Choose the correct match.

Process	Definition
a. Epithelial-mesenchymal transition	i. The phenomenon, whereby cells intercalate to narrow the tissue and at the same time lengthen it.
b. De-adhesion	ii. The process in which cells that had formerly been part of an epithelium lose their attachments and become individual, migrating cells.
c. Permissive interaction	iii. The cadherins that couple epithelial cells together are degraded, thereby allowing the cells to become free from their neighbors.
d. convergent extension	iv. The responding tissue has already been specified and needs only an environment that allows the expression of these traits.

#Question id: 3786

#Unit 3. Fundamental Processes

E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

#Question id: 3787

#Unit 3. Fundamental Processes

A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?

#Question id: 3788

#Unit 3. Fundamental Processes

The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?

#Question id: 3789

#Unit 3. Fundamental Processes

What do telomeres do?

#Question id: 3790

#Unit 3. Fundamental Processes

Semiconservative replication of DNA means that:

#Question id: 3791

#Unit 3. Fundamental Processes

 In vitro systems used to study replication must include all of the following except: