Group II mitochondrial introns are excised by the same mechanism as nuclear pre-mRNAs via a lariat that is held together by a 2’–5’ bond.

TLS Online TPP Program

#Id: 8185

#Unit 2. Cellular Organization

Two types of plant peroxisomes:

Present in leaves - participates in photorespiration.

Present in germinating seeds (glyoxysomes) - converts fatty acids into sugars.

TLS Online TPP Program

#Id: 8186

#Unit 2. Cellular Organization

Glyoxysomes

Conversion of fats to sugars is accomplished by a series of reactions known as the Glyoxylate cycle

TLS Online TPP Program

#Id: 8187

#Unit 2. Cellular Organization

Biosynthetic function of animal peroxisomes- 

Synthesis of cholesterol and dolichol 

Synthesis of bile acids in the liver 

Catalyze the first reactions in the formation of Plasmalogens

TLS Online TPP Program

#Id: 8188

#Unit 2. Cellular Organization

Plasmalogens

• most abundant class of PL in myelin sheaths

• Analogous to PC

• Contain an unusual fatty alcohol that is attached through an ether linkage.

TLS Online TPP Program

#Id: 8189

#Unit 2. Cellular Organization

C-terminal peroxisomal signal sequences Ser–Lys–Leu (PTS1)

N-terminal peroxisomal signal sequences slightly longer and partially hydrophobic (PTS2)

TLS Online TPP Program

#Id: 8190

#Unit 2. Cellular Organization

Peroxins

Catalyse peroxisomal protein import by ATP hydrolysis.