winter midterm

Question 1

glycosidic bond and composition of:

• maltose
• lactose
• sucrose

Answer 1

• alpha 1-4, 2 glucose
• beta 1-4, galactose + glucose
• alpha1-beta2, fructose + glucose

Question 2

which of the enzymes is incorrectly paired with its location of function?

Answer 2

isocitrate dehydrogenase and glyoxosome

Question 3

what does glucagon upregulate?

Answer 3

glycogen phosphorylase A

Question 4

which steps of glycolosis generate ATP? (2)

Answer 4

1,3 bisphosphate –> 3 phosphoglycerate

phosphoenolpyruvate –> pyruvate

Question 5

glycogen synthase:

Answer 5

requires glucose-1-P to be activated by UDP

Question 6

what is correct about the citric acid cycle?

Answer 6

directly generates 2 water molecules/acyl-CoA

Question 7

the structure shown below is:

Answer 7

fructose-2,6-bisphosphate

Question 8

triglyceride levels of the 4 lipoproteins

Answer 8

chylomicrons: 85
VLDL: 50
LDL: 10
HDL: 4

Question 9

which enzyme is mismatched with is function?

Answer 9

lipoamine - deamination

Question 10

which of the following is true about ketogenesis?

Answer 10

ketogenesis is absent in people with systemic carnitine deficiency

Question 11

omega oxidation of fatty acids:

Answer 11

involves sequentially alcohol, aldehyde and acid intermediates

Question 12

identify the ketone bodies (structure)

Answer 12

CH3 - C(=O) - CH2 - C (=O,O-) and

CH3 - C(H,OH) - CH2 - C (=O, O-)

Question 13

what is thiolase involved in? (4)

Answer 13

• ketogenesis pathway
• works in mitochondria
• converts acetoacetyl-CoA back into Acetyl-CoA in the peripheral tissues
• aka ACAT

Question 14

what phospho/sphingolipids are found primarily in the outer leaflet of the plasma membrane?

Answer 14

phosphotidylcholine and sphingomyelin

Question 15

peroxisomal B-oxidation of fatty acids involves:

Answer 15

• export of NADH and H+ to the mitochondria for reoxidation to NAD
• export of acetyl CoA to mitochondria to enter the CAC

Question 16

lioprotein lipase action involves:

Answer 16

activation of the enzyme by alipoprotein CII

Question 17

pyruvate kinase remains active in muscle during glycogenolysis because:

Answer 17

• muscle need glycolysis to generate energy
• muscle lacks glycogen receptors
• muscle lacks glucose-6-phosphatase

Question 18

PFK-1 is downregulated by:

Answer 18

ATP and citrate

Question 19

which of the following enzymes/pathways is correctly listed with its regualtor?

Answer 19

all of the above

Question 20

Fehlings solution?

Answer 20

• reducing sugars (glucose, galactose, fructose) interact with the solution to produce a red colour (specifically interact with the Cu ions)
• non-reducing sugars dont interact (sucrose) so theres no color change

Question 21

steps of mitochondrial B-oxidation of fatty acids to acetyl CoA:

Answer 21

occur while fatty acids are attached to coenzyme A

Question 22

pyruvate dehydrogenase:

Answer 22

• occurs in mitochondrial matrix
• converts pyruvate to acetyl CoA
• eliminates Co2/generates NADH (coupled)
• has 3 subunits and 5 coenzymes (TPP, lipoic acid, coenzyme A, FAD, NAD+)

Question 23

human G6PD deficiency results in:

Answer 23

• compromised NADPH production for antioxidant defences
• little biosynthesis of ribose-5-phosphate
• increased sensitivity to chemotherpeutic drugs

Question 24

which of the following statements about the synthesis of DHA from an essential acid in mamals is (are) correct?

Answer 24

all of the above

Question 25

during later stages of fasting, the brain becomes dependent on which of the following enzymes to efficiently generate energy?

Answer 25

thiolase, pep carboxykinase, 3B-ketoacyl CoA transferase | everything but citrate