Biochem: EXAM 2 (Ch. 22) Lipolysis, Fatty Acid Oxidation & Ketogenesis

Slides from textbook cards and edited with slideshow info

Each step in fatty acid oxidation involves _______________, is catalyzed by separate enzymes, utilizes ____ and _____ as coenzymes, and generates ATP.

Acyl-CoA derivatives, NAD and FAD

Fatty acid oxidation requires the presence of ____ to work

oxygen

_____________ is a characteristic of starvation and of diabetes mellitus and leads to increased ketone body production by the liver (ketosis).

Increased fatty oxidation

Because gluconeogenesis is dependent upon fatty acid oxidation, any impairment in fatty acid oxidation leads to _________.

Hypoglycemia

Oxidation of fatty acids occurs in ___________.

Mitochondria

Fatty acids are transported in the blood as ______________.

Free fatty acids

In plasma, longer chain FFA are combined with _______ and in the cell they are attached to a FATTY ACID BINDING PROTEIN so that in fact they are never really “free”.

Albumin

True or False: Fatty acids must be first converted to an active intermediate before they can be catabolized.

True

This is the only step in the complete degradation of a fatty acid that requires energy from ATP.

Acyl CoA synthase making Acyl CoA from free fatty acid

Long-chain fatty acids penetrate the inner mitochondrial membrane as _____________.

Carnitine derivatives

True or False: Long-chain acyl-CoA cannot penetrate the inner membrane of mitochondria.

True

Acylcarnitine is able to penetrate the inner membrane and gain access to the B-oxidation system of enzymes via the inner membrane exchange transporter _________________.

Carnitine-acylcarnitine translocase

In the ____________, two carbons at a time are cleaved from acyl-CoA molecules starting at the CARBOXYL END.

B-oxidation pathway

The B-oxidation cycle generates and _.

FADH2 and NADH

The first step of Beta Oxidation is the removal of TWO hydrogen atoms from the 2(a) and 3(b) carbon atoms, catalyzed by __ and requiring ______.

Acyl-CoA dehydrogenase,FAD

For example, after SEVEN cycles the C16 fatty acid, _ would be converted to eight acetyl CoA molecules.

Palmitate

Transport of electrons from FADH2 and NADH via the respiratory chain leads to the synthesis of ____ high-energy phosphates for each of the seven cycles needed for the breakdown of the C16 fatty acid, palmitate to acetyl-CoA. (7 x 4 = 28)

4

A total of ___ mol of acetyl-CoA is formed during Beta Oxidation of a 16 C FA and each gives rise to ___ mol of ATP on oxidation in the CTA making ___ mol total

8,10,80

_ oxidize very long chain fatty acids.

Peroxisomes

This occurs when there is a high rate of fatty-acid oxidation in the liver.

Ketogenesis

Under merabolic conditions associated with a high rate of fatty acid oxidation, the liver produces considerable quantities of (3)

Acetoacetate, acetone, and 3-hydroxybutyrate

Acetoacetate continually undergoes spontaneous decarboxylation to yield .

Acetone

Acetoacetate and 3-hydroxybutyrate are interconverted by the mitochondrial enzyme______ and the equilibrium is controlled by the mitochondrial ____ concentrations

3-hydroxybutyrate dehydrogenase NAD/ NADH

In vivo, _ appears to be the only organ in nonruminants to add significant quantities of ketone bodies to the blood.

Liver

True or False: Because there is active synthesis but LITTLE UTILIZATION of ketone bodies in the liver, while they are used but not produced in extrahepatic tissues, there is a net flow of the compounds to the extrahepatic tissues.

True

Enzymes responsible for ketone body formation are associated mainly with the ____ within the cell

Mitochondria

Two acetyl-CoA molecules formed in B-oxidation condense to form acetoacetyl-CoA by a reversal of the __ reaction.

Thiolase

This is quantitatively the predominant ketone body present in the blood and urine in ketosis

3-hydroxybutyrate

Acetoacetate once formed cannot be reactivated directly except in the _, where it is used in a much less active pathwat as a precursor in cholesterol synthesis.

Cytosol

Whatnare the precursors of ketone bodies in the liver?

Free FAs

After uptake by the liver, FFAs are either _ to CO2 or ketone bodies or ___ to triacylglycerol and phospholipid.

B-oxidized, Esterified

A fall in the concentration of _, particularly within the mitochondria, can impair the ability of the citric acid cycle to metabolize acetyl-CoA and divert fatty acid oxidation toward ketogenesis.

oxaloacetate

The basic form of ketosis occurs in ___ and involves depletion of available carbohydrate coupled with mobilization of FFA.

starvation

What leads to ketogenesis in the liver?

When there is low oxoloacetate in the CAC/ incomplete fatty acid oxidation

What other pathway is also activates when lipolysis is?

gluconeogenesis

What molecule from glycerol metabolism goes through gluconeogenesis?

DHAP

What type of fatty acids does Beta oxidation primarily deal with?

Beta oxidation

What does Acyl CoA synthase do?

It combines CoA with a fatty acid using ATP to pass through the mitochondrial membrane

What does acyl CoA need to be converted into to get INTO the mitochondria?

acylcarnitine

What molecule gets Beta Oxidizes

Acyl-CoA

Do the complete oxidation ATP production for palmitic acid (16:0)

You get 8 acetyl CoAs and you get 10 ATP per cycle of the CAC so you get 80 ATP and you get 7 beta oxidation cycles to occur so you get 7 NADH and 7 FADH which gets you 28 ATP from the ETC and then subtract 2 ATP used for the transport of acyl CoA into the mitochondria so net 106 ATP but there are 3 FA in triacyglucerol so multiply by 3

How many ATP do you get from glycerol?

14

The conversion of acetoacetate to 3-hydroxybuterate requires ____ but it is (non-spontaneous/spontanous) and (reversible/irriversible)?

NADH, spontaneous and reversible

Where do acetoacetate and 3-hydrocybuterate eventually end up?

They are converted into 2 acetyl CoAs and enter the citric acid cycle in skeletal muscle