Lipids Flashcards
What are lipids
- ether extract in proximate analysis
- organic compounds ( insoluble in water and soluble in organic compounds such as ether and chloroform)
- important in biochemical, physiological functions of an animal ( dietary sources of energy, constituent of cell membranes= phospholipids, fat-soluble vitamins, corticosteroid hormones, mediators of electron transport)
why do lipids have 2.25X more energy
- contain more C and H in relation to O
- a more concentrated source of energy = requires more oxygen, to oxidize products
what are some simple lipids
- fatty acids
- triacylglycerols, diacylglycerols, monocylglycerols
- waxes = sterol esters (for lipid compounds not energy) non-sterol esters
what are waxes used for
- functional starting point to build onto other molecules
- not used for energy
what are compound lipids
- phospholipids = phosphatidic acids, plasmalogens and sphingomyelins
- glycolipids = lipids concentrated around a carbohydrate
- lipoprotiens = lipid absorbtion in small intestine, transport of lipid molecules into the blood stream
what is the difference between unsaturated and saturated fatty acids
- saturated do not have double bonds
- unsaturdated have double bonds
what is the difference between a CIS and TRANS configuration
- CIS = H on the second C is upwards
- TRANS = H on the second carbon is facing down
what are some naturally occuring FAs in the CIS configuation
- ruminant fats
- partial hydrogenation ( solidify vegetable oils at room temp.
what are important saturdated fatty acids in the diet
16:0
18:0
what are important unsaturdated fatty acids in the diet
18:1 (n-9)
18:2 (n-6)
18:3 (n-3)
what are the two essential fatty acids in the body
- linoleic acid (c18:2n-6) or C18: 2 triangle 9,12
- a-linolenic acid (C18 : 3n-3) or c18: 3 triangle 3,6,9
what do animals lack?
- triangle 12 and triangle 15 desaturase enzymes
- have desaturase activity
what is linoleic acid used for
- dietary supply of EFA
- arachidonic acid synthesis
what are symptoms of essential fatty acid deficiency?
- retarded growth
- kidney lesions
- dermatitis of back and feet
- necrosis of tail
- reproductive failure
- early death
what does omega 3 and 6 contribute too
- physiological functions = brain development, anti-carcinogenic and anti-atherosclerosis
what is said to happen with an over production of omega 3 and 6
- excessive amounts of omega 6 is linked to cancer and heart disease
- but together they have positive effects on cardiovascular disease and cancer
what is the lipid content of plants
- relatively low, except oilseeds
what is the lipid concentration of animal tissues
- relatively large amounts in animal tissues = in adipose tissues, major energy source
- amount is variable = diet, age and physiological state
what is the difference between a dry and lactating animal with adipose tissue storage
- a dry animal will have a higher adipose tissue because a lactating animal uses lipid storage for milk production
what are major functions of fatty acids/ lipids in the body
- long-term energy reserves
- insulation
- a structural component of the cell membranes
- component of enzyme systems
- component of steroid hormones
- fat-soluble vitamin absorption, synthesis
what is a fat
- solid at room temperature
- longer chain 18-20 no C=C bonds
- saturated
what is an oil
- liquid at room temperature
- 12,14, 16, shorter chains
- double bonds
- unsaturated
what is esterfied
- fatty acid attached to glycerole back bone
what is non esterfied
- free fatty acids that is no longer attached to the back bone
what is a phospholipid
- polar head group contianing N base
- phosphate group
- contains hydrophobic and hydrophilic end
- provides structure
- allows for selective permeability of the membrane through lipid bylayer
- lipid transport as part of lipoprotiens
what is a lipoprotein
- hydrophobic core
hydrophilic surface monolayer - lipid transport in blood
- single layer not lipid bilayer
what is a glycolipid
- glucose and galactose ( FA, N base)
- structural role in cells
- cerebrosides, gangliosides found predominantly in the brain and medullary shealths of nerve tissue
where do animals usually get glypolipids
- from grasses and other forages that are rich in glycolipids
what are sterols/steroids
- cholesterole in free form
- 4 ring structure
- important building block in moderation
- precursor for vitamin D synthesis
what is the role of fat in fat-soluable vitamin nutrition
- mixed micelles formed during absorbtion of fatty acids contain fat soluable vitamins (retinol Vit A, Vit D Vit E and Vit K)
what is the difference between lipid based synthesis in animals vs plants
animals - highly saturdated
plants - highly unsaturated
where are the different type of lipids found
- tryglycerides = cereal grains, oilseeds and animal fats
- glycolipids = forages (4-6%) of DM is lipid
- phospholipids = high in ruminal bacteria
what is the carbon count in different fatty acids
- short chain fatty acids = up to 8 chains
- medium chain fatty acids = 10-16 carbons
- long chain fatty acids = equal to or greater then 18 carbons
what is the digestibility of fats and oils
- most fats, oils are highly digestible
- digestibility is affected by the degree of saturation (unsaturdated are more digestible)
- increasinf chain length increases digestibility
why does saturated lipids have low digestibility
- there is no kinks without c=c so they pack tighter together and dont allow enzymes to penetrate
why do unsaturated lipids have a higher digestibility
- as the degree of double bonds goes up, the kinks increase and they are more easily broken down
why are lipids added to livestock diets
- provide energy
- increase palatibility
- provide fat-soluable vitamins
- provide essential fatty acids
- alleviate heat stress
- dust control
- lubrication
- improve diet handling
how does putting lipids in teh diet help to alleviate heat stress
- ## it creates a low heat increment = increasing the feed intake
how does adding lipids reduce dust
- increases palatability
- improve air quality
what is the usual lipid concentration in diets? what % is supplimented
- 2-4%
- adding 3-5% brings it up to 6-7%
where is the location of lipid digestion
- primarily in the small intestine
- lingusl lipase(serous gland) and gastric lipase (stomach wall) will also play a minor role
how does the stomach initiate emulsification
- produced with salivia, small breakdown because its not in th mouth very long
- cheif cells in stomach wall release gastric lipase for emulsification
- muscle contractions begin emulsification
what are the phases of lipid digestion
- emulsification (large fat globules into tiny droplets )
- hydrolysis
- micelle formation
- absorbtion
what is the role of bile salts
- created in the liver, stored in the gallbladder
- facilitates emulsification
- reabsorbed through the ileum
what is the role of co-lipase
- knocks off teh bile salt in order to absorb the fat globule
- products are non esrerfied fatty acids, monoglycerydes, diglycerides and cholesterole
- these combine with bile acids and phosphorus to form micelles
what is the structure of a micelle
- bile salts form the edge of micelle (contains the end products in the core)
- NEFA, monoglycerides, cholesterol, lysophospholipids exist in bilayer inside micelle (hydrophilic end pointed out and interacts with aqueous environment)
micelles interact with microvilli at apical membrae to release contents (are not absorbed) - bile salts reabsorbed in ileum for reuse
- micelles release contents for absorbtion - entrocye the synthesis at endoplasmic reticulum - absorbed by the lymphatic system
chylomicron structure
- transports dietary lipids
90% tryglycerides
4% phospholipid
5% cholesterole
1% protien - released into lymphatic circulation cia exocytosis
- used to transfer dietary lipids
what is the mechanism of absorbtion
- not clearly understood
- passive diffusion
- fatty acid transport proteins (FATP 1-4)
- facilitate absorbtion of fatty acids
- not energy dependednt
how are dietary fats transported
- chylomicrons transport TG to adipose tissues and they are stored as fat
- lipoprotein lipase expressed in adipose tissue hydrolyze TG to NEFA and glycerole
- NEFA are released into the bloodstream and can be used for peripheral tissue for energy and fat synthesis
- glycerole used for energy
sequential B oxidation of oleic acid
- fatty acyl-CoA cleaved to released acetyl CoA = dehydrogenase (removes 2 carbon units)
- complete oxidation of palmitic acid yields 106 moles of atp
what happens if there is an over production of Acetyle CoA
- generally happens during a low carb diet = forces body to break down adipose tissue and it exceeds the TCA cycle requirement
- creates keotene bodies (as an over flow pathway )
- acetoacetate, B hydroybutyrate and acetone
- ketones get ecreated
- creates a smell
what is the function of lipoprotein lipase
- breaks down tryglycerides into 3 fatty acids
- can be used for energy or glucose
- betaoxidation - yeilds ATP for energy
- can also be synthesized to reform other fatty acids
- converted in acetyl coa
- maonyl coa + 2 carbon units in the form of acetly coa synthesis of fatty acids
what is biohydrogenation of free fatty acids
-requires a free COOH group
- addition of 2 H to break c=c and take unsaturated fatty acids to saturdated fatty acids
how does biohydrogenation alter methanogenesis
- methane production in the rumen
- reduce methane production because it uses up hydrogen
- diet high in unsaturdated molecules to cut down methane production
what are key biohydrogenated intermediates
- trans 10 C18:1 (rumenic acid) ; trans 10, cis 12 CLA (anti- liponegic - suppresses in adipose and mammary gland, supress milke fat synthesis)
- trans 11 c18:1 (vaccenic acid) - synthesis of cis-9, trans 11 CLA in adipose tissue - out of rumen into the small intestine - adds c=c
- cis 9 trans 11 CLA = use tissue in mammary glands can synthesis cis 9 trans 11, delta 9 unsatrdated enzyme
what are health benefits of CLA
- reduce blood pressure
- reduce cancer
- gut health
- reduce plack build up
- reduce cholesterole
how much additional lipids can ruminants be fed
- 6-7% maximum of the total diet
what happens if to much fat is added into the diet
- impared rumen function = reduced fiber digestion
- reduced production of VFA’s
- reduces DMI and milk yeild
- milk fat depression - trans fatty acids produced in the rumen, absorbed in the small intestine and inhibit milke fat synthesis
what arethe two mechanisms involved in reduced fibre digestion
- form layer around feed particles (microbes are unable to digest)
- reduce protozoa populations in rumen ( unsaturdated fats are toxic to protozoa)
