Modification of H2A inhibits elongation by inhibiting a histone chaperone that removes histone octamers from DNA as Pol II transcribes through a nucleosome, then replaces them as the polymerase passes. 

TLS Online TPP Program

#Id: 7479

#Unit 4. Cell Communication and Cell Signaling

IgG efficiently opsonizes pathogens for engulfment by phagocytes and activates the complement system. The affinity of the individual antigen binding sites for their antigen is therefore critical for the effectiveness of these antibodies, and most of the B cells expressing these classes have been selected in the germinal centers for their increased affinity for antigen after somatic hyper mutation.

TLS Online TPP Program

#Id: 2526

#Unit 13. Methods in Biology

The PCR involves two oligonucleotide primers, 17–30 nucleotides in length, which flank the DNA sequence that is to be amplified.

TLS Online TPP Program

#Id: 4323

#Unit 11. Evolution and Behavior

 Pasteur made a series of flasks with long, twisted necks (“swan-neck” flasks)

TLS Online TPP Program

#Id: 124

#Unit 5. Developmental Biology

The optic vesicle is able to induce lens formation in the anterior ectoderm but not in the presumptive trunk and abdomen.

TLS Online TPP Program

#Id: 2814

#Unit 13. Methods in Biology

Proteins differ in the amount of hydrophobic amino acids that are present on their surface. This difference can be exploited in salt fractionation but can also be used in a higher resolution method using hydrophobic interaction chromatography (HIC).