Direct-acting carcinogens

highly reactive compounds that can react with and modify nucleotide bases in DNA, to distort the normal pattern of base pairing.

TLS Online TPP Program

#Id: 7951

#Unit 2. Cellular Organization

First sugar residue is attached to dolichol by a high-energy pyrophosphate linkage & the other sugars are added by glycosidic bonds

TLS Online TPP Program

#Id: 7952

#Unit 2. Cellular Organization

Two N- acetylglucosamine (GlcNAc) and five mannose residues are added one at a time to a dolichol phosphate on the cytosolic face of the ER membrane

TLS Online TPP Program

#Id: 7953

#Unit 2. Cellular Organization

Tunicamycin

blocks the first enzyme in this pathway, inhibits the synthesis of all N-linked oligosaccharides in cells.

TLS Online TPP Program

#Id: 7954

#Unit 2. Cellular Organization

The precursor oligosaccharide is transferred from a

dolichol lipid anchor to the asparagine as an intact unit in a reaction catalyzed by a transmembrane oligosaccharyl transferase enzyme complex.

TLS Online TPP Program

#Id: 7955

#Unit 2. Cellular Organization

Only asparagine residues in the tripeptide sequences Asn-X-Ser and Asn-X-Thr (where X is any amino acid except proline) are substrates for oligosaccharyl transferase.

TLS Online TPP Program

#Id: 7956

#Unit 2. Cellular Organization

A branched oligosaccharide containing 

3 glucose (Glc)

9 mannose (Man)

2 N-acetylglucosamine (GlcNAc)

Glc3Man9(GlcNAc)2