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Compared to glycogen, why are triacylglycerols considered a superior form of energy storage regarding their weight?

• triacylglycerols are stored without water of solvation

• glycogen uses water

What is the primary function of bile salts during the digestion of dietary fats in the small intestine?

• emulsify fats into mixed micelles

During the mobilisation of stored fats, what is the direct consequence of perilipin phosphorylation by Protein Kinase A (PKA)?

• phosphoorylated perlipin means its exposed and allowes hormone sensitive lipase to access TAGs

what does PKA do for FA metabolism

• phosphorylates perlipin A which coats lipid droplets

How many ATP equivalents are consumed during the activation of a single fatty acid to its fatty acyl-CoA form?

• 2

Which molecule acts as a critical inhibitor of Carnitine Acyltransferase I (CAT I), preventing the entry of fatty acids into the mitochondria?

• Malonlyl CoA

• basically saying we are actively synthesizing fatty acids so dont break them down

CAT1 function

• carnitine acyltransfrease

• allows fatty acyl coA to enter mitochondria via carnitine suttle

when is malonyl CoA produced

• during fatty acid synthesis

is palmitate saturated or unsaturated

• saturated

process of getting ready for FAS - Glucose goes thru ? which produces ? which makes ? which goes in the ? and makes ? which gets shuttled into the ? and is reformed into ? so we can start FAS

• glycolysis

• pyruvate

• acetyl CoA

• TCA cycle

• citrate

• cytoplasm

• acetyl CoA

process of getting ready for FAS - Glucose goes thru glycolysis which produces pyruvate which makes acetyl CoA which goes in the TCA cycle and makes citrate which gets shuttled into the cytoplasm and is reformed into acetyl CoA so we can start FAS

can you shuttle acetyl co A into cytoplasm

• no

• that is why we use citrate and the citrate shuttle to take citrate from mitochondria to cytoplasm

citrate reforms into ? using enzyme ?

• acetyl CoA

• ATP citrate lyase

when in cytoplasm, citrate is made into what

• acetyl coA

feedback mechanism w TCA and FAS

• when in cytoplasm, citrate is formed into acetyl CoA and oxaloacetate which is what is used in the TCA so it goes in TCA and makes more citrate

• citrate shuttled back to cytoplasm and cycle begins again

acetyl coA turns into ? w enzyme ? and ? goes in equation

• malonyl coA

• acetyl coA carboxylase aka ACC

• CO2

malonyl coA turns into ? in FAS using enzyme ? and ? goes into equation and comes out as ?

• palmitate

• fatty acid synthase

• NADPH

• NADP+

• soo it gets oxidized

rate limiting enzyme in FAS is ?

• ACC - acetyl coA carboxylase

• fatty ACCid synthesis

FAS activators

• insulin and citrate

  • FAS happens bc too much glucose and too much glucose releases insulin

FAS inhibitors

• palmotyl coA

  • downstream product of palmitate so if u have it this means u have palmitate so u dont need more

• glucagon

  • if insulin activates it, glucagon inhibits

breaking down FA is done by what process

• beta oxidation

What is the correct sequence of the four repeating reactions in the β-oxidation cycle?

1. oxidation

2. hydration

3. oxidation

4. thiolysis

   1. OHOT

beta oxidation has ? effect on carbon chains and produces ?

• shortens chain by 2 carbons

• produces 1 acetyl coA

In the complete oxidation of one molecule of Palmitate (C16​), what is the calculated net yield of ATP? gross yield? why?

• net = 106

• gross = 108 bc 2 ATP activation cost

The oxidation of odd-chain fatty acids produces Propionyl-CoA in the final round. What is the ultimate metabolic fate of this 3-carbon unit?

• converted into succinyl coA to enter TCA cycle and contribues to gluconeogenesis

• requires biotin and vitamin b12

which FA can contribute to gluconeogenesis

• only odd chain bc they product succinyl coA which goes into TCA and makes oxaloacetate which is used in gluconeogenesis

• even chain makes acetyl coA which cant be used

Why is the liver unable to use the ketone bodies it produces as an energy source?

• it lacks thiophorase which reactivates acetoacetate back into acetoacetyl coA

Which of the following describes a key structural difference between fatty acid β-oxidation and fatty acid synthesis?

• B oxidatin uses CoA

• FAS uses acyl carrier protein ACP

when is ACC active

dephosphorylated by PP2A

• ACCtually, its dephosphorylated

when is ACC inactive

phosphorylated

insulin effect on ACC

• insulin activates PP2A which dephosphorylates ACC which makes it active and therefore FAS is active

Which property of triacylglycerols makes them more efficient energy storage molecules compared to carbohydrates?

• the carbons are more reduced

Which molecule acts as the primary carrier for insoluble free fatty acids in the bloodstream?

• serum albumin

• free FA are hydrophobic and insoluble in blood so serum albumin does this by binding noncovalently to up to 10 FA

Why is the activation of a fatty acid to fatty acyl-CoA considered to cost 2 ATP equivalents?

• its going from ATP to AMP and PPI so its losing two phosphate bonds

• hydrolysis from PPi to 2Pi by inorganic pyrophosphatase

Which additional enzyme is required specifically for the oxidation of monounsaturated fatty acids like oleic acid?

• enoyl coA isomerase

• converts cis to trans bond

The final three carbons of an odd-chain fatty acid are released as which molecule?

• propinoyl coA also 1 cetyl coA

Which vitamin coenzyme is essential for the conversion of L-methylmalonyl-CoA to succinyl-CoA?

• viramin b12

Ketogenesis is accelerated when oxaloacetate (OAA) levels are low. Why does this occur?

• low OAA limits TCA cycle which is how acetyl coA gets used so it j accumulates in liver

• low OAA goes to gluconeogenesis and we have too much acetyl coA

Which molecule provides the reducing power required for the two reduction steps in fatty acid synthesis?

NADPH

In the context of diabetic ketoacidosis, why do ketone levels rise so dramatically?

• there is no insulin so noglucose uptake so just a lot of acetyl coA so overproduction of ketone bodies

What is the primary function of the 'Acyl Carrier Protein' (ACP) subunit in fatty acid synthase?

• acts as an arm that shuttles frowing fatty actyl chain between 7 active sites

Why does the condensation of two acetyl-CoA molecules during synthesis require the intermediate 'Malonyl-CoA'?

• malonyl coA pushes for the reaction to start

• direct condensation of two acetyl coA molecules is energetically unfavorale

Which tissues derive up to 80\% of its energy from the oxidation of fatty acids?

• heart andliver

why is FAS imp for animals

• hibernating animals rely entirely on stored fat going thru beta oxidation for ATP bc its higher yield

• migrating birds need endurance and lightweight energy source and they use fat instead of cabrs

During fasting, trace the hormonal signal from glucagon to TAG hydrolysis: what is the role of cAMP, PKA, perilipin, and hormone-sensitive lipase?

• cAMP

• PKA

• perlipin - provides HSL access to lipid droplet surface

• hormone sensitive lipase

role of lipoproteins

• to transfer FA throughout the blood bc there insoluble

route for lipoprotein transfer

• chylomicron » lymph » blood » tissues

lipoprotein lipase (LPL) and activator

• released when chylomicrons meet adipose or muscle tissue

• breaks TAGs into free fatty acids and glycerol

• activated by Apo C II

chylomicron: density, job, from what organ

• lowest density, takes dietary TAGs through blood, intestine (bc after food)

VLDL : density, job, from what organ

• very low density, takes liver-synthesized TAGs to tissues, liver

LDL: : density, job, from what organ

• low density, transports cholesterol into body cells made from VLDL remnants

• too much LDL is bad bc it can deposit too much cholesterol and make plaques aka bad cholesterol

HDL: : density, job, from what organ

• high density, takes excess cholesterol out of body cells and transports it back to liver, liver/intestine

• good cholesterol

What is the physiological significance of Malonyl-CoA's inhibition of Carnitine Palmitoyltransferase I (CPT-I)?

• it stops the entry of FA into mitochondria during synthesis so that it doesnt break down what it just built

• avoids futile cycle

length of fatty acid chains

• Fatty converted into? by ?

fatty acyl coA gets converted to ? in the ? by ? and goes into ? and is converted into ? by ?

goal of carnitine shuttle