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TLS Online TPP Program

#Question id: 5667

There may be an important connection between sperm translocation and capacitation. Which of the following option is correct explanation of above statement?

#Unit 5. Developmental Biology

  1. The influx of bicarbonate ions (and possibly other ions) alkalinizes the sperm, raising its pH.

  2. before entering the ampulla of the oviduct, the uncapacitated sperm bind actively to the membranes of the oviduct cells in the narrow passage (the isthmus) preceding it.  This binding is temporary and appears to be broken when the sperm become capacitated.

  3. The cholesterol efflux from the sperm cell membrane is thought to change the location of its “lipid rafts,” isolated regions that often contain receptor proteins that can bind the zona pellucida and participate in the acrosome reaction.

  4. Capacitation is a transient event but translocation is not

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TLS Online TPP Program

#Question id: 15528

#Unit 4. Cell Communication and Cell Signaling

The B7 family of protein interact  with distinct receptor present on the T-cells, 
TLS Online TPP Program

#Question id: 15527

#Unit 4. Cell Communication and Cell Signaling

CD4 and CD8 T cells leave the thymus and enter the circulation as resting cells in which stage of the cell cycle?
TLS Online TPP Program

#Question id: 15526

#Unit 4. Cell Communication and Cell Signaling

If a thymocyte randomly generated a TCR with an affinity for MHC Class I, the TCR and CD8 would bind MHC Class I together, and generate a signal that specifically initiated a program that is 
a) silenced CD8 expression
b) silenced CD4 expression
c) induced expression of genes specific for helper T-cell lineage function
d) induced expression of genes specific for cytotoxic T-cell lineage function
TLS Online TPP Program

#Question id: 15525

#Unit 4. Cell Communication and Cell Signaling

In the instructive model, TCR/CD4 and TCR/CD8 coengagement generates unique signals, if a thymocyte randomly generated a TCR with an affinity for MHC Class I. which thymocyte would bind with MHC class I?
TLS Online TPP Program

#Question id: 15524

#Unit 4. Cell Communication and Cell Signaling

The bulk of DP thymocyte death (~95%) occurs among thymocytes that fail positive selection because 
TLS Online TPP Program

#Question id: 15523

#Unit 4. Cell Communication and Cell Signaling

The appearance of ϒδ thymocytes and αβ thymocytes during mouse fetal development. Fetal animals generate
a) more αβ T-cells than ϒδ T-cells
b) the proportion of ϒδ T-cells generated drops off dramatically after birth
c) the proportion of αβ T-cells generated drops off dramatically after birth
d) more ϒδ T-cells than αβ T cells