True or False?

Acetyl CoA is the major building block of almost all fatty acids. During fatty acid synthesis acetyl CoA are joined together to make a 16 carbon fatty acid.

There are three major steps in fatty acid synthesis.

Briefly describe the first step of fatty acid synthesis.

About 90% of patients with cystic fibrosis are at risk for fat-soluble vitamin deficiency. These patients are unable to properly digest food due to a lack of digestive enzymes made by the pancreas.

How could lack of pancreatic lipase lead to vitamin deficiency?

This is Palle-Jooseppi from Finland and he has just woken up after his winter hibernation. Even after months-long rest, he does not look happy!

Prior to his long nap, Palle has spent a lot of time eating to make sure he has enough body fat stored to use for energy production. During his nap, he goes through β-oxidation to produce sufficient energy to keep him warm.

Using your knowledge of β-oxidation describe how Palle would break down a 12 carbon saturated fatty acid to yield energy.

Activated fatty acid (fatty acyl CoA) can cross the outer membrane of mitochondria and enter the intermembrane space. Here, it undergoes another reaction.

With the help of an enzyme called carnitine acyl transferase I, the fatty acyl group is transferred onto a molecule called carnitine. This forms fatty acyl carnitine. Fatty acyl carnitine can cross the inner mitochondrial membrane with the help of an translocase enzyme and enter into the matrix.

Once inside the matrix, the carnitine is removed and a mitochondrial coenzyme A group is added back to the fatty acyl to re-form fatty acyl CoA. This reaction is catalysed by carnitine acyl transferase II. Fatty acyl CoA is now at the right location to undergo β-oxidation.

Carnitine acyl transferase I, is important because it is involved in the regulation of fatty acid breakdown (β-oxidation).

Carnitine acyl transferase I is regulated by an intermediate of the fatty acid synthesis pathway called malonyl CoA.

Which ONE of these statements is incorrect?

β-oxidation is a catabolic process where fatty acids are broken down to produce acetyl CoA. 

Where in a cell does β–oxidation occur?

True or False?

Which of the labelled steps in fatty acid oxidation shown in the diagram is the rate-limiting step?

True or False?