Secondary Growth in Roots

In the dicot root, the vascular cambium is completely secondary in origin.

It originates from the tissue located just below the phloem bundles, a portion of pericycle tissue

TLS Online TPP Program

#Id: 7914

#XL - Q Biochemistry

Matrix-targeting sequences

Located at the N-terminus

Usually 20–50 amino acids in length

Rich in hydrophobic amino acids, positively charged basic amino acids (arginine & lysine), and hydroxylated ones (serine and threonine)

Amphipathicity of matrix-targeting sequences is critical to their function

TLS Online TPP Program

#Id: 7913

#XL - Q Biochemistry

Matrix-targeting sequences

sequences for localizing proteins to mitochondria

TLS Online TPP Program

#Id: 7912

#XL - Q Biochemistry

The majority of proteins located in mitochondria are not encoded by mtDNA, they are encoded by genes in the nucleus and are imported into the mitochondria after their synthesis in the cytosol.

TLS Online TPP Program

#Id: 7911

#XL - Q Biochemistry

MCSs also serve as interfaces for the transfer of ions (Ca+2 ) and small molecules (glycerophospholipids) between the ER and mitochondria.

TLS Online TPP Program

#Id: 7910

#XL - Q Biochemistry

Mitochondria-associated membranes (MAMs)

The portions of the ER membranes that form special contact regions with the mitochondria.

TLS Online TPP Program

#Id: 7909

#XL - Q Biochemistry

Membrane contact sites (MCSs)

Mitochondria establish MCSs with many other organelles, including ER, lysosomes, peroxisomes, the plasma membrane, the Golgi, endosomes, and even lipid droplets.