Following statements are regarding to recognition of sperm by mammalian zona pellucida.

A. Sperm that have undergone the acrosome reaction bind directly to zona protein ZP2 and begin making a channel toward the oocyte.

B. Sperm with an intact acrosome bind to ZP2; they undergo the acrosome reaction on the zona pellucida and then transfer their binding to ZP3.

C. When a sperm reaches the oocyte and fuses with it, the cortical granules release proteins that digest portions of ZP2 and ZP3, making them nonfunctional and prevent polyspermy.

D. When a sperm reaches the oocyte and fuses with it, the cortical granules release proteins that digest ZP3 only, not ZP2 because ZP2 involve in the process of slow block to polyspermy.

Which of the above statements are correct?

#Question id: 4510

#Unit 3. Fundamental Processes

Which statements are true about group I and group II introns,

A. Group I (and II) introns are not enzymes because they have a turnover number of only 1.

B. A third transesterification reaction can occur to cyclize the intron.

C. They cannot be readily converted into ribozymes.

D. It is similar to the way that the self-cleaving Hammerhead could be converted to a ribozyme by separating the active site from the substrate

#Question id: 4511

#Unit 3. Fundamental Processes

The proteins are not needed for the splicing reaction itself, because

#Question id: 4512

#Unit 3. Fundamental Processes

Some pre-mRNAs can be spliced in more than one way. Thus, mRNAs containing different selections of exons can be generated from a given pre-mRNA, called

#Question id: 4513

#Unit 3. Fundamental Processes

Different snRNPs recognize the same (or overlapping) sequences in the pre-mRNA at different stages of the splicing reaction, which two snRNPs recognizing the 5’ splice site

#Question id: 4514

#Unit 3. Fundamental Processes

What is true about coactivators,

A. The coactivators act directly by binding to the DNA

B. The coactivators act indirectly—not by binding to the DNA

C. Are required for essential communication between the activators and the complex composed of Pol II.

D. Are required for essential communication between the and the basal (or general) transcription factors.

#Question id: 4515

#Unit 3. Fundamental Processes

Transcription Activators are,

A. Known to facilitate transcription at hundreds of promoters,

B. Specific for a few promoters,

C. Sensitive to the binding of signal molecules,

D. Providing the capacity to activate or deactivate transcription in response to a changing cellular environment.