Lipids (midterm) Flashcards
What is the monomer of lipids?
TGs
FAs are rarely free in nature, they are usually linked to other molecules by their….
hydrophilic carboxylic acid group
FAs primarily exist as….
unbranched hydrocarbon chains
How are FAs classified?
1) number of carbons
2) number of double bonds
3) position of the last double bond in the chain
What are SCFAs found in?
-breast milk
-coconut oil
-dietary soluble fiber
SCFAs have how many carbons?
less than 6 carbons
ex:
-acetate has 2 C
-propionate has 3C
-butyate has 4 C
MCFAs have how many carbons?
6-12 carbons
ex: lauric acid has 12 C
T/F: MCFAs need bile for absorption
false
MCFAs is found in what oil?
coconut (also has SCFAs in there)
What are the 2 health benefits of MCFAs?
-facilitates weight loss
-can treat neurodegenerative diseases
Most FAs in nature are- SCFAs, MCFAs, or LCFAs?
LCFAs
How many carbons are there in LCFAs?
12+ carbons
ex: palmitate has 16 carbons
What are the 2 subclasses for LCFAs?
MUFAs (omega 9) and PUFAs (omega 3 and 6)
What are the 3 health benefits of SCFAs?
-good for baby
-keeps colon cells healthy
-keeps gut flora healthy
What does a saturated FA structure look like?
no double bonds
Are saturated FAs usually short or long?
long
Are saturated FAs usually solid or liquid at room temp?
SOLID (some are liquid like palm oil and coconut oil, but butter, lard, and animal fat are solid)
Which FAs have a higher melting and smoke point?
saturated FAs
What food has saturated FAs?
-butter, lard, animal fat
-palm oil
-coconut oil
Saturated fats in general are associated with increased serum _____________ levels and higher _______
cholesterol, LDLs
What does an unsaturated FA structure look like?
with double bond (if carbons are on same side = cis double bond, if opposite sides then its a trans double bond)
Are MUFAs liquid or solid at room temp?
test q
liquid
Are MUFAs liquid or solid in the refrigerator?
test q
solid
oleate has what omega classification?
omega 9
Oleate is extracted from which oil?
olive oil
Which FA has lower smoke points and is not good for high heat cooking methods such as frying?
MUFAs
What are some examples of MUFA food sources?
test q
-olive oil
-canola oil
-safflower oil
-peanut oil
-most nuts in general
-avocado
If you burn oil and it smokes then it will make carcinogens and release it into your food. How do you prevent this?
add oil and food at the same time so that the food will absorb the oil rather than heating the oil first and getting overheated
Which FA is liquid at room temp and refrigerator?
PUFA
Which omega classifications are PUFAs?
omega 3 and 6 FAs
What are the 2 important PUFAs that are essential?
1) linoleic acid (18:2, omega 6)
2) alpha linolenic acid (18:3, omega 3)
How many carbons and double bonds are there in linoleic acid?
18:2
What is the omega classification for linoleic acid?
omega 6
How many carbons and double bonds are there for alpha linolenic acid?
18:3
What is the omega classification for linolenic acid?
omega 3
Which omega class should we try to eat the most?
omega 3
What foods have omega 3 FAs?
-salmon
-tuna
-herring
-mackerel
-cod liver oil
-flaxseeds
-walnuts
-wheat germ oil
Eicosapentanoic acid (EPA) 20:5 and docosahexaenoic acid (DHA) 22:6 are related. Both of these are metabolized to form….
omega 3 eicosanoids
What is the recommended intake of fish per week?
2x a week
Human brains and CNS cell membranes require ___________ for optimal function
EPA/DHA
Increased omega 3 FA in the diet is associated with:
-decreased incidence of cardiovascular disease
-decreased plasma TG levels
-decreased inflammatory disorders
-decreased symptoms of RA
-decreased severity of asthma in children
-improved lung function in people with cystic fibrosis
-decreased severity of symptoms in psychiatric disorders like schizophrenia and depression
-decreased incidence of colon, breast, prostate, and lung cancers
-decreases symptoms of ADHD in children
Omega 6 FA is found in what foods?
veggie oil
How much veggie oil (omega 6 FA) should you consume a day?
1 tablespoon
Arachidonic acid 20:4 can be made from omega 6 linoleic acid. Arachidonic acid is considered conditionally essential. It is metabolized to form….
omega 6 eicosanoids like prostaglandins, thromboxanes, and leukotrienes
Eicosanoids are made when released by what enzyme?
phospholipase A2
Eicosanoids mediate what?
-pain sensation
-immune function
-vasodilation/constriction
-inflammation
-blood clotting
-muscle contraction
-short term memory
-intestinal motility
Aspirin is an irreversible inhibitor of?
cyclooxygenase (COX 1 and 2, aka prostaglandin and thromboxane)
What is the function of omega 6 eicosanoids like arachidonic acid?
-increase blood clotting
-increase inflammatory responses
What is the function of omega 3 eicosanoids like DHA and EPA?
-decrease blood clotting
-reduce risk of heart attack
T/F: almost all cells in the body are capable of producing eicosanoids
true
T/F: all eicosanoids have the same effect on different tissues
false
What percentage of Americans are deficient in essential FAs?
60%
What are the signs and symptoms of essential FA deficiency?
-flakey, itchy, dry skin
-dry hair
-infections
-impaired vision
-reduced learning
-hyperactivity in kids
-memory problems
-allergies
-inflammatory diseases
-depression
-violence
-heart disease
-arthritis
-soft nails
-polydipsia (excessive thirst)
Which oil is the highest in saturated fat?
test q
coconut oil
Which oil is the highest in MUFAs (omega 9 oleic acid)?
test q
safflower oil and olive oil
Which oil is the highest in alpha linolenic acid (omega 3, PUFA)?
flaxseed oil
Which oil is the highest in linoleic acid (omega 6, PUFA)?
sunflower oil
What is hydrogenation of FAs?
-process is used to solidify an oil to increase the melting temp
-addition of H to carbon double bonds
-formation of trans FA, which increases shelf life
What foods are high in trans FAs?
-hydrogenated fats
-deep fried food
-high fat baked goods
-non-diary creamers
-salty snacks
-commercial cakes, cookies, and other baked goods
Excessive trans fat intake raises _______ and lower _______
LDL, HDL
Excessive trans fat intake increases risk for what disease?
heart disease
How much cholesterol should we consume a day?
200-300 mg
Low fat diet is not recommended for who?
children under 2 y/o
Which FAs emulsify food during digestion?
MG and DGs
What is the most efficient energy storage?
TGs
Hydrolysis of 2 monoglyceride results in:
1 glycerol + 1 FA
What are the simple lipids?
-MG, DG, TGs
-waxes (esters of FAs w/ high molecular weight alcohols)
What are the compound lipids?
-phospholipids
-sphingolipids
-lipoproteins
What makes up a phospholipid?
-glycerol backbone
-phosphoric acid
-2 FAs
What is the key source of intracellular signaling agents (eicosanoids, inositol, and choline)?
test q
phospholipids
What makes up a sphingolipid?
-sphingosine backbone
-1 FA
-polar head group
ex of sphingolipids:
-ceramide
-sphingomyelins
-gangliosides
-cerebrosides
Sterols and steroids come from where?
-cholesterol (animal products)
-plant sterols (5% of dietary lipids, can block bile and cholesterol absorption)
What are the functions of sterols and steroids?
-membrane and lipoprotein component (cholesterol)
-hormones (precursors for vit D, estrogen, and progesterone)
-bile salts (solubilize lipids during digestion)
Which 2 molecules are completely hydrophobic?
TGs and cholesterol ester
How do we degrade hydrophobic molecules in a hydrophilic environment?
emulsify lipids with bile salts
Are there any lipid digestion enzymes in the mouth? If so, what are they?
-lingual lipase aka gastric lipase
-important largely for infants
-acts on breast milk fats (short-medium chain length FAs)
Are there any lipid digestion enzymes in the stomach? If so, what are they?
none
What slows the release of food from the stomach?
fat
Which part of the body performs 90% of all lipid digestion?
SI
When lipid rich chyme enters the duodenum, the gallbladder is stimulated by CCK to release bile acids. The SI mixes bile salts to convert lipid emulsion into __________. The SI primarily performs __________ and _________________
micelles, hydrolysis, de-esterification
Enzymes for lipid digestion are secreted from the ____________ and are stimulated by ________
pancreas, CCK
Which digestive enzymes help break down lipids and are secreted from the pancreas?
-pancreatic lipase + colipase
-phospholipase A2
-cholesterol esterase
Pancreatic lipase and colipase act on the 1st and 3rd position of _______
TGs
Phospholipase A2 acts on the ______ position of phospholipid
2nd
Once phospholipids are cleaved at C2, what enzyme comes in next to break it down more?
lecithinase
What is the function of cholesterol esterase in low pH environment (usually in lumen)?
will remove FA from cholesterol ester to make cholesterol + FA
What is the function of cholesterol esterase in high pH environment (usually the mucosa)?
will add FA to cholesterol to make cholesterol ester
Dietary lipids must be de-esterified into free FA and MG and cholesterol to get into the mucosal cell (TGs and cholesterol esters are too large for movement across cell membranes). The lipids are packaged as _________________ in the mucosal cells and enter into circulation via the lymphatics and _______________
test q
chylomicrons, L subclavian v.
What does “apo” mean?
protein part of apolipoprotein
Chylomicron and chylomicron remnants are made in the _______ with dietary lipids 1-2 hours after eating a high fat diet. Blood will look milky from the high fat
SI
What are the bad (non-HDL) lipoproteins?
test q
1) chylomicron and chylomicron remnant
2) VLDL (very low density lipoprotein)
3) IDL (intermediate density lipoprotein)
4) LDL (low density lipoprotein)
What is the good lipoprotein?
test q
HDL (high density lipoprotein)
What are apolipoproteins?
-the protein component of lipoproteins
-stabilize lipoproteins as they circulate thru the vasculature
-confer specificity allow for recognition by other lipoproteins and cell receptors
-designated by series of letters A-E
What is the largest and least dense of lipoproteins?
chylomicrons
chylomicrons transport….
test q
dietary lipids (primarily TGs and cholesterol ester from the SI to the rest of the body via lymphatics)
Chylomicrons obtain apolipoprotein _______ within the enterocytes, unique to the chylomicrons
test q
B48
note: this is a marker that can be seen in blood work
Chylomicrons obtain apo ______ and _______ from HDLs once they reach the blood
test q
C2, E
Is apo B48 an integral or peripheral protein?
integral
Are apo C2 and E integral or peripheral proteins?
peripheral proteins
Chylomicrons decrease in size as they deliver dietary TGs to peripheral tissues. At this point, _________ is returned to HDL
apo C2
Chylomicron remnants are recognized by receptors on membranes of the liver via ____________ and removed, disassembled and repackaged into ______
apo B48 and E, VLDL
Apo C2 is found where?
peripherally on chylomicrons, VLDL, and HDL
Which apolipoprotein is the activator of lipoprotein lipase (breaks down TGs in chylomicrons) found on endothelial vessel walls lining tissues such as adipose and muscle?
apo C2
(this releases the FAs from TGs in chylomicrons/VLDL for cellular uptake and usage as either energy (muscle) of storage (adipocytes)
T/F: dietary fat is directly dumped into adipocytes if the body is getting enough energy from protein intake
true
Chylomicrons will shrink after products are released. What apoproteins are still there?
B48 and E
Chylomicron remnant enters liver cells via what transport process?
receptor mediated endocytosis (and then it will be broken down by lysosome)
Very low density lipoproteins are generated where?
from liver
The liver takes the remaining lipid from the chylomicron remnants by receptor mediated endocytosis, along with other lipids generated from the liver and repackages them into _________
VLDLs
VLDLs obtain apo _____ in the liver
test q
B100
VLDLs obtain apo ________ from HDLs in the blood
C2 and E
As VLDLs travel thru the body, cells remove TG causing the VLDL to shrink. This alters the proportion of lipids, and the lipoprotein becomes denser. The remaining VLDL mutates into an _______, then ________, and then returns apo C2 and E back to the HDLs
IDL, LDL
What apolipoproteins does IDL have? What is the difference between VLDLs?
-same apo as VLDLs, so apo B100, C2, and E
-difference is the size, IDL is smaller and cholesterol stays
What apolipoproteins does LDL have? How is this different from IDL?
-IDL has the same apo as VLDLs but LDL has shrunk even more so it only has B100
-cholesterol is still here just like with IDL and VLDLs, but the cholesterol conc. increases here bc the lipoprotein has gotten much smaller and denser
Macrophages can breakdown proteins and phospholipids but NOT ______________
cholesterol
LDLs have a high conc. of _________ and low conc. of _____
chol, TGs
What is the function of LDLs?
they circulate and make chol available to cells of all tissues
-all tissues need chol for vitamin D, hormones, etc
-“kiss and touch” can just give chol to whoever needs it
-if no tissue needs chol then it’ll just go back to liver
Is apo B100 an integral or peripheral protein?
integral protein
In the liver, special LDL receptors recognize apo B100 by removing LDLs from circulation via….
receptor-mediated endocytosis
If theres too much LDL in the body, what happens?
bad stuff- apo B100 will get damaged and cause LDL to become oxidized, but this means it cant go back to the liver, so it will precipitate in the wall of an artery, deposit there, make foam cells and increase BP
LDL receptors are negatively charged glycoproteins and are clustered on pits on cell membranes. The intracellular side of the pit is coated with the protein ____________, which stabilizes the pit
clathrin
T/F: everyone has some LDLs and oxidized LDLs
true
After gastric bypass, the body is forced to make more ______
HDL
Where is HDL made?
in the liver and intestines
What is the smallest lipoprotein?
HDL
Which lipoprotein has the highest conc. of protein?
HDL
Which apolipoprotein is unique to HDL?
test q
apo A
HDL serves as a _________ for other apolipoproteins, such as apo E and C2
reservoir
HDL picks up unesterified cholesterol from dying cells and other sources and esterifies the cholesterol by its enzyme…
phosphatidylcholine cholesterol acyltransferase (PCAT), or another name for it is lecithin cholesterol acyltransferase (LCAT)
A phospholipid with a choline attached to the phosphohead of the 3rd carbon is called:
lecithin
HDL transfers chol from other lipoproteins to the liver for…
recycling or disposal
Which lipoprotein plays a key role in cholesterol homeostasis?
HDL
Which lipoprotein can dissolve plaque in arteries?
HDL
lecithin + cholesterol with LCAT = ?
lysolecithin + cholesterol ester
What is lysolecithin?
-one of the products after LCAT or PCAT adds FA to cholesterol
-lysolecithin has only one tail and is a detergent
-lysolecitin can promote the liver to pick up HDL thru endocytosis
Which organ is the ONLY organ that can process cholesterol ester?
test q
liver
What is atherosclerosis?
-plaque build up in arteries
-plaque is mostly cholesterol but also has calcium and fibrin in it
-can start as early as childhood if they eat high chol foods frequently
-if the artery gets completely blocked with plaque then it will cause a heart attack
Where does VLDL come from?
liver
Which lipoprotein transports endogenous TGs to peripheral tissues?
VLDL
Where does LDL come from?
IDL
Which lipoprotein transports endogenous cholesterol to peripheral tissue?
LDL
Which lipoprotein converts cholesterol to cholesterol ester and transports it back to the liver?
HDL
How are FAs transported in the blood?
with albumin
How are dietary TGs and chol ester transported in the blood?
chylmicrons
How are endogenous TGs transported in the blood?
VLDL or IDL
How is endogenous chol transported in the blood?
LDL
How is endogenous chol ester transported in the blood?
HDL
High _______ are associated with a high risk of heart disease whereas high _______ have a protective effect
LDLs, HDLs
What should our HDL be ideally in males and females?
more than 40 mg/dL in males, more than 60 mg/dL in females
What is hyperlipidemia?
-decreased HDL
-increased LDL and/or increased TGs
What are the risk factors for heart disease?
-family hx
-smoking (increases inflammation, depletes HDL and increases ROS)
-elevated BP
-hyperlipidemia (HDL is less than 35 mg/ dL)
- high blood chol
-diabetes
-lack of regular exercise and obesity
-homocysteinemia
-c-reactive protein
-increased apo B particles
What is homocysteinemia?
-associated with neuro and cardio diseases
-vitamin deficiency in B6, B9 (folic acid), and B12 is the major cause
-this causes homocysteine build up in the blood
-this is an independent risk factor for cardiovascular disease
What should you do to reduce your risks of heart disease?
reduce chol levels by:
-reducing dietary saturated fat, trans fat, and chol
-reducing refined carbs
-increasing dietary fiber and folate
-increasing plant steroids and sterols
reduce oxidation and inflammation by:
-increasing plant antioxidants and phytochemicals
-moderating PUFAs and increasing MUFAs (good fats)
-increase vit B6, B9, and B12
increase HDL by:
-increasing physical activity
-adequate caloric intake to maintain a healthy weight
-moderate alcohol intake like with red wine
-nicotinic acid (vit B3)
-statins
-quit smoking
-estrogen
-weight
-exercise
-reduced high TG diet
Which of the following is the best source of MUFAs?
A) olive oil
B) coconut oil
C) fish oil
D) flaxseed oil
A) olive oil
Cholesterol is not a precursor of ____?
A) cholic acid
B) vit D
C) estrogen
D) lecithin
D) lecithin
A lack of lipoprotein lipase results in:
An elevated level of chylomicrons following a high fat diet
TGs are transported from intestinal cells to adipose tissues within:
Chylomicrons
