This alteration to the structure of the chromosome is accomplished by the enzyme topoisomerase. Replication cannot occur on supercoiled DNA, only the relaxed form.

TLS Online TPP Program

#Id: 7806

#Unit 10. Ecological Principles

TEMPORAL ENVIRONMENTAL VARIATION describes how environmental conditions change over time.

TLS Online TPP Program

#Id: 9930

#Unit 4. Cell Communication and Cell Signaling

Variation in Influenza Strains

Antigenic variation in HA and NA is generated by

Antigenic drift involves a series of spontaneous point mutations that occur gradually.

Antigenic shift results in the sudden emergence of a new subtype of influenza.

TLS Online TPP Program

#Id: 9676

#Unit 4. Cell Communication and Cell Signaling

Phosphorylation by the mTORC2 kinase complex, of a second serine on

PKB that is not in the activation loop is necessary for maximal PKB activity

TLS Online TPP Program

#Id: 3986

#Unit 2. Cellular Organization

Addition of a topoisomerase greatly facilitates nucleosome association with cccDNA.

When a topoisomerase is present during nucleosome assembly, it cannot act on the DNA bound to the nucleosome. Instead, the topoisomerase relaxes the DNA not included in nucleosomes, reducing the positive superhelical density in these regions by decreasing the linking number.

TLS Online TPP Program

#Id: 7541

#Unit 6. System Physiology – Plant

Compounds such as AMO-1618, Cycocel, and Phosphon D are specific inhibitors of the first stage of gibberellin biosynthesis, and they are used as growth height reducers.