Week 2- Cell Met II

Question 1

From what and where is acetyl coA produced?

Answer 1

From carbohydrates and fatty acids in the mitochondria

Question 2

What are the 3 sources of fat?

Answer 2

Diet
De novo biosynthesis in the liver
Adipose tissue

Question 3

Where are bile salts made?

Answer 3

Liver

Question 4

Where are bile salts stored?

Answer 4

Gall bladder

Question 5

How do bile salts pass into the small intestine?

Answer 5

Via the bile duct

Question 6

What happens if there is a lack of bile salts?

Answer 6

Lack of fat absorption causing fatty poo (steatorrhea)

Question 7

What is the name of the drug that reduces fat absorption and how does it work?

Answer 7

Orlistat- it inhibits proteases and lipases and used in the treatment of obesity (reduces fat absorption by around 30%)

Question 8

How are lipids transported?

Answer 8

By lipoproteins

Question 9

What are the 5 classes of lipoproteins?

Answer 9

Chlyomicrons, very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL), low density lipoproteins (LDL) and high density lipoproteins (HDL)

Question 10

Describe the source and role of chylomicrons

Answer 10

Come from intestine, role is dietary fat transport

Question 11

Describe the source and role of VLDL

Answer 11

Come from liver, role is endogenous fat transport

Question 12

Describe the source and role of IDL

Answer 12

Come from VLDL, role is to be a precursor to LDL

Question 13

Describe the source and role of LDL

Answer 13

Come from IDL, role is cholesterol transport

Question 14

Describe the source and role of HDL

Answer 14

Come from liver, role is reverse cholesterol transport

Question 15

What cells absorb fats in the small intestine?

Answer 15

Enterocytes

Question 16

Describe the anatomy of chylomicrons

Answer 16

Contain triglycerides, acquire lipoproteins from HDL after release into bloodstream, also contain phospholipids

Question 17

Describe the role and anatomy of lipoproteins

Answer 17

Transport hydrophobic molecules in aqueous environments, phospholipid monolayer contains cholesterol and apoproteins, inside there are cholesterol esters and triacylglycerides

Question 18

Where are LDLs taken up and by what cells?

Answer 18

By macrophages in the liver

Question 19

What is the difference between LDL and HDL?

Answer 19

LDL is bad cholesterol, it takes cholesterol to peripheral tissues
HDL is good cholesterol, it takes cholesterol from periphery to liver for use or disposal, lowing blood serum cholesterol levels

Question 20

What is beta oxidation?

Answer 20

The oxidation of fatty acids to acetyl coA in mitochondria- fatty acids have a very high calorific yield so can provide almost half the bodies energy requirement (not inc the brain)

Question 21

Describe the carnetine shuttle

Answer 21

Fatty acids are converted to an acyl coA species
Acyl coA couples with carnetine molecule to form acyl carnetine, this can be carried across the membrane (moved to and from matrix by enzyme translocase)

Question 22

What is primary carnetine deficiency?

Answer 22

When the gene that codes for carnetine is absent so acyl coA cannot be carried across the membrane.
Symptoms include muscle weakness, cardiomyopathy and hypoglycemia
Treated by taking carnetine supplements

Question 23

Describe the beta oxidation cycle

Answer 23

Acyl coA undergoes oxidation, hydration, oxidation and thiolysis to produce 1 acetyl coA and 1 acyl coA

The cycle continually removes 2C from acyl coA and on the final cycle 2 acetyl coA are formed

Question 24

What is the equation for the beta oxidation cycle starting with palmitoyl coA?

Answer 24

Palmitoyl coA + 7FAD + 7CoA + 7NAD+ goes to 8 acetyl coA + 7NADH + 7 FADH2

Question 25

What happens when acetyl coA production surpasses carbohydrate metabolism and why?

Answer 25

Carbohydrate metabolism produces oxaloacetate which is needed to allow acetyl coA to enter the TCA cycle. If not enough oxaloacetate is produced acetyl coA is converted to ketone bodies acetone, acetoacetate and D3 hydroxybutarate

Question 26

What 2 enzymes are involved with fatty acid synthesis?

Answer 26

Acetyl coA decarboxylase and fatty acid synthase

Question 27

How are fatty acids formed?

Answer 27

By decarboxylative condensation reactions involving acetyl coA and malonyl coA, after each round of elongation fatty acids undergo reduction and dehydration by sequential action of ketoreductase, dehydratase and enol reductase

Question 28

What is the carrier in beta oxidation vs lipogenesis

Answer 28

CoA vs ACP

Question 29

What provides reducing power in beta oxidation vs lipogenesis?

Answer 29

FAD/NAD+ vs NADPH

Question 30

What is the location of beta oxidation vs lipogenesis?

Answer 30

Matrix vs cytoplasm

Question 31

What is unusual about fatty acid synthesis in cancer?

Answer 31

Usually de novo synthesis is in the liver but in cancer cells there is evidence of it occurring. Targeting fatty acid synthase in cancer cells has shrunk tumors eg in ovarian cancer

Question 32

What is medium chain acyl coA dehydrogenase? What occurs when there is a deficiency in it?

Answer 32

An enzyme that catalyses a step in beta oxidation. In deficiency, patients cannot go without food for 10/12 hrs, they must have a high carb diet to prevent dependency on fatty acids for energy.