Glycosylase action is followed by the endonuclease APE1, which cleaves the polynucleotide chain on the 5’ side. This in turn attracts a replication complex including the DNA polymerase d/E and ancillary components, which performs a short synthesis reaction extending for two to 10 nucleotides. The displaced material is removed by the endonuclease FEN1.

TLS Online TPP Program

#Id: 6658

#Unit 3. Fundamental Processes

In the nucleus, the cap is recognized and bound by the cap binding CBP20/80 heterodimer. This binding event stimulates splicing of the first intron and, via a direct interaction with the mRNA export machinery (TREX complex), facilitates mRNA export out of the nucleus. Once reaching the cytoplasm, a different set of proteins (eIF4F) binds the cap to initiate translation of the mRNA in the cytoplasm.

TLS Online TPP Program

#Id: 4044

#Unit 2. Cellular Organization

In G-banding, chromosomes are first gently heated and then exposed to Giemsa stain; this DNA dye preferentially darkens certain regions to produce alternating dark and light G bands. Each G band is a very large segment of DNA from 1 to 10 Mb in length, containing many loops. With high-resolution G-banding techniques, a standard diploid human karyotype of 46 chromosomes is seen to contain hundreds of dark and light G bands. Not used in plants.

TLS Online TPP Program

#Id: 485

#Unit 2. Cellular Organization

Active genes/euchromatin are often found at the borders of chromosome territories, and active genes from several chromosomes may cluster in inter-chromosomal territories that are enriched in transcription machinery.

TLS Online TPP Program

#Id: 9880

#Unit 4. Cell Communication and Cell Signaling

Antimicrobial peptides generally are cysteine-rich, cationic, and amphipathic. 

Because of their positive charge and amphipathic nature, they interact with acidic phospholipids in lipid bilayers, forming pores and disrupting the membranes of bacteria, fungi, parasites, and viruses.

TLS Online TPP Program

#Id: 9932

#Unit 4. Cell Communication and Cell Signaling