertilization of 2 eggs
Identical/Monozygotic twinning
Product of fertilization of a single egg
Most common form of monozygotic twinning
Splitting of ICM in blastocyst forms 2 embryos with a common trophoblast
Conjoined twinning
ICM fails to split or rejoins at some point in development
Parasitic twinning
Smaller, but complete body portion attached to host twin
Bateson’s Rule
When duplicated structures are joined during critical developmental stages, one structure is the mirror image of the other
