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Biochemistry > Lipids > Flashcards

Lipids Flashcards

1
Q

Major dietary lipids

A

Triacylglycerol,
cholesterol
Phospholipids
Indian diet 20-30 g per day , western 2 or 3 times more

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2
Q

What is beta-oxidation

A

Fatty acids are rich in energy , energy is released when fatty acids undergo beta-oxidation .
*Oxidation and splitting of two carbon units occur at the beta-carbon atom .
* two carbon atoms are sequentially removed from carboxylic end of fatty acids

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3
Q

Preparation steps for beta oxidation

A
  1. Activation of fatty acids
  2. Role of carnitine
  3. Carnitine Acyl Transferase
  4. Translocase
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4
Q

What’s coenzyme A

A

Complex molecule containing B complex vitamin pantothenic acid and a molecule of beta mercapto ethanolamine, this SH group forms thioester bond in acyl CoA

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5
Q

The activation of fatty acids
Site
Enzyme

A

Activated to their CoA derivative
Takes place in cytoplasm
Enzyme is thiokinase or fatty acyl CoA synthetase
Three different enzymes (one each for short , medium , long chain FA)

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6
Q

In preparative step 1 ,small chain fatty acids may be activated by

A

Thiophorase enzyme, using succinyl CoA

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7
Q

What is carnitine and where is it synthesised

A

Beta hydroxy-gamma -trimethyl ammonium butyrate .
Synthesised from lysine and methionine in liver and kidney

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8
Q

Where does beta oxidation take place

A

Mitochondria

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9
Q

What is the role in carnitine in beta oxidation

A

Transporter involved in the transfer of fatty acids .
From cytoplasm to mitochondria becoz long chain fatty acyl CoA cannot pass thro inner mitochondrial membrane

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10
Q

What is the third preparative step

A

Enzyme carnitine acyl transferase-I (CAT-I) will transfer the fatty acyl group to the hydroxyl group of carnitine to form acyl carnitine.
Occurs on cytosolic side of inner mitochondrial membrane

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11
Q

What will carry the acyl carnitine across the membrane to the matrix of mitochondria

A

A protein translocase

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12
Q

Gastric lipase is secreted by what and activated by what

A

Secreted by chief cells
Stimulated by gastrin

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13
Q

Classification of glycolipids

A

Two types based on type of carbohydrate residues
1. Cerebrosides- contain glucose or galactose as residues
Kerasin, cerebron , nervon, oxynervon
2. Gangliosides xcontain complex oligosaccharides as carbohydrate residue
GM1 ,2 ,3 ,4

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14
Q

Chemical name of lecithin

A

Phosphatidyl choline

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15
Q

Lipoprotein involved in reverse cholesterol synthesis

A

LDL

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16
Q

Name two polyunsaturated fatty acids

A

Linoleic , alpha-linolenic acid
Arachidonic acid

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17
Q

Enzyme deficient in Niemann Pick disease

A

shingomyelinase

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18
Q

Site of oxidation of very long chain fatty acids

A

Peroxisomes

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19
Q

Name the rate limiting step in fatty acid synthesis

A

Acetyl CoA carboxylase

20
Q

Glucose -alanine cycle is also known as

A

Cahill cycle

21
Q

Hormonal regulation of gluconeogenesis

A

Glucagon & Glucocorticoids increase gluconeogenesis.
Glucocorticoids induce synthesis of hepatic amino transferases ( substrate for gluconeogenesis)
$$$

22
Q

Glucogenic amino acids

A

Alanine, glutamic acid ,aspartiic acid

23
Q

Rapaport Leubering cycle

A

In erythrocytes

24
Q

Pasteur effect

A

Under aerobic conditions, glycolysis is inhibited .
Inhibitory effect of oxygen on glycolysis is

25
Q

Cori’s cycle or lactic acid cycle

A

*Process in which glucose is converted to lactate in the muscle , liver reconverts it into glucose .
*actively contracting muscle , pyruvate reduced to lactic acid (accumulates in the muscle )
Prevent lactate accumulation, body utilizes Cori’s cycle
*

26
Q

Significance of Cori’s cycle

A
27
Q

Define lipids

A

Heterogeneous group of compounds of biochemical importance that are insoluble in water . Freely soluble in non-polar organic solvents (benzene , chloroform, ether , hot Alcohol , acetone )

28
Q

Site of beta-oxidation in tissues and in the cell

A

Tissue site : liver , muscle , renal cortex ,adrenal medulla , heart
In cell : mitochondria

29
Q

Energetic of beta oxidation

A

8 acetyl CoA * 10 = 80 ATP
7 FADH2 × 1.5 = 10.5 ATP
7 NADH × 2.5 = 17.5 ATP
Gross total = 108 ATP
Net yield = 108 minus 2=106 ATP

30
Q

Steps in the beta oxidation

A

Fatty acyl CoA —-> alpha, beta unsaturated acyl CoA
——> beta hydroxy acyl CoA ——> beta keto acyl coA

31
Q

Classification of lipids based on chemical nature

A

Simple lipids
Compound lipids
Derived lipids
Lipids complexed to other compounds

32
Q

The types and examples of non- phosphorylated lipids

A
  1. Glycosphingolipids cerebrosides (ceramide monohexosides)
    Globosides ( ceramide oligosaccharides )
    Gangliosides ( ceramide + oligosaccharides + n acetyl neuraminic acid )
  2. Sulfolipids or sulfatides
    Sulfated cerebrosides
    Globosides
    Gangliosides
33
Q

Non- nitrogen containing phospholipids

A

Phosphatidylinositol
Phosphatidylglycerol
Diphosphatidylglycerol (cardiolipin)

34
Q

Clinical significance of PUFA

A
  1. Linoleic and linolenic acids are
  2. Called essential , not synthesized by the body , supplied in the diet
  3. Arachidonic acid = precursor of prostaglandins.
    Ar.acid can be synthesized if essential fatty acid is supplied in diet
  4. Penta-enoic acid in fish oils , great nutritional importance (omega 3 unsaturated fatty acid )
    5.eicosanoids (eicosa = 20)
    Derived from 20 C arachidonic acid .
    Poly-enoic FA .
    They are prostanoids (prostaglandins, prostacyclins , thromboxanes)
    And leukotrienes
  5. UFA designated as
    Omega 3 family -linolenic acids
    Omega 6 - linoleic and arachidonic acids
    Omega 9 - oleic acid
35
Q

Configuration of PUFA in naturally occurring lipids

A

Cis configuration

36
Q

Clinical and epidemiological positive roles of omega 3 fatty acids

A
  1. Infant development
  2. Cancer
  3. CV diseases
  4. Mental illnesses- depression, ADHD , dementia
  5. Pleiotropic effects - effects against inflammation, platelet aggregation, hypertension , hyperlipidemia
    Beneficial effects mediated through several distinct mech - including alteration in cell membrane composition and function , gene expression or eicosanoid production
37
Q

Oils with large percentage of PUFA

A

safflower oil (79%)
Sunflower oil (64%)
Corn oil (62%)
Fish oil (57%)
Cotton seed oil (55%)

38
Q

Oils with low % of PUFA

A

Coconut oil (2%) (SFA = 86%)
Butter (5%)
Ox (tallow ) 5%
Palm oil (6%)

39
Q

Saponification

A

1.Triacylglycerols hydrolyzed by alkali - process is known as .
Products are glycerol and soaps
2. Saponification number -no.of milligrams of KOH required to saponify one gram of fat
3. Indication of mol.weight of fat . Inversely proportional to it
4.human fat = 194-198
Butter = 210-230
Coconut oil = 253 -262

40
Q

Iodine number of fat

A

1.Defined as the number of grams of iodine taken up by 100 grams of fat .
2. Index of degree of unsaturation , directly proportional to the content of UFA
3. Higher the iodine , higher the degree of unsaturation
4. Of butter is 28
Sunflower oil 130

41
Q

Mustard oil (rapeseed oil )contains

A

Erucic acid

42
Q

Rancidity of fat

A

*Fats and oils tendency to become rancid
* rancid it’s refers to appearance of unpleasant smell and taste for fats and oils
*

43
Q

Hydrolysis rancidity

A
44
Q

Cephalin

A

*Phosphatidylethanolamine
* differs from lecithin , N base ethanolamine instead of choline
* found in bio membrane and possess amphipathic properties

45
Q

Precursor of Prostaglandins
And enzyme used for conversion
And inhibitor

A

Arachidonic acid
Enzyme : cyclo-oxygenase
Inhibitor: aspirin

46
Q

Two types of rancidity

A

Hydrolytic, oxidative

47
Q

What is a prostaglandin

A

Example of derived lipid
Metabolic regulator lipid
Present in all tissues , but originally isolated from prostate tissue
Most potent biologically active substance

Biochemistry (10 decks)

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