Lab 9 - Lipids

Question 1

Solubility of lipids

Answer 1

Insoluble in water, soluble in fat solvents

Question 2

How does the lipids differ from each other, and what kind of groups of lipids do we have?

Answer 2

In chem. structure.

1. Simple: esters of FA with glycerol. Gen. found in organisms as triacylglycerols. Saturated or unsaturated. Function: E storage.
2. Derivated lipids - lipoids: Cholesterol is important. Phosphatides also.

Question 3

How can simple esters be transferred in the organism?

Answer 3

By the blood circ. to the fat tissue to be stored as dipot fat, or transported from the dipot to the user organs in form of free FA.

Question 4

Common unsaturated FA

Answer 4

Oleic acids. In plants high proportion of more unsaturated FA is common (linoleic, linolenic acids)

Question 5

Where is cholesterol synthesized?

Answer 5

Liver

Question 6

Function of cholesterol as lipid

Answer 6

• Precursor of steroid hormones and bile acids.

- Constituent of bio. membranes.

Question 7

Function and example of phosphatides as lipids

Answer 7

• Membrane constituents

- E.g. Lecithin

Question 8

How is long chain FA transported?

Answer 8

From fat depot to the user organs (muscle, liver) by the blood. Bound to albumin with sec.bonds.

Question 9

How can a long chain FA be detached?

Answer 9

By Cu(II)sulphate/CuSO4 or Cu(II)nitrate/Cu(NO3)2 from the albumin. The produced copper salt can be dissolved in chloroform.

Question 10

How does quantitative estimation of FFA work?

Answer 10

After detaching FA from albumin with Cu(II)-reagent:

The nr. of Cu2+ in the chloroform is the same nr. as FA, and can be measured by diethyldithiocarbamate by photometry.

Question 11

Copper II reagent

Answer 11

Triethanol amine, acetic acid and copper sulphate solution

Question 12

Materials in “quantitative estimation of FFA”

Answer 12

• Copper(II) reagent
• Na-diethyldithiocarbamate
• Chloroform

Question 13

How is cholesterol transported in the organism?

Answer 13

Fro the site of synthesis (liver, intestinal wall, gonades) to user tissue while bound to albumin. Can be transported either in free or esterified form (by FA).

Question 14

What is the principle method for measuring the totalt cholesterol conc. of the blood plasma?

Answer 14

• In presence of glacial acetic acid and sulphuric acid, FeCl3 will oxidize cholesterol and form new unsaturated double bonds.
• Two of these oxidized cholesterol molecules are able to bind to each other and prod. conjugated double bonds –> purple color.
• The intensity of the color can be measured with spectophotometry.

Question 15

Materials in “measuring the cholesterol conc. of the blood”?

Answer 15

• Blood plasma
• FeCl3 solution: FeCl3 dissolved in glacial acetic acid
• Colour reagent: FeCl3 with conc. sulphuric acid
• Glacial acetic acid

Question 16

Which diseases can be diagnosised with help from measuring cholesterol level?

Answer 16

• Hyperlipidaemia
• Some hepatic diseases (hepatopathies)
• Hyperadrenocorticism
• Hypothyreosis

Question 17

Normal amount of total cholesterol in:

1. dogs
2. cats
3. herbiivores

Answer 17

1. dogs: 2,5-8 mmol/l
2. cats: 2-6.5 mmol/l
3. herbivores: 1,5-5 mmol/l

Question 18

How are triglycerides transported?

Answer 18

In chylomicrons and diff. types of lipoproteins (VLDL, LDL, IDL, HDL) in the blood plasma.

Question 19

Which enzymatic reactions is used to measure triglycerides conc. in blood plasma?

Answer 19

1. Triglycerides transported in lioproteins are hydrolysed to glycerol and FA by lipoprotein lipase.
2. Glycerol kinase enzyme converts glycerol to glycerol-3-P by using one ATP molecule.
3. Glycerol-3-phosphate oxidase (GPO) oxidizes glycerol-3-P to dihydroxyacetonephosphate. At the same time H2O2 is released, by using O2 from air.
4. The prod. H2O2 is converted to water by peroxidase enzyme (POD), while a red quinone derivate is prod.

Question 20

Function of glycerol-3-phosphate oxidase (GPO)

Answer 20

Group of aerobe dehydrogenases. The prod. FADH2 passed the hydrogens directly to oxygen of the air, and H2O2 is released.

Question 21

How can we measure the triglycerides conc. after the enzymatic reactions?

Answer 21

The red quinone derivate can be measured by spectrophotometry.

Question 22

Materials in “measuring triglycerides conc. in blood”

Answer 22

• Blood plasma
• Colour reagent: enzymes and colour forming substrates (4-aminoantipyrine and phenol) dissolved in phosphate buffer.
• Standard triglyceride sol.

Question 23

How is prim. bilde acids prod.?

Answer 23

During degradation of cholesterol in the liver.

Question 24

Primary bile acids?

Answer 24

Cholic acid and chenodeoxycholic acid

Question 25

How is bile acids excreted?

Answer 25

Their salts with taurine and glycine are excreted in the bile, and get into the small intestine.

Question 26

Role of bile acids?

Answer 26

Have detergent effects; play role in digestion and absorption of lipids.

Question 27

Principle method for determination of cholic acid from bile?

Answer 27

- Taurocholic acid and glycocholic acid will be determined. - Sucrose is turned into hydroxymethyl furfural by conc. sulphuric acid. - Oxymethyl furfural prod. a coloured complex with cholic acid.

Question 28

Materials in "determination of cholic acid from bile"?

Answer 28

- Bile - Sucrose sol. - Conc.sulphuric acid

Question 29

How is the E gain in lactation in dairy cows covered by?

Answer 29

-Lipid mobilization from the fat depots; lipolysis is incr. in the adipose tissue, where FFA are released into the blood and taken up by the liver. In the liver they enter beta-oxidation.

Question 30

What happens at the same time as lipid mobilization?

Answer 30

- GNG in hepatocytes prod. a huge amount of glucose for lactose synthesis, so OAC also enters GNG. - The high amount of Ac-CoA prod. in beta-ox. can´t enter citrate cycle because of lack of OAC, so they enter ketogenesis. - Therefore hepatocytes prod. high amount of KB.

Question 31

Example of ketone bodies

Answer 31

Acetone, acetoacetate, beta-hydroxybutirate

Question 32

Where are ketone bodies released and how are they used?

Answer 32

Released in blood stream and utilized by extrahepatic tissues in ketolysis.

Question 33

What happens in dairy cows in beginning and peak of lactation?

Answer 33

Ketogenesis is so intensive that the whole amount of the prod. KB can´t be broken down in ketolysis, therefor KB accumulate in blood and will be excreted by urine and milk --> ketosis disease develops

Question 34

1. Hyperketonaemia 2. Keonuria 3. Ketolactia

Answer 34

1. KB in blood 2. KB in urine 3. KB in milk

Question 35

Proportion of ketone body conc. in diff. bio. fluids?

Answer 35

Milk : blood : urine = 1 : 5 : 10

Question 36

Principle method in detection of ketone bodies from urine and milk

Answer 36

Sodium nitroprusside forms a purple coloured complex with acetoacetate and acetone in the presence of ammonia.