Lipids Flashcards
1
Q
What are lipids
A
- 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)
2
Q
why do lipids have 2.25X more energy
A
- contain more C and H in relation to O
- a more concentrated source of energy = requires more oxygen, to oxidize products
3
Q
what are some simple lipids
A
- fatty acids
- triacylglycerols, diacylglycerols, monocylglycerols
- waxes = sterol esters (for lipid compounds not energy) non-sterol esters
4
Q
what are waxes used for
A
- functional starting point to build onto other molecules
- not used for energy
5
Q
what are compound lipids
A
- 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
6
Q
what is the difference between unsaturated and saturated fatty acids
A
- saturated do not have double bonds
- unsaturdated have double bonds
7
Q
what is the difference between a CIS and TRANS configuration
A
- CIS = H on the second C is upwards
- TRANS = H on the second carbon is facing down
8
Q
what are some naturally occuring FAs in the CIS configuation
A
- ruminant fats
- partial hydrogenation ( solidify vegetable oils at room temp.
9
Q
what are important saturdated fatty acids in the diet
A
16:0
18:0
10
Q
what are important unsaturdated fatty acids in the diet
A
18:1 (n-9)
18:2 (n-6)
18:3 (n-3)
11
Q
what are the two essential fatty acids in the body
A
- linoleic acid (c18:2n-6) or C18: 2 triangle 9,12
- a-linolenic acid (C18 : 3n-3) or c18: 3 triangle 3,6,9
12
Q
what do animals lack?
A
- triangle 12 and triangle 15 desaturase enzymes
- have desaturase activity
13
Q
what is linoleic acid used for
A
- dietary supply of EFA
- arachidonic acid synthesis
14
Q
what are symptoms of essential fatty acid deficiency?
A
- retarded growth
- kidney lesions
- dermatitis of back and feet
- necrosis of tail
- reproductive failure
- early death
15
Q
what does omega 3 and 6 contribute too
A
- physiological functions = brain development, anti-carcinogenic and anti-atherosclerosis
16
Q
what is said to happen with an over production of omega 3 and 6
A
- excessive amounts of omega 6 is linked to cancer and heart disease
- but together they have positive effects on cardiovascular disease and cancer
17
Q
what is the lipid content of plants
A
- relatively low, except oilseeds
18
Q
what is the lipid concentration of animal tissues
A
- relatively large amounts in animal tissues = in adipose tissues, major energy source
- amount is variable = diet, age and physiological state
19
Q
what is the difference between a dry and lactating animal with adipose tissue storage
A
- a dry animal will have a higher adipose tissue because a lactating animal uses lipid storage for milk production
20
Q
what are major functions of fatty acids/ lipids in the body
A
- 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
21
Q
what is a fat
A
- solid at room temperature
- longer chain 18-20 no C=C bonds
- saturated
22
Q
what is an oil
A
- liquid at room temperature
- 12,14, 16, shorter chains
- double bonds
- unsaturated
23
Q
what is esterfied
A
- fatty acid attached to glycerole back bone
24
Q
what is non esterfied
A
- free fatty acids that is no longer attached to the back bone
25
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
26
what is a lipoprotein
- hydrophobic core
hydrophilic surface monolayer
- lipid transport in blood
- single layer not lipid bilayer
27
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
28
where do animals usually get glypolipids
- from grasses and other forages that are rich in glycolipids
29
what are sterols/steroids
- cholesterole in free form
- 4 ring structure
- important building block in moderation
- precursor for vitamin D synthesis
30
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)
31
what is the difference between lipid based synthesis in animals vs plants
animals - highly saturdated
plants - highly unsaturated
32
where are the different type of lipids found
1. tryglycerides = cereal grains, oilseeds and animal fats
2. glycolipids = forages (4-6%) of DM is lipid
3. phospholipids = high in ruminal bacteria
33
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
34
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
35
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
36
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
37
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
38
how does putting lipids in teh diet help to alleviate heat stress
- it creates a low heat increment = increasing the feed intake
-
39
how does adding lipids reduce dust
- increases palatability
- improve air quality
40
what is the usual lipid concentration in diets? what % is supplimented
- 2-4%
- adding 3-5% brings it up to 6-7%
41
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
42
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
43
what are the phases of lipid digestion
- emulsification (large fat globules into tiny droplets )
- hydrolysis
- micelle formation
- absorbtion
44
what is the role of bile salts
- created in the liver, stored in the gallbladder
- facilitates emulsification
- reabsorbed through the ileum
45
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
46
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
47
chylomicron structure
- transports dietary lipids
90% tryglycerides
4% phospholipid
5% cholesterole
1% protien
- released into lymphatic circulation cia exocytosis
- used to transfer dietary lipids
48
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
49
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
50
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
51
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
52
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
53
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
54
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
55
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
56
what are health benefits of CLA
- reduce blood pressure
- reduce cancer
- gut health
- reduce plack build up
- reduce cholesterole
57
how much additional lipids can ruminants be fed
- 6-7% maximum of the total diet
58
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
59
what arethe two mechanisms involved in reduced fibre digestion
1. form layer around feed particles (microbes are unable to digest)
2. reduce protozoa populations in rumen ( unsaturdated fats are toxic to protozoa)
60
