Lab 9 - Lipids Flashcards

1
Q

Solubility of lipids

A

Insoluble in water, soluble in fat solvents

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2
Q

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

A

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.
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3
Q

How can simple esters be transferred in the organism?

A

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.

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4
Q

Common unsaturated FA

A

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

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5
Q

Where is cholesterol synthesized?

A

Liver

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6
Q

Function of cholesterol as lipid

A
  • Precursor of steroid hormones and bile acids.

- Constituent of bio. membranes.

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7
Q

Function and example of phosphatides as lipids

A
  • Membrane constituents

- E.g. Lecithin

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8
Q

How is long chain FA transported?

A

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

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9
Q

How can a long chain FA be detached?

A

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

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10
Q

How does quantitative estimation of FFA work?

A

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.

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11
Q

Copper II reagent

A

Triethanol amine, acetic acid and copper sulphate solution

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12
Q

Materials in “quantitative estimation of FFA”

A
  • Copper(II) reagent
  • Na-diethyldithiocarbamate
  • Chloroform
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13
Q

How is cholesterol transported in the organism?

A

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).

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14
Q

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

A
  • 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.
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15
Q

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

A
  • Blood plasma
  • FeCl3 solution: FeCl3 dissolved in glacial acetic acid
  • Colour reagent: FeCl3 with conc. sulphuric acid
  • Glacial acetic acid
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16
Q

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

A
  • Hyperlipidaemia
  • Some hepatic diseases (hepatopathies)
  • Hyperadrenocorticism
  • Hypothyreosis
17
Q

Normal amount of total cholesterol in:

  1. dogs
  2. cats
  3. herbiivores
A
  1. dogs: 2,5-8 mmol/l
  2. cats: 2-6.5 mmol/l
  3. herbivores: 1,5-5 mmol/l
18
Q

How are triglycerides transported?

A

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

19
Q

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

A
  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.
20
Q

Function of glycerol-3-phosphate oxidase (GPO)

A

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

21
Q

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

A

The red quinone derivate can be measured by spectrophotometry.

22
Q

Materials in “measuring triglycerides conc. in blood”

A
  • Blood plasma
  • Colour reagent: enzymes and colour forming substrates (4-aminoantipyrine and phenol) dissolved in phosphate buffer.
  • Standard triglyceride sol.
23
Q

How is prim. bilde acids prod.?

A

During degradation of cholesterol in the liver.

24
Q

Primary bile acids?

A

Cholic acid and chenodeoxycholic acid

25
Q

How is bile acids excreted?

A

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

26
Q

Role of bile acids?

A

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

27
Q

Principle method for determination of cholic acid from bile?

A
  • 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.
28
Q

Materials in “determination of cholic acid from bile”?

A
  • Bile
  • Sucrose sol.
  • Conc.sulphuric acid
29
Q

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

A

-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.

30
Q

What happens at the same time as lipid mobilization?

A
  • 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.
31
Q

Example of ketone bodies

A

Acetone, acetoacetate, beta-hydroxybutirate

32
Q

Where are ketone bodies released and how are they used?

A

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

33
Q

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

A

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

34
Q
  1. Hyperketonaemia
  2. Keonuria
  3. Ketolactia
A
  1. KB in blood
  2. KB in urine
  3. KB in milk
35
Q

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

A

Milk : blood : urine = 1 : 5 : 10

36
Q

Principle method in detection of ketone bodies from urine and milk

A

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