Nutrition And Metabolism

Question 1

What molecule carries indgested fat through the digestive system

Answer 1

Chylomicrons

Question 2

What happens to excess dietary carbs?

Answer 2

Undergo insulin stimulated lipogenesis (glucose goes to fatty acids then to TG)

Question 3

What aretriglycerides packaged in before being secreted from the liver?

Answer 3

VLDL (Very Low Density Lipoproteins)

Question 4

What enzyme digets the TGs from chylomicrons and VLDLs to release fatty acids?

Answer 4

Lipoprotein Lipase

Question 5

What happens to excess mitochondrial citrate in lipogenesis?

Answer 5

Exported by citrate shuttle to cytosol for fatty scid synthesis and Acetyl CoA

Question 6

What is the rate limiting factor in fatty acid synthesis?

Answer 6

The carboxylation of acetyl CoA to malonyl CoA by Acetyl CoA carboxylase

Question 7

What does FAS enzyme do?

Answer 7

Condenses malonyl CoA to Acetyl-CoA to create nascent fatty acids

Question 8

What does Maonyl CoA inhibit?

Answer 8

The movement of fatty acids through the mitochondria

Question 9

Name 5 lipoproteins

Answer 9

Chylomicrons, VLDLs, IDLs, LDLs, HDLs

Question 10

Where and how are VLDLs made?

Answer 10

Made in the hepatocytes from TG, cholesterol and apolipoprotein B100

Question 11

What is reverse cholesterol transport?

Answer 11

HDLs take up excess cellular cholesterol from peripheral tissues to return it to the liver

Question 12

What does the Pentose Phosphate Pathway produce and from what?

Answer 12

Generates NADPH from NADP+

Question 13

What happens in the Oxidative stage of PPP

Answer 13

Glucose-6-Phosphate goes to 6-Phosphogluconate using Glucose-6-Phosphate Dehydrogenase. 6-Phosphogluconate then goes to Ribulode-5-Phosphate using 6-Phosphogluconate Dehydrogenase

Question 14

What is the interconversion stage of PPP and what happens to the products?

Answer 14

Ribulose-5-Phosphate goes to Glyceraldehyde-3-Phosphate and Fructose-6-Phosphate, these are shunted back into Glycolysis

Question 15

What is Steatorrhea

Answer 15

When undigested fats are found in stool samples

Question 16

What state do you enter when fasting?

Answer 16

The Basal State

Question 17

What does Insulin do to HSL

Answer 17

Insulin inactivated Hormone Sensitive Lipase

Question 18

What happens in metabolic respiration?

Answer 18

Glucose, fatty acids and amino acids are oxidised into acetyl CoA, which then enters the TCA cycle

Question 19

How do long chain fatty acids cross membranes?

Answer 19

Carnitine cycle

Question 20

What mist happen to all fatty acids before oxidation?

Answer 20

Activation, this involves forming a thioester linkage to coenzyme A to for, fatty acyl CoA

Question 21

Describe the Carnitine Shuttle

Answer 21

As CoA cannot peneratrate the inner mitochondiral membrane CPT 1 swaps CoA bound to the fatty acyl to carnitine, the Carnitine-acyl carnitine translocase transports the new fatty acyl carnitine over the mitochondrial membrane, CPT 2 then swaps the carnitine back to CoA. Free carnitine is then pumped back into the inter membrane space

Question 22

What is the fed state

Answer 22

When after eating we use fuel to make energy AND stores for later

Question 23

What is the starved state?

Answer 23

In the absense of food the body will deplete available energy stores and becoem reliant on producing its own glucose

Question 24

What is the process of oxidising fuels to CO2 and H2O to produce ATP

Answer 24

Catabolism

Question 25

Describe the insulin signalling cascade

Answer 25

Insulin binds to glucose activating
Tyrosine kinase activation and autophosphorylation. This will catalyse phosphorylation of cellular proteins resulting in the translocation of GLUT 4 transporters to plasma membranes. This will result in the uptake and storage of glucose

Question 26

Where is GLUT 1 found?

Answer 26

Blood brain barrier

Question 27

Where is GLUT 3 found?

Answer 27

Found in neurones

Question 28

Where is GLUT 4 found?

Answer 28

Skeletal muscle and adipose

Question 29

What is special about GLUT 2 and where is it found?

Answer 29

Its bi-directional and is found at the liver and kidneys