On the right side of the embryo, activin is expressed, along with activin receptor IIa. This activates Fgf8, a protein that blocks expression of the gene for Cerberus.

TLS Online TPP Program

#Id: 7215

#Unit 5. Developmental Biology

Class II, but not class I, presentation is inhibited by treatment of the cells with an agent that blocks endocytic processing within the cell (chloroquine).

TLS Online TPP Program

#Id: 1856

#Unit 3. Fundamental Processes

Promoters that do not contain a TATA element are called TATA-less promoters. Surveys of promoter sequences suggest that 50% or more of promoters may be TATA-less.

TLS Online TPP Program

#Id: 6354

#Unit 8. Inheritance Biology

Cytoplasmic Inheritance

Present in males and females. 

Usually inherited from one parent, typically the maternal parent.

Reciprocal crosses give different results. 

Exhibit extensive phenotypic variation, even within a single family. 

TLS Online TPP Program

#Id: 4540

#Unit 12. Applied Biology

For subunit vaccine, a eukaryotic cloning host is always used because the recombinant proteins produced by bacteria are nonglycosylated, and glycosylation is necessary for the proteins to be immunologically active.

TLS Online TPP Program

#Id: 2978

#Unit 3. Fundamental Processes

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