BSI Lecture 35-38 Lipid Metabolism/Ketogenesis Flashcards
Where are lipid/fats stored?
Adipose tissue
______ can be used as fuel via aerobic metabolism.
Triglycerides
Removal of fatty acid from triglycerides (in adipocytes) is called _______
Lipolysis
What enzyme removes fatty acids from glycerol?
Hormone-sensitive lipase
T or F? Fatty acids diffuse from adipose cells into the blood, transported to other tissues for use where they actively diffuse into the cytosol.
False, passively diffuse
What are the products after the activation of hormone-sensitive lipase?
TAG, DAG, MAG, and glycerol
T or F? Glucagon stimulates lipolysis?
True
T or F? Epinephrine inhibits lipolysis?
False, stimulates
T or F? Insulin stimulates lipolysis?
False, inhibits
When are fatty acids considered “activated”?
When CoA is added to it
T or F? Free Fatty Acid can pass through the inner mitochondrial membrane?
False, they cannot pass through
Fatty acids need to be ______ to pass through the mitochondria membranes.
Modified
T or F? Fatty acids are modified into fatty acetyl-CoA.
False, Acyl-CoA
What enzyme catalyzes fatty acids in order for it to pass through the outer mitochondria membrane?
Acyl-CoA Synthase
Fatty acyl-CoA has to be modified into __________ before it can pass through to the matrix.
Acyl-Carnitine
How is fatty acyl-carnitine transported across the membrane?
Via Carnitine/acyl-carnitine translocase
What happens to acyl-carnitine once it enters the matrix?
Carnitine palmitoyl transferase II removes carnitine and adds CoA to Acyl resynthesizing Acyl-CoA
What happens to carnitine molecule after it is removed from acyl?
It is transported out of the matrix by carnitine/acyl-carnitine translocase for reuse
What is the limiting factor for fatty acid oxidation?
Transport of fatty acid into the mitochondria matrix via the Carnitine System.
Where does Beta-oxidation occur within the cell?
Mitochondria matrix
How many steps are involved beta-oxidation?
4
_____ ______ undergo oxidative removal of successive 2-carbon units in the form of acetyl-Coa.
Fatty acids
What is produced after each cycle of beta-oxidation?
1-FADH2
1- NADH
1-Acetyl-CoA
What happens to Acetyl-CoA after it is produced via beta-oxidation?
Acetyl-CoA enters the Krebs cycle and is oxidized to CO2 and H2O
T or F? Fatty acids can be used as fuel under anaerobic conditions?
False, only under aerobic conditions
Where does the formation of ketone bodies come from?
Acetyl-CoA
Where does ketogenesis occur in the body?
In the mitochondria of the liver
What are the 3 ketone bodies?
Acetoacetate, B-hydroxybutyrate, acetone
T or F? Ketones can only be used by the liver.
False, they can be used as fuel by various tissues.
When ketone bodies are used as fuel, what happens to it once it is taken up by the cell?
It is converted back into acetyl-CoA, which can then enter the Krebs cycle
Why don’t ketone bodies normally accumulate within the body?
They are metabolized as fast as they are produced.
What is Ketogenesis?
The formation of ketone bodies from acetyl-CoA
Insulin inhibits or stimulates Ketogenesis?
Inhibits
Glucagon inhibits or stimulates Ketogenesis?
Stimulates
What can happen when ketone bodies are produced at a faster rate than the body can utilize them?
It can lead to ketosis or ketoacidosis
High beta-oxidation and low carbohydrate use can lead to ______
Ketosis (possibly ketoacidosis but rare)
When glucose levels are low OAA will be used for ______, which depletes it for the Krebs cycle.
Gluconeogenesis
T or F? High carbohydrate leads to a decrease in Krebs cycle intermediates and decreased rate of Kreb cycle.
False, low carbohydrate
Slightly elevated levels of ketone bodies is called _____
Ketosis
Uncontrolled and extreme form of ketosis is called _________
Ketoacidosis
T or F? Ketone bodies are STRONG acids
True
Extreme levels of ketone bodies can do what to the blood.
Lower pH of the blood to dangerous levels (<7.2)
Why can lowering the pH of blood be dangerous?
It impairs ability of hemoglobin to bind oxygen
Ketoacidosis will most often occur in patients with what condition?
Untreated type 1 diabetes
