Transport In Mitochondria

What is the primary function of mitochondria?

Energy production; specifically, the production of large amounts of ATP.

What are the outer membrane structures of mitochondria perforated with?

Large channels called porins, which allow entry of molecules less than 5000 kDa.

What is the role of the H+ gradient across the inner mitochondrial membrane?

It drives ATPase for ATP synthesis.

What type of genetic material do mitochondria contain?

Circular mitochondrial DNA (mtDNA), which is double-stranded.

What are the characteristic folds of the inner mitochondrial membrane called?

Cristae.

How are mitochondrial precursor proteins imported?

As unfolded polypeptide chains, aided by chaperones.

What is the function of chaperones during protein import into mitochondria?

They bind to newly synthesized polypeptide chains to prevent them from folding before docking with the TOM complex.

Which translocator complex recognizes the N-terminal signal sequence of proteins destined for the mitochondrial matrix?

TOM complex.

What is the mitochondrial life cycle dynamic process involving fission and fusion?

Mitophagy.

What function do peroxisomes serve in the liver?

They play a role in detoxification, converting 25% of alcohol.

What reaction do peroxisomes catalyze to remove hydrogen atoms from organic compounds?

RH2 + O2 -> R + H2O2.

What is the approximate size of mitochondrial DNA?

Approximately 15-17 kbp.

How do proteins move into the inner mitochondrial membrane?

Using the TOM and TIM23 translocators.

What is a significant problem with inserting proteins into the outer mitochondrial membrane (OMM)?

TOM cannot insert proteins into phospholipid bilayers.

What distinguishes multipass inner mitochondrial membrane proteins during import?

They move through TOM as loops to prevent folding and guide towards TIM22.

How are porins characterized in mitochondrial outer membrane?

They are beta-barrel proteins.

What happens to pyruvate before it enters the TCA cycle in mitochondria?

CO2 is removed from pyruvate.

What happens to the signal sequence after the protein translocates into the mitochondrial matrix?

It is cleaved off.

What is the key enzyme process occurring in the mitochondrial matrix?

The Krebs Cycle.