B-oxidation (oxidative metabolism of lipids in liver and muscle)

Question 1

what is the major source of energy in liver and muscle ,and in other tissues with the exception of bran and red cells

Answer 1

FATS

Question 2

The fatty acids oxidation proceeds in both the________and the _________?

Answer 2

peroxisomes and mitochondrion

Question 3

what are the major end products of b oxidation?

Answer 3

acetyl coa and reduced forms of FADH2 and NADH

Question 4

in the liver acetyl coa is converted into?

Answer 4

to ketone bodies (ketogenesis)

Question 5

lipolysis is regulated by hormonal mechanisms involving?

Answer 5

gucagon, epinephrine and cortisol

Question 6

fatty acids are activated by ?

Answer 6

formation of a high energy thiester bond with coenzyme A

Question 7

in blood fatty acids are bound to which molecule?

Answer 7

albumin

Question 8

the length of the fatty acid dictates?

Answer 8

where it is activated to coA

Question 9

what kind of fatty acids can pass the membrane via passive diffusion?

Answer 9

short and medium chain fatty acids

Question 10

what is the function of the carnitine shuttle?

Answer 10

bypasses the impermeability of the mitochondrial membrane to coenzyme A

Question 11

CPT1( carnitine palmitoyl transferase 1 is located in which side of the membrane?

Answer 11

outer side of mitochondrial membrane

Question 12

an acyl carnitine transporte or TRANSLOCASE in the inner membrane mediates?

Answer 12

the tranfer of acyl-carnitine in to the mitochodrion

Question 13

what is the function of CPTII

Answer 13

Regenerates the acyl coa

Question 14

the carnitine shuttle operates in which mechanism?

Answer 14

antiport mechanism

Question 15

what inhibits the carnitine shuttle ?

Answer 15

MALONYL-COA

Question 16

The common intermediate in the oxidation of carbohydrates and lipids is ?

Answer 16

ACETYL-COA

Question 17

The caloric value of fats is about ????

Answer 17

twice that of sugars

Question 18

on b oxidation, for each cycle was formed?

Answer 18

1. acetyl coa
2. FADH2
3. NADH
4. FATTY ACYL-COA with two fewer atoms

Question 19

oxidation of the B carbon(c-3) facilitates what?

Answer 19

sequential cleavage of acetyl units from the carboxyl end of fatty acids

Question 20

peroxisomes are involved in the oxidation of?

Answer 20

number of substrates, including urate, and long-,very-long and branched chain fatty acids

Question 21

peroxisomes is the principal site of production of?

Answer 21

hydrogen peroxide and account for 20% of oxygen consumption in hepatocytes

Question 22

in peroxisomes b oxidation their acyl-coa dehydrogenase is an?

Answer 22

oxidase rather than a dehydrogenase

Question 23

what is zellweger syndrome?

Answer 23

defect in import of enzymes into peroxisomes , severe multiorgan disorder leading to death usually at about 6 moths of age

Question 24

what are fibrates?

Answer 24

class of hypolipidemic drugs that act by inducing peroxisomal proliferation in liver

Question 25

which type of fatty acids yields to less FADH2 when they are oxidized?

Answer 25

unsaturated - since they are already partially oxidized

Question 26

odd chain fatty acids produce ?

Answer 26

succinyl coa from propionyl coa

Question 27

propionyl coa is converted to succinyl coa by?

Answer 27

multistep process involving three enzymes and the vitamins biotin and cobalamin

Question 28

what kind of oxidation initiates oxidation of branched chain fatty acids to acetyl coa and propionyl coa ?

Answer 28

alfa-oxidation

Question 29

what are phytanic acids?

Answer 29

branched chain polyisoprenoid lipids found in plan chlorophylls

Question 30

what is the first and essential step in catabolism of phyanic acids?

Answer 30

alfa oxidation to a pristanic acid , releasing the alfa carbon as carbon dioxide

Question 31

what is refsums disease?

Answer 31

rare neurological disorder , characterized by accumulation of phytanic acid deposits in nerve tissues as a result of a genetic defect in alfa oxidation.

Question 32

whats considered an autosomal recessive disease characterized by hypoketotic hypoglycemia , present in infancy and characterized by high concentrations of medium chain carboxylic acids, acyl carnitines and acyl glycines in plasma urine . hyperammonemia may also be present as a reuslt of liver damage

Answer 32

MCDA (medium chain fatty acyl coa dehydrogenase deficiency )

Question 33

MCAD deficiency is treated with?

Answer 33

frequent feeding, avoidance of fasting and carnitine supplementation

Question 34

defects in methylmalonyl coa mutase or deficincies in vitamin b12 lead to??

Answer 34

methylmalonic aciduria

Question 35

what is ketogenesis?

Answer 35

pathway for regenerating coa from excess acetyl coa

Question 36

in the liver the accumulation of acetyl-coa with concomitant depletion of coa, eventually limits?

Answer 36

b-oxidation

Question 37

what happens when b-oxidation of fatty acids is impaired?

Answer 37

fatty acids are oxidized, one carbon at a time , by alfa-oxidation or from the omega carbon by microsomal cytochrome P450 -dependent hydroxylases and dehydrogenases.

Question 38

during gluconeogenesis what is the primary source of ATP?

Answer 38

free coa is required to initiate and continue the cycle of b-oxidation

Question 39

in gluconeogenesis free coa is regenrated and the acetate group appears in blood in form of ?

Answer 39

3 water soluble lipid derived products: acetoacetate, b-hydroxybutyrate and acetone

Question 40

ketone bodies involves the synthesis and decomposistion of ?

Answer 40

hydroxymethylglutaryl (HMG)-CoA

Question 41

The enzymes HMG-COA synthase and lyase are unique to________?

Answer 41

hepatocytes

Question 42

the appearance of ketone bodies in the urine is an indicator of ?

Answer 42

active fat metabolism and gluconeogenesis

Question 43

ketogenesis is a result of ?

Answer 43

deficiency in carnitine metabolism

Question 44

what controls the direct rate of glycogen and glucose metabolism in liver?

Answer 44

insulin, glucagon, epinephrine and cortisol

Question 45

the process know as lipolysis is controlled by the adipocyte enzyme?

Answer 45

HORMONE SENSITIVE LIPASE

Question 46

In what kind of disease there are high blood concentrations of cortisol , hyperglycemia, muscle wastage and redistribution of fat from glucagon sensitive adipose depots to atypical sites such as the cheeks, upper back and trunk?

Answer 46

CUSHIING'S SYNDROME

Question 47

episodes of nonketotic hypoglycemia, development of fulminant heaptic failure, crdiomyopathy, rhabdomyolysis and ocassinally neuropathy and retinopathy are symptoms of ?

Answer 47

long chain l-3 hydroxyacyl coa dehydrogenase (LCAD) deficiency.

Question 48

in long chain l-3 hydroxyacyl coa dehydrogenase (LCAD) deficiency the most striking feature is ?

Answer 48

association with maternal HELLP(hemolysis,elevated liver enzymes and low platelets) and AFLP( acute fatty liver of pregnancy)