120 Bfcp2A Biochemistry Fatty Acid Oxidation

Front 1

What organs/tissues do not use fat as a fuel source?

Back 1

brain and RBCs

Front 2

What's the signal for the breakdown of fat in adipose tissue?

Back 2

epinephrine or low insulin levels

Front 3

What's the enzyme that breaks down triglycerides?

Back 3

hormone sensitive lipase

Front 4

How are long chain fatty acids processed and transported?

Back 4

1. palmitic acid (C16) or other long chanin fatty acids are delivered to the cell via albumin and charged with a CoA cytosolically 2. The fatty acyl CoA is conjugated to carnitine by CPT1 in the intermembrane space of the mitocondria 3. The fatty acyl carnitine is transported across the inner mitochondrial membrane via carnitine:acylcarnitine translocase for β-oxidation

Front 5

Why will Vitamin C deficiency decrease the ability to process fatty acids?

Back 5

vitamin C is a cofactor needed to synthesize carnitine from methionine and lysine

Front 6

Which enzyme binds CoA to a fatty acid?

Back 6

fatty acyl CoA synthetase

Front 7

how many ATP equivalents are used to make a fatty acyl CoA

Back 7

2

Front 8

What inhibits CPT-I (and the fatty acid transfer process generally)?

Back 8

malonyl CoA

Front 9

What substrates are produced during fatty acid β-oxidation that can be utilized by the electron transport chain?

Back 9

FAD2H (1st step);--dehydrogenation NADH (3rd step)--hydroxyl oxidation

Front 10

What is used up and what is produced in one cycle of β oxidation?

Back 10

1 FAD, 1 NAD, 1 CoA -> 1 FAD(2H), 1 NADH, 1 Acetyl CoA

Front 11

What genetic deficiency involving β oxidation of fatty acids an lead to non-ketotic hypoglycemia?

Back 11

MCAD (medium chain acyl CoA Dehydrogenase deficiency)

Front 12

What nutrient deficiency can lead to non-ketotic hypoglycemia?

Back 12

carnitine deficiency (or Vitamin C)

Front 13

What's required for the oxidation of odd-chain fatty acids?

Back 13

The last carbon product is propionyl CoA which gets put into the citric acid cycle by being converted to succinyl CoA via a propionyl coA carboxylase, racemase, and mutase. Cofactors: biotin and B-12. Also requires ATP. Also an anaplerotic pathway for I want my MTV amino acids.

Front 14

A genetic deficiency that results in the accumlation of VLCFAs due to a lack of peroxisomes?

Back 14

Zellweger syndrome

Front 15

What accumulates in a vitamin B-12 deficiency?

Back 15

methylmalonic acid

Front 16

What complication occurs with VLCFA oxidation that is normally dealt with by the ETC during normal β-oxidation?

Back 16

FAD(2H) actually reduces oxygen to H202 requiring catalase, and the NADH produced diffuses into the cytoplasm

Front 17

How are shortened fatty acid chains in the peroxisome transported to the mitochondria for further oxidation?

Back 17

via carnitine groups

Front 18

What's the purpose of α-oxidation?

Back 18

processing of branched fatty acids from plants

Front 19

What disease is caused by a buildup of branched chain fatty acids?

Back 19

Refsum's disease

Front 20

What mechanism of fatty acid emtabolism actually oxidizes at the distal end of fatty acids (utilizing cytochrome P450 and NADPH in the ER in the process), resulting in dicarboxylic acids?

Back 20

ω-oxidation

Front 21

What are ketone bodies formed from and when are the formed?

Back 21

Ketone bodies are formed from acetyl CoA In the liver when oxaloacetate is low due to gluconeogenesis.

Front 22

What are the ketone bodies?

Back 22

acetoacetate, β-hydroxybutyrate, and acetone (not utitilizable)

Front 23

When are ketone bodies synthesized and where does this occur?

Back 23

Ketone bodies are synthesized by the liver mitochondria when oxaloacetate is low.

Front 24

Why does the TCA cycle shutdown during fasting?

Back 24

The liver uses oxaloacetate and malate to perform gluconeogenesis leaving an excess of acetyl CoA.

Front 25

Why do acetoacetate and β-hydroxybutyrate (ketone bodies) get converted back to acetyl CoA in muscle tissue?

Back 25

Muscle tissue is not gluconeogenic, so it has plenty of TCA intermediates and preferentially follows this pathway.

Front 26

What is the general process by which ketone bodies are formed from Acetyl CoA?

Back 26

There are basically two condensation steps where acetyl CoA comes together and CoA leaves as a leaving group. After the third acetyl CoA joins the other two (acetoacetyl CoA), the second acetyl CoA can depart as a leaving group through the action of HMG CoA lyase, leaving the ketone body acetoacetate.

Front 27

How can one estimate the NADH:NAD ratio in the mitochondria?

Back 27

Measure the ratio of β-hydroxy-butyrate:acetoacetate

Front 28

How can one estimate the NADH:NAD ratio cytosolically?

Back 28

Measure the ratio of lactate:pyruvate

Front 29

How are ketone bodies converted back to acetyl CoA in muscle tissue?

Back 29

Acetoacetate is converted to acetoacetyl CoA by donation of a CoA from succinyl CoA via a transferase. This cannot occur in the liver. Acetoacetyl CoA Is then split into 2 acetyl CoAs via thiolase and the input of a CoA.

Front 30

Why do high NADH levels correspond with ketosis?

Back 30

High NADH levels (which occur with low ATP levels) drive the oxaloacetate-malate equilibrium to malate preventing the continuation of the TCA cycle.

Front 31

What's the significance of an anion gap with someone who is thought to be ketotic?

Back 31

Large anion gaps indicate the presence of ketone bodies and their corresponding carboxylic acids.