In most mammalian tissues, ubiquinone (also called coenzyme Q) has 10 isoprene units.

Dolichols of animals have 17 to 21 isoprene units (85 to 105 carbon atoms), bacterial dolichols have 11, and those of plants and fungi have 14 to 24.

TLS Online TPP Program

#Id: 7934

#Section 3: Genetics, Cellular and Molecular Biology

The two key components in protein targeting in ER:

Signal recognition particle (SRP)

SRP receptor

TLS Online TPP Program

#Id: 7933

#Section 3: Genetics, Cellular and Molecular Biology

Signal sequences

contain one or more positively charged amino acids adjacent to a continuous stretch of 6–12 hydrophobic residues (known as the hydrophobic core)

TLS Online TPP Program

#Id: 7932

#Section 3: Genetics, Cellular and Molecular Biology

Signal sequence

ER targeting sequence, located at the N-terminus of the protein

TLS Online TPP Program

#Id: 7931

#Section 3: Genetics, Cellular and Molecular Biology

Microsomes

when cells are homogenized, the rough ER breaks up into small closed vesicles with ribosomes on the outside

TLS Online TPP Program

#Id: 7930

#Section 3: Genetics, Cellular and Molecular Biology

Secretory pathway

pathway of protein trafficking that flows through the ER

TLS Online TPP Program

#Id: 7929

#Section 3: Genetics, Cellular and Molecular Biology

The ER captures selected proteins from the cytosol as they are being synthesized. These are of two types:

Transmembrane proteins

Water-soluble proteins