Molecular Embryology

Question 1

1-2% of pregnancies are ectopic. Where do most ectopic pregnancies occur?

Answer 1

-Tubal/in the uterine tube

Question 2

What does dicer do?

Answer 2

-Cleaves double stranded RNA molecules into micro RNA

Question 3

How do micro RNA influence differentiation?

Answer 3

Micro RNA’s travel to the nucleus and controls which genes are inactivated

Question 4

Embryonic stem cells are normally obtained from which tissue?

Answer 4

Blastocyst

Question 5

What are imprinted genes?

Answer 5

• 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

Question 6

What is XIST?

Answer 6

• X Inactivation Specific Transcript

- A noncoding RNA

Question 7

What are the two ways of making sister cells different?

Answer 7

• 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)

Question 8

What determines which genes are expressed in developing tissues?

Answer 8

• Alternate splicing

- The ratio of transcription factors

Question 9

Random inactivation of one of the X chromosomes is initiated by what?

Answer 9

X-inactivating noncoding RNA(s)

Question 10

What is E-cadherin?

Answer 10

-The cadherin of the Ectoderm

Question 11

What kind of cadherin is expressed in the neural tube?

Answer 11

-N-cadherin

Question 12

How are different developmental cadherins expressed?

Answer 12

-alternative splicing

Question 13

What does a human male contribute to formation of a baby?

Answer 13

-one set of (23) chromosomes and centrioles

Question 14

What does the eve gene do in drosophila?

Answer 14

-corresponds to segments

Question 15

How is somite formation controlled?

Answer 15

• Temporal expression of regulatory genes

- (like C-Hairy-1)

Question 16

What trasmembrane protein does delta interact with?

Answer 16

Notch

Question 17

What does Notch do?

Answer 17

• Inhibits Delta production

- inhibits differentiation

Question 18

What is morphogen?

Answer 18

any factor that causes differentiation of tissues/organs

Question 19

What morphogen is secreted from the roof plate of the developing neural tube?

Answer 19

BMP

Question 20

What component of Acutane alters gene expression?

Answer 20

Retinoic Acid

Question 21

How does Retinoic Acid lead to birth defects?

Answer 21

• alters gene expression

- alter morphogen gradient during critical times in developments

Question 22

How do neurons migrate from the inner surface of then neural tube to the outer surface?

Answer 22

-Climb Radial Glia cell process

Question 23

What chemical signal do Neutrophils respond to and move towards?

Answer 23

• Formyl-Metionine
• Only bacterial proteins contain formyl-Methionine
• Neutrophil can distinguish minute changes in concentration of formyl-Methionine

Question 24

What is neurite outgrowth controlled by?

Answer 24

-NGF (Neural Growth Factor)

Question 25

What part of the neuron senses NGF?

Answer 25

Growth cone of the developing axon

Question 26

What drives the cilia at the node which directs flow of extracellular amniotic fluid that leads to left-right symmetry?

Answer 26

Dynein motor

Question 27

How does situs inversus relate to male infertility?

Answer 27

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