Lipids

Question 1

In the activation of FA, what is the enzyme responsible and where does this occur?

Answer 1

Fatty acyl CoA synthetase; cytosol

Question 2

What are the immediate substrate and product of lipogenesis?

Answer 2

Acetyl CoA; Palmitoyl CoA

Question 3

What is the rate limiting step of lipogenesis?

Answer 3

Acetyl CoA + HCO3 + ATP -> Malonyl CoA ( Acetyl CoA carboxylase)

Question 4

What are the important steps of Fatty Acid Synthesis?

Answer 4

1) transport of acetyl coa to cytosol; 2) production of malonyl CoA; 3)elongation to palmitoyl CoA

Question 5

What shuttle is used for the transport of acetyl coa to cytosol?

Answer 5

Citrate shuttle

Question 6

Enzyme involved in the production of Malonyl CoA from Acetyl CoA?

Answer 6

Acetyl CoA carboxylase

Question 7

What is the coenzyme needed for the production of Malonyl CoA?

Answer 7

Biotin

Question 8

What is the sequence of steps repeated in the elongation of Palmitoyl CoA?

Answer 8

Condensation, Reduction, Dehydration, Reduction

Question 9

What is required as donor of reducing equivalents in the reduction reactions of elongation of Palmitoyl CoA?

Answer 9

NADPH

Question 10

What are the sources of NADPH?

Answer 10

PPP, Malic enzyme, Isocitrate dehydrogenase

Question 11

Where is further elongation and desaturation happen in Lipogenesis?

Answer 11

smooth endoplasmic reticulum

Question 12

What is the structure of triglycerol?

Answer 12

3 FA esterified to a molecule of glycerol

Question 13

What are the steps of TGA synthesis?

Answer 13

1) sequential addition of 2 fatty acyl CoA to glycerol 3 phosphate; 2) removal of phosphate; 3) addition of the third fatty acyl CoA

Question 14

What are the sources of glycerol 3 phosphste in TGA synthesis?

Answer 14

1) DHAP from glycolysis; 2) Phosphorylation of free glycerol

Question 15

What is the enzyme needed to get DHAP from glycolysis and on which organs can this be seen?

Answer 15

Glycerol 3 phosphate dehydrogenase; liver and muscle

Question 16

What enzyme is needed for the phosphorylation of free glycerol and on what organ is this seen?

Answer 16

Glycerol kinase, liver

Question 17

What is the enzyme needed for the mobilization of fats during fasting?

Answer 17

Hormone sensitive lipase

Question 18

Mobilization of fats are activated by?

Answer 18

glucagon and epinephrine (phosphorylation)

Question 19

Mobilization of fats inhibited by?

Answer 19

Insulin (Dephosphorylation)

Question 20

Where does fatty acid activation occur?

Answer 20

cytoplasm

Question 21

Where does beta oxidation occur?

Answer 21

Mitochondria

Question 22

What are the substrate and products of beta oxidation?

Answer 22

Palmitate; 8 acetyl coa, 7NADH, 7FADH2

Question 23

What is the rate limiting step of beta oxidation?

Answer 23

Translocation of fatty acyl coa from cytosol to mitochondria ( Carnitine-palmitoyl transferase)

Question 24

In the degradation of fatty acyl coa, what is the sequence of repeated steps?

Answer 24

Oxidation -> Hydration -> Oxidation -> Thiolysis

Question 25

What is the enzymes collectively called in the degradation of fattyl acyl coa?

Answer 25

Fatty Acid Oxidase

Question 26

In FA with an odd number of carbons, what are the sequential enzymes involved?

Answer 26

Propionyl CoA carboxylase (biotin) and Methylmalonyl CoA mutase (vitamin B12)

Question 27

Results in the deficiency in fat soluble vitamins and essential fatty acids, manifests as steatorrhea

Answer 27

Lipid Malabsorption

Question 28

What disease is presented with hypoglycemia due to impaired fatty acid oxidation and lipid accumulation with muscular weakness?

Answer 28

carnitine deficiency

Question 29

Where does deficiency in carnitine palmitoyl transferase 1 affects?

Answer 29

Liver

Question 30

Where does carnitine palmitoyl transferase II deficiency affects?

Answer 30

cardiac and skeletal muscle

Question 31

Most common inborn error of fatty acid oxidation?

Answer 31

MCAD deficiency

Question 32

What is the toxin seen in jamaican vomiting sickness?

Answer 32

hypoglycin

Question 33

What is deficient in Refsum Disease?

Answer 33

phytanol CoA hydroxylase

Question 34

Known as cerebrohepatorenal syndrome; inherited absences of peroxisomes

Answer 34

Zellweger syndrome

Question 35

what disease is the inability to transport VLCFAs across the peroxisomal membranes leading to accumulation in the brain, adrenals, testes

Answer 35

Adrenoleukodystrophy

Question 36

What are the substrate and products of Ketogenesis?

Answer 36

Acetyl CoA; Acetoacetate, beta hydroxybutyrate, acetone

Question 37

What is the rate limiting step of ketogenesis?

Answer 37

acetoacetyl coa + acetyl coa -> hmg coa (HMG CoA synthase)

Question 38

Process of ketone body oxidation in the mitochondria of extrahepatic tissues

Answer 38

Ketolysis

Question 39

How is cholesterol stored?

Answer 39

Cholesterol esters

Question 40

What is the rate limiting step in cholesterol synthesis?

Answer 40

HMG-CoA -> Mevalonate ( HMG-CoA reductase)

Question 41

Statins are competitive inhibitors of?

Answer 41

HMG CoA reductase

Question 42

What is the most common form of CAH?

Answer 42

21 alpha hydroxylase deficiency

Question 43

11 Beta1 Hydroxylase Deficiency blocks which step in cholesterol pathway?

Answer 43

11 deoxycorticosterone to corticosterone

Question 44

In 21 alpha hydroxylase deficiency, which step in cholesterol pathway is blocked?

Answer 44

Progesterone to 11 deoxycosterone AND 17 hydroxyprogesterone to 11 deoxycortisol

Question 45

Three possible sources of amino acid pool

Answer 45

degradation and turnover of body protein, dietary intake, synthesis of nonessential amino acids

Question 46

What is the first phase of amino acid catabolism?

Answer 46

Transamination and Oxidative Deamination

Question 47

What are the enzyme and coenzyme involved in the 1st phase of amino acid catabolism?

Answer 47

aminotransferase; pyridoxal phosphate (B6)

Question 48

What are the two mechanisms of transport of ammonia from peripheral tissues?

Answer 48

through glutamine (glutamine synthetase); through alanina (glutaminase)

Question 49

What is the rate limiting step of urea cycle?

Answer 49

NH3 + CO2 -> carbamoyl phosphate (carbamoyl phosphate synthetase 1)

Question 50

What is the allosteric inhibitor of CPS 1?

Answer 50

N-acetylglutamate

Question 51

How many molecules of ATP is needed for 1 mol of urea?

Answer 51

3 mol ATP