Fat metabolism

Question 1

What are the functions of nonessential lipids?

Answer 1

• act as energy source
• isolate against cold
• protect vital organs against damage

Question 2

What is the function of essential lipids?

Answer 2

must be eaten to serve as precursors of essential chemical messengers

Question 3

Which fatty acids have a straight carbon chain without double bonds?

Answer 3

Saturated fatty acids

Question 4

Which double bond makes a bend in unsaturated FA? (cis or trans)

Answer 4

Cis FA

Question 5

What kind of FA is easily oxidized?

Answer 5

• Unsaturated
• Gives an unpleasant taste and odor

Question 6

Which FA has the lowest melting point? (saturated or unsaturated)

Answer 6

• Unsaturated
• Oil

Question 7

Hvilke slags fedtsyrer indeholder hhv. animalsk og plantefedt mest?

Answer 7

Animalsk: mættede/saturated
Plante: Umættede/unsaturated

Question 8

Which are the most important essential fatty acids, and which ratio of them is best to have in the diet?

Answer 8

• linoleic acid = omega 3
• alfa-linoleic acid = omega 6
• 4:1 ratio of omega 6 to omega 3

Question 9

Where can PUFAs be found in the body? (PUFA = poly unsaturated fatty acid)

Answer 9

• In blood as unesterified FA
• Esterified to more complex lipids such as cholesteryl esters and phospholipids
• Converted into oxylipin

Question 10

What effect does oxylipin have in the body?

Answer 10

Regulate inflammation, pain response, cell adhesion, migration and proliferation, apoptosis, angiogenesis, blood coagulation

Question 11

What does high and low levels of leptin secretion signal?

Answer 11

• High levels signal sufficient energy and gives a feeling of satiety (mæthed)
• Low levels stimulate food intake

Question 12

When is adiponectin secreted from the adipocytes and what does it signal?

Answer 12

• When in caloric restriction
• Increases breakdown of fatty acids
• decreases gluconeogenesis

Question 13

How are phospholipids composed?

Answer 13

• one glycerol
• two fatty acids
• one phosphate
• one amino acid

Question 14

What are the four principal phospholipids in animal tissue?

Answer 14

• phosphatidylinositol
• phosphatidylserine
• phosphatidylethanolamine
• phosphatidylcholine

Question 15

Adioocytes in (VAT or SAT?) are more metabolically active, has a greater capacity to generate free fatty acids and are more insulin resistent

Answer 15

VAT = visceral adipose tissue

Question 16

Cholesterol changes the membrane in fluidity in what way?

Answer 16

• Decreases fluidity at high temperature
• Increases fluidity at low temperature

Question 17

(VAT or SAT?) is the most active in absorption of circulating free FA and TAG

Answer 17

SAT = subcutaneous adipose tissue

Question 18

When and why does blood plasma appear cloudy/turbid?

Answer 18

After a meal with high fat content, due to the insoluble chylomicrons containing high levels of TAG

Question 19

Hvilken slags molekyler fragter fedtsyrer fra leveren til væv? Hvilken pathway er det en del af?

Answer 19

VLDL. Den endogene pathway

Question 20

Fat is stored as __ in adipose tissue and can be mobilized by the reaction __, which liberate __ and glycerol.
Insert: ( Beta-oxidation, FFA, TAG)

Answer 20

TAG, Beta-oxidation, Free fatty acids

Question 21

Which hormones are key regulators in FFA oxidation and TAG synthesis?

Answer 21

Insulin stimulate TAG synthesis.
Glucagon stimulates FFA oxidation

Question 22

(Insert glucose og fatty acid)
__ is the preferred energy source and __ is
saved when whenever possible.

Answer 22

Fatty acids, glucose

Question 23

When and where are ketone bodies produced?

Answer 23

In the liver in times of caloric restriction, or lack of carbohydrates in the diet

Question 24

How are ketone bodies used as energy source?

Answer 24

Brain or muscle tissue convert ketone bodies to acetyl CoA, which take part in the citric acid cycle

Question 25

What decreases the melting point of lipids the most?

Answer 25

Polyunsaturated fatty acids with cis bonds

Question 26

Which lipoproteins transports fat from the intestine to the liver?

Answer 26

Chylomicron remnants and chylomicron

Question 27

How is atherosclerosis developed? (åreforkalkning)

Answer 27

Accumulated oxidized LDL is taken up by macrophages and over time the macrophages will develop into foam cell

Question 28

β‐oxidation refers to the sequential removal of two‐carbon units from acyl chains, what is the end product?

Answer 28

Acetyl‐CoA

Question 29

What kind of fatty acids are found in the human body?

Answer 29

Mostly cis ‐fatty acids, however some trans are found in the eyes

Question 30

Where does β‐oxidation take place?

Answer 30

In mitochondria and peroxisome

Question 31

How do fats play a role in cell signaling?

Answer 31

Membrane inositol phospholipids are mediators of hormone and neurotransmitter action

(se f.eks. insulin signallering, PIP2 og PIP3)

Question 32

How do chylomicrons in entereocytes within the small intestine enter the exogenous lipoprotein pathway?

Answer 32

Via the lymph system

TAG is hydrolysed by lipoprotein lipase, found on the surface of endothelial cells lining capillaries.

Question 33

Where is VLDL synthesised?

Answer 33

In the liver.
Metabolised to LDL

Question 34

What are the carriers of TAG?

Answer 34

Chylomicrons and VLDL

Question 35

What transports cholesterol?

Answer 35

LDL and HDL

Question 36

Which two fatty acids are essentiel and why?

Answer 36

Linoleic acid and alpha-linolenic acid cannot be synthesised by animal cells and are therefore essentiel.
They give rise to the n-6 and n-3 polyunsatturated fatty acids through desaturases and elongases

Question 37

Mention the type of sterols in animals and plants

Answer 37

Animal sterol: Cholesterol
Plant sterol: Phytosterol

Question 38

What is the function of the citrate shuttle?

Answer 38

The citrate shuttle transports acetyl-CoA via Citrate across the inner mitochondrial membrane (both ways)
Important for the fatty acid synthesis in the cytosol