Animal nutrition - lipids Flashcards
describe what lipids are in general
Lipids are heterogeneous organic compounds.
are at least two-component biomolecules (alcohol component + fatty acids), and as a rule, are esters.
– soluble in nonpolar organic solvents (ether, benzene, chloroform)
– not soluble in aqueous solutions
Alcohol groups found in lipids (3)
– glycerol - trivalent alcohol, is in triglycerides
– sphingosine – alcohol backbone of sphingolipids
– cholesterol - unsaturated cyclic alcohol
Classification of fatty acids based on (5)
- Chain length
- Presence of double bonds and their number
- Conjugated FAs
- Branched-chain FAs
- Geometric position of H-atoms near the double bonds can be identified as two isomers
a fatty acid chain length of 4-10 C is calssified as
shortchain FA
a fatty acid chain length of 12-16 C is classified as
medium chain FA
a fatty acid chain length of >17 C is classified as
long chain FA
C atoms in FAs are linked to each other either by
saturated single- or unsaturated double bonds
saturated FAs are more stable tha unsaturated FAs.
▪ one (monounsaturated FA - MUFA) or
▪ several double bonds (polyunsaturated FA - PUFA)
if two double bonds are spaced at least two C atoms away from each other in a FA, it is classified as
Conjugated
branched-chain FAs are classified -iso when
the branch point is on the penultimate carbon (one from the end)
branched-chain FAs are classified -anteiso when
the branch point is on the ante-penultimate carbon atom (two from the end)
Lipids: Geometric position of H-atoms near the double bonds can be identified by two isomers called:
– cis isomer (H one side)
– trans isomer (H mutually)
the longer the carbon skeleton of the saturated FAs,
the higher
the melting point
meaning long saturated FAs (no double-bonds) tend to be solid at room temperature
e.g. coconut oil has 12-carbon atoms, is saturated and its melting point is 24’C
the longer the carbon skeleton of the unsaturated FAs, and the greater the number of double bonds in the carbon skeleton, the
the lower the melting point of the FA
tendecy to be liquid at room temp.
Stearic acid c-skeleton length and melting point
stearic acid carbon skeleton is 18:0
(2nd number denotes number of double bonds)
and melting point is 70’C so is solid at room temp.
Oleic acid c-skeleton length and melting point
oleic acid carbon skeleton is 18:1
(the one denotes there being 1 double bond in the molecule, is called a monounsaturated FA)
the melting point is 13’C so is typically solid at room temperature.
Classification of LIPIDS first and foremost divided into:
Glycerol-containing lipids &
Non-glyceride lipids
Non-glyceride lipids include (5)
Cerebrosides
Eicosanoides
Steroids
Terpenes
Waxes
Glycerol-containing lipids are divided into:
simple & complex lipids
simple lipids are also known as
fats
such as triacylglycerols
complex lipid division (2)
divided into glycolipids and phospholipids
glycolipid division (2)
glycolipids and galactolipids
phospholipid division (2)
lecithin and cephalin
Simple lipids or fats occur mainly in
feeds and in animal body as triglycerides or neutral fats
Triglycerides are composed of
one molecule of glycerol and usually three FA residues
In feeds and in the animal body di- and monoglycerides are also present, but these are mainly metabolic residues of triglycerides
Phospholipids consist of
Glycerol molecule + 2 FA residues and
phosphoric acid + proteinaceous compound
lecithin is
is a phospholipid
a yellowish-brownish fatty substance, in plant and animal cell
membranes, egg yolk, dietary supplement
lecithin consists of
Lecithins are composed of phosphoric acid, cholines (B4), esters of glycerol, and two fatty acids.
Cephalin is a
phospholipid found in brain tissue and nerves
it consists of a combination of glycerol esterified with two fatty acids and phosphoric acid.
the phosphate group is combined with the ethanolamine in Cephalin.
Glycolipids usually consist of
glycerol + 2 FA + sugar residue
they contain Galactolipids because within the sugar residue is
one or two galactose molecules bound to the first carbon atom of the glycerol
Glycolipids are mainly in
plant origin feeds
in grasses, but also in clover
Main glycolipid present in the animal body is
cerebroside (alcohol backbone is sphingosine), which occurs mainly in the brain neural tissue
Cholesterol is
is the major sterol in animal body and is an essential component of cell membranes.
- … is a precursor of all steroids present in organism
- … content is high in animal fats, egg yolk, brain tissue, blood plasma -> lipoproteins
- … is synthesised in liver, but to a small extent also in the mucosa of the small intestine, adrenal gland, ovary, testis and placenta
- …chemically an alcohol, but in contrast to alcohols does not dissolve in water
In plants, the most intense fat hydrolysis takes place in
the germinating seeds of oil crops.
The pH optimum for lipases
in plants?
in small intestine of animals?
– in plants 4.7-5.0
– in the small intestine of animals 7.0-8.8
Lipids are digested in the rumen by
microbial lipases.
Lipids are digested in the rumen by microbial lipases are hydrolyzed into?
into glycerol (produces also sugars) and free fatty acids
what is the fate of the glycerol produced from microbial hydrolysis of lipids?
glycerol (but also sugar) is consumed by microorganisms for the production of ATP
where are fatty acids absorbed in ruminants?
In the small intestine the FAs are absorbed in the same way as in monogastric animals.
In monogastric animals the hydrolysis of fat begins where by what action of what
in the duodenum by the emulsifying action of bile
(bile acids and their salts) and pancreatic lipase
Lipase splits triglycerides into
2-monoglyceride (2-MG) and two FAs
– small amount of 2-MG degrades into glycerol and FA
Water soluble compounds (glycerol, choline) absorbed…?
directly into the blood.
Short-chain FAs (C4-C10) are easily absorbed into
the cells of the small intestine, after which they are readily hydrolysed to produce ATP,
which is why they are not found, or their content is very low, in fat deposits (also in milk fat).
mixed micelles are
water soluble complexes, composed of phospholipids and bile salts
either 2-monoglycerides (mostly in monogastrics) or free FAs (mostly in Ru) form mixed micelles, with the help of bile acids, cholesterol and phospholipids (lecithin)
Mixed micelles pass through what on the surface of pillar-shaped intestinal epithelial cells in order to enter into them
they pass through the fixed water and mucous layer on the surface of pillar-shaped intestinal epithelial cells
What happens to mixed micells after entering the intestinal epithelial cells
the mixed micelles are decomposed into components
What must be formed before insoluable triglycerides can enter into the internal circulation of the organism?
lipoproteins (chylomicrons)
Lipoproteins are
the main transport molecules of triglycerides, which are synthesized in the small intestine epithelial cells (i.e. chylomicrons) or in the liver
apo(lipo)proteins are
are proteins that bind lipids
are mainly produced in the liver, except Apo B-48, which is produced in the epithelial cells of the small intestine from absorbed AAs
function of low density lipoproteins
cholesterol transport INTO tissues
function of high density lipoproteins
cholesterol transport OUT of tissues
in tissues the lipoproteins are digested by
lipoprotein lipase and triglycerides are released
▪ if the animal is growing, the free FAs in the adipose tissue and in the udder are transferred respectively into the composition of depot fat and milk fat
▪ skeletal and cardiac muscle use FAs for ATP energy production
what is the catabolic process by which fatty acid molecules are broken down to generate acetyl-CoA and NADH and FADH2, which are used in the electron transport chain for ATP production?
Fatty acids can be used to produce ATP during β-oxidation
β-oxidation can be used on Fatty acids to generate what (3)
acetyl-CoA
NADH and
FADH2
which are used in the electron transport chain for ATP production.
Fate of glycerol in the body
either used to produce ATP in conjunction with CO2 and H2O
or
resynthesis of triglycerides or glucose in gluconeogenesis (ATP required for anabolism)
Fate of free fatty acids in teh body
beta oxidation in mitochondria to produce ATP (and CO2 and H2O)
or
resynthesis of triglycerides (ATP required for anabolism)
Lipoproteins from which triglycerides are degraded are called
remnant lipoproteins
Remnant lipoproteins contain
protein, phospholipids and cholesterol
Fate of Remnant lipoproteins
can either be degraded in the liver
or
used for the synthesis of new lipoproteins in the liver
Biohydrogenation of unsaturated FAs means
is a process that occurs in the rumen in which bacteria convert unsaturated fatty acids (USFA) to saturated fatty acids (SFA) and as a consequence, the fatty acids leaving the rumen are mostly highly saturated.
Unsaturated FAs released by microbial lipases from triglycerides are toxic to (cellulolytic) bacteria, and are therefore subjected to
biohydrogenation
The toxicity of unsaturated FAs to cellulolytic bacteria can be seen in the (3)
– decrease in the digestibility of cellulose
– prolongs retention time of the cellulose material in the rumen
– which in turn causes a reduction in feed intake and milk production
Step 1 of the Biohydrogenation of unsaturated FAs
- step 1 – isomerisation of unsaturated FAs
double bond from cis-orientation to trans-orientation
Step 2 of Biohydrogenation of unsaturated FAs
- step 2 – saturation of isomerised FAs
What does CLA do for the body?
Conjugated linoleic acid might help reduce body fat deposits and improve immune function.
The degree and the rate of biohydrogenation depends on
the number of double bonds in the FA C-skeleton
– the more double bonds there are in the C-skeleton the FASTER and more completely is the FA biohydrogenation
Free unsaturated FAs are biohydrogenated within the range of
70…100%:
– linoleic acid (C18:2) 70…95 %
– α-linolenic acid (C18:3) 85…100 %
A high amount of concentrate and UFAs in the feed ration significantly decreases
biohydrogenation (shifts down) ->
milk fat depression (content decreases)
If in the ration DM, the amount of starch & sugars exceeds ?,
milk fat % decreases.
If in the ration DM the amount of starch+sugars exceeds 300 g/kg
milk fat % decreases.
If in the ration DM, the amount unsaturated FA’s exceeds ?, milk fat % decreases.
If in the ration DM, the unsaturated FA’s exceeds 25 g/kg milk fat % decreases.
De novo synthesis of FAs takes place in
the cell cytoplasm:
– mainly in the liver and the lactating udder
– but also in adipose tissue and the kidneys
De novo synthesis of FAs is
the repeated inclusion of acetyl-CoA or activated acetic acid
(beta-hydroxybutyrate acid (BHBA) in the udder)
into the new FA chain-lengthening
Where does Acetyl-CoA originates from in humans, rat, pig
glucose catabolism
Where does Acetyl-CoA originates from in rabbits
glucose catabolism and activation of acetic acid
Where does Acetyl-CoA originates from in bovine
from activation of acetic acid
specific protein B-48 is what
ApoB-48 is an apolipoprotein specific to a lipoprotein, chylomicron (CM) which is formed in intestine and carries exogenous lipids derived from foods to the liver and peripheral tissues.
Saturated fatty acids are more stable than unsaturated fatty acids
A. Right
B. Wrong
A. Right
The longer the C-skeleton of saturated FAs, the lower is their melting point
A. Right
B. Wrong
B. Wrong, it would be HIGHER
The longer the C-skeleton of UNsaturated FAs, the lower is their melting point
A. Right
B. Wrong
B. Wrong
Lecithin’s proteinaceous compound is …
A. choline
B. ethanolamine
A. choline
Which of these oils is in solid form at room temperature?
A. Corn oil
B. Groundnut oil
C. Coconut oil
D. Soybean oil
C. Coconut oil
Triglycerides are digested in the rumen into …
A. glycerol and three fatty acids
B. glycerol and fatty acids and then further into carbon dioxide and water
C. Are not digested at all
A. glycerol and three fatty acids
During re-synthesis of triglycerides the ATP energy …
A. is produced
B. is used
B. is used
Which bacteria take part in the biohydrogenation process?
A. amylolytic
B. cellulolytic
C. saccharolytic
B. cellulolytic
Reduction in milk fat content is caused by …
A. high amounts of ruminally degraded starch in the ration
B. high amounts of polyunsaturated fatty acids in the ration
C. both
C. both
To synthesise fatty acids in the udder of cattle the necessary activated acetic acid originates from
A. glucose catabolism
B. acetic acid
C. both
B. acetic acid
beta oxidation produces what intermediate that goes where?
β-oxidation is the catabolic process by which fatty acid molecules are broken down in the mitochondria in eukaryotes to generate acetyl-CoA, which enters the citric acid cycle, and NADH and FADH2, which are co-enzymes used in the electron transport chain
