Molecular Embryology Flashcards
1-2% of pregnancies are ectopic. Where do most ectopic pregnancies occur?
-Tubal/in the uterine tube
What does dicer do?
-Cleaves double stranded RNA molecules into micro RNA
How do micro RNA influence differentiation?
Micro RNA’s travel to the nucleus and controls which genes are inactivated
Embryonic stem cells are normally obtained from which tissue?
Blastocyst
What are imprinted genes?
- Genes that remain inactivated at the one cell stage
- Occurs on one of the chromosomes in egg/sperm development
- Very few cases, ~80 genes
- Best hypothesis: Males want their offspring to survive and grow in utero
What is XIST?
- X Inactivation Specific Transcript
- A noncoding RNA
What are the two ways of making sister cells different?
- Asymmetric division : sister cells born different
- Symmetric division: Sister cells become different as a result of influences acting on them after their birth (Paracrine signalling)
What determines which genes are expressed in developing tissues?
- Alternate splicing
- The ratio of transcription factors
Random inactivation of one of the X chromosomes is initiated by what?
X-inactivating noncoding RNA(s)
What is E-cadherin?
-The cadherin of the Ectoderm
What kind of cadherin is expressed in the neural tube?
-N-cadherin
How are different developmental cadherins expressed?
-alternative splicing
What does a human male contribute to formation of a baby?
-one set of (23) chromosomes and centrioles
What does the eve gene do in drosophila?
-corresponds to segments
How is somite formation controlled?
- Temporal expression of regulatory genes
- (like C-Hairy-1)
What trasmembrane protein does delta interact with?
Notch
What does Notch do?
- Inhibits Delta production
- inhibits differentiation
What is morphogen?
any factor that causes differentiation of tissues/organs
What morphogen is secreted from the roof plate of the developing neural tube?
BMP
What component of Acutane alters gene expression?
Retinoic Acid
How does Retinoic Acid lead to birth defects?
- alters gene expression
- alter morphogen gradient during critical times in developments
How do neurons migrate from the inner surface of then neural tube to the outer surface?
-Climb Radial Glia cell process
What chemical signal do Neutrophils respond to and move towards?
- Formyl-Metionine
- Only bacterial proteins contain formyl-Methionine
- Neutrophil can distinguish minute changes in concentration of formyl-Methionine
What is neurite outgrowth controlled by?
-NGF (Neural Growth Factor)
What part of the neuron senses NGF?
Growth cone of the developing axon
What drives the cilia at the node which directs flow of extracellular amniotic fluid that leads to left-right symmetry?
Dynein motor
How does situs inversus relate to male infertility?
The same Dynin motor that drives the node cilia to flow embryionic fluid is found in the cilia of sperm. 50% of infertile men have situs inversus
