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Question 1

Where does fatty acid oxidation occur?

Answer 1

Location: Occurs in the mitochondria.

Question 2

What are the general steps of fatty acid oxidation?

Answer 2

Fatty acids (stored as triglycerides) are broken down into acetyl-CoA. • Acetyl-CoA enters the Krebs cycle to produce ATP

Question 3

What two steps of the krebs cycle are inhibted when there is suffiecent energy and sufficent NADH?

Answer 3

isocitrate dehydrogenase • α-ketoglutarate dehydrogenase complex

Question 4

What is the consquence of krebs cycle inhibtion due to ATP and NADH accumlation?

Answer 4

No Krebs Cycle → build-up of citrate: • When the Krebs cycle slows down

Question 5

What are the three general steps of fatty acid synthesis?

Answer 5

1.Transfer of Acetyl-CoA from the Mitochondria to Cytoplas 2.Activation of Acetyl-CoA to form Malonyl- CoA. 3. Long Carbon Chain Synthesis Cyclic Addition and Reduction of Two Carbon Units

Question 6

What is the first step of the first stage of FA synthesis and what enzyme is used?

Answer 6

1. Acetyl CoA > Citrate a. Enzyme: Citrate Synthase

Question 7

What is the second step of the fist stage of FA synthesis; what enzyme; what is required and what is it stimulated by?

Answer 7

Citrate → Acetyl CoA + OAA ;Enzyme: ATP-citrate lyase ;REQUIRES ATP ;Stimulated by insulin.

Question 8

What is the third step of the fist stage of FA synthesis; what enzyme also?

Answer 8

OAA → Pyruvate + NADPH; Enzyme: Malate Dehydrogenase + Malic Enzymegives u NADPH+)

Question 9

Why is OAA converted into pyruvate?

Answer 9

Provides fatty acid synthesis with a source of electrons and [H +] bc it also yields NADPH

Question 10

What is the first step of stage 2; what enzyme; what does it require?

Answer 10

Acetyl CoA → Malonyl-CoA ;Enzyme: Acetyl CoA Carboxylase (ACC)Requires Biotin AND ATP

Question 11

WHat is the regulated and commited step of FA synthesis?

Answer 11

Acetyl CoA → Malonyl-CoA Enzyme: Acetyl CoA Carboxylase (ACC)

Question 12

What are the three functional components of Acetyl CoA carboxylase involved in malonyl CoA synthesis?

Answer 12

Biotin carrier protein Biotin carboxylase and Transcarboxylase

Question 13

What is the function of biotin carboxylase and how does it work and what does it require?

Answer 13

responsible for activating CO₂ to form malonyl-CoA. It attaches the activated CO₂ to a special biotin ring. Biotin is a B-vitamin that acts as a carrier forfo r the CO₂ molecule. Requires ATP.

Question 14

What is the function of Biotin Carrier Protein?

Answer 14

s like a “biotin arm” that physically moves the activated CO₂from the biotin carboxylase to transcarboxylase.

Question 15

What is the function of Transcarboxylase?

Answer 15

Function: • takes the activated CO₂ and attaches it to acetyl-CoA/ • Result: • produces malonylCoA.

Question 16

What are the two isoforms of Acc?

Answer 16

ACC1 and ACC2

Question 17

Where is ACC 1 found in the cell and what is its function?

Answer 17

• Function: Makes malonyl-CoA for fatty acid synthesis. • Location: Stays in the cytosol

Question 18

Where is ACC 2 found in the cell and what is its function?

Answer 18

Found in the outer mitochondrial membrane of the liver

Question 19

What is the signifcance of inhibtin CPT1?

Answer 19

If ACC2 is active → Malonyl-CoA increases → CPT1 is blocked → Fatty acid oxidation is inhibited.

Question 20

What are the three allosteric molecules that bind to acc and what does each one do?

Answer 20

1.Citrate (activator): . Promotes polymerization of ACC1 which increases ACC1’s activity 2. Palmitoyl-CoA (inhibitor): . Feedback inhibition 3. Glutamate (activator): activate ACC

Question 21

WHat are the hormones that regulate ACC and how do they do it?

Answer 21

insulin and citrate cause Phosphatases activate → Dephosphorylation → ACTIVE ACC. High Glucagon and High Epinephrine → AMP-activated Protein Kinases Activate → cAMP increases → Adds Phosphate to ACC → Inactive ACC dimer.

Question 22

What is the mechanisim of ACC prolonged regulation?

Answer 22

.Prolonged High Calorie Consumption: • If the body has been consuming calories for an extended period

Question 23

What is the difference between saturated and unsaturated fatty acids?

Answer 23

Saturated fatty acids have no double bonds. Unsaturated fatty acids have one or more double bonds.

Question 24

What is the main form of fat storage in adipose tissue?

Answer 24

Triglycerides (TAGs).

Question 25

What is the composition of a triglyceride?

Answer 25

TAGs are composed of Glycerol Phosphate + 3 Fatty Acids.

Question 26

Which fatty acids can the liver and adipose tissue synthesize?

Answer 26

They can synthesize fatty acids except for linoleic and linolenic acids.

Question 27

What are the essential fatty acids?

Answer 27

Linolenic acid (ω-3) and linoleic acid (ω-6).

Question 28

What is the role of essential fatty acids in cell membranes?

Answer 28

They are important in membrane phospholipids and help maintain normal fluidity of cell membranes.

Question 29

Where is Arachidonic Acid sourced from?

Answer 29

It is derived from Linoleic acid (an omega-6 fatty acid).

Question 30

What is the role of Arachidonic Acid?

Answer 30

It serves as a precursor for eicosanoids; which are signaling molecules.

Question 31

What are eicosanoids and what is their function?

Answer 31

Eicosanoids are paracrine molecules that act on nearby cells (short-lived signals). They are involved in inflammation; blood clotting; immune responses; and other key physiological processes.

Question 32

What are some symptoms of essential fatty acid deficiency?

Answer 32

Impaired growth; skin lesions; and reduced immune function.

Question 33

What is the general outline of Stage 3 of Fatty Acid Synthesis (Long Carbon Chain Synthesis)?

Answer 33

This stage involves a cycle of Condensation; Reduction; Dehydration; and Reduction.

Question 34

What enzyme is responsible for Stage 3 of Fatty Acid Synthesis?

Answer 34

Fatty Acid Synthase.

Question 35

What does Fatty Acid Synthase synthesize and what does it require?

Answer 35

It synthesizes palmitate (16:0). It requires NADPH (electrons and H+).

Question 36

How are the substrates loaded onto Fatty Acid Synthase and what are the enzymes?

Answer 36

Acetyl Transacylase: Attaches Acetyl-CoA (the starting unit). Malonyl Transacylase: Attaches Malonyl-CoA (used to elongate the chain). Both of them attach to ACP.

Question 37

What happens in the Condensation step (Stage 3)?

Answer 37

Malonyl CoA + Acetyl CoA → Beta-keto product + CO₂. •Acetyl CoA donates 2 carbons. •Malonyl CoA has 3 carbons; but 1 carbon is lost as CO₂. • Two carbons from Malonyl CoA are incorporated. This forms a 4-carbon chain.

Question 38

What happens in the first Reduction step (Stage 3)?

Answer 38

The beta-keto group (-C=O) formed in condensation is reduced to an alcohol (-OH). This step uses NADPH.

Question 39

What happens in the Dehydration step (Stage 3)?

Answer 39

The alcohol (-OH) is removed as water (H₂O); creating a double bond (-C=C-) in the chain.

Question 40

What happens in the second Reduction step (Stage 3)?

Answer 40

An NADPH molecule provides electrons and hydrogens (H+) to reduce the double bond back to a single bond.

Question 41

How does the fatty acid chain grow during Stage 3?

Answer 41

After the cycle of condensation; reduction; dehydration; and reduction; the 4-carbon fatty acid undergoes another condensation step with a new Malonyl-CoA; adding 2 more carbons. This cycle repeats until the chain reaches 16 carbons (Palmitate; 16:0).

Question 42

What modifications can be made to palmitate after synthesis?

Answer 42

Other enzymes can modify palmitate: • Elongation: Enzymes in the endoplasmic reticulum (ER) can add more 2-carbon units (e.g.; making stearate; 18:0). • Desaturation: Desaturase enzymes in the ER introduce double bonds; converting saturated fatty acids into unsaturated ones.

Question 43

Outline the steps of Glycerol Synthesis?

Answer 43

Pyruvate → Oxaloacetate using Pyruvate Carboxylase. 2. Oxaloacetate → PEP using PEP Carboxykinsae. 3. PEP → dihydroxyacetone phosphate (DHAP). 4. DHAP → Glycerol 3-phosphate using glycerol 3-phosphate dehydrogenase. 5. Glycerol 3-phosphate + 3 fatty acyl CoA → Triacylglycerol.

Question 44

What are Glitazones (TZDs) and how are they used in Type II diabetes?

Answer 44

Glitazones are drugs used to treat Type II diabetes. They induce PEP carboxykinase activity; which increases the rate of glyceroneogenesis (synthesis of glycerol 3-phosphate from non-carbohydrate precursors like pyruvate/OAA).

Question 45

How do Glitazones help treat Type II diabetes?

Answer 45

By increasing glyceroneogenesis; Glitazones increase the synthesis of TAGs in adipose tissue. This helps to decrease free fatty acids (FFA) in the blood by incorporating them into stored TAGs; which improves insulin sensitivity.

Question 46

How does Type I Diabetes affect fatty acid metabolism?

Answer 46

There is no insulin. This leads to decreased fatty acid synthesis. Acetyl CoA is converted to ketone bodies instead. People in severe ketosis may have the smell of acetone or fruity breath.

Question 47

How does Type II Diabetes affect fatty acid metabolism?

Answer 47

There is no response to insulin. This results in elevated FFA in the blood. Glucose uptake by muscles is decreased because muscles respond less to insulin. TZDs help by activating PEP carboxykinase; leading to more glycerol synthesis which combines with elevated FFAs to make TAGs.