3. Lipids Flashcards
(88 cards)
1
Q
What are lipids?
A
Fat-like molecules that do not have the ability to dissolve in water
2
Q
Type and amount of lipids in a slice of bread
A
LOOKUP
3
Q
Type and amount of lipids in a glass of whole milk
A
LOOKUP
4
Q
Type and amount of lipids in a potato
A
LOOKUP
5
Q
Type and amount of lipids in an egg
A
LOOKUP
6
Q
Type and amount of lipids in pasta
A
LOOKUP
7
Q
Type and amount of lipids in a carrot
A
LOOKUP
8
Q
Type and amount of lipids in a steak
A
LOOKUP
9
Q
Type and amount of lipids in coffee
A
LOOKUP
10
Q
Type and amount of lipids in soda
A
LOOKUP
11
Q
Type and amount of lipids in an apple
A
LOOKUP
12
Q
What are the functions of lipids?
A
- Supply energy (9 cal/gram)
- Precursors to steroid hormones
- Provide cell structure, lipid bilayers
- Cushion organs and joints from shock and damage
- Temp regulation and insulation
- Assist w/ nutrient absorption
13
Q
What lipid is a precursor to steroid hormones?
A
Cholesterol
14
Q
List the steroid hormones.
A
- Testosterone
- Estrogen
15
Q
List the types of simple lipids.
A
- Fatty acids
- Acylglycerols
- Waxes
16
Q
What is an acylglycerol? Through what rxn is it formed?
A
A fatty acid bound to a glycerol via a condensation rxn formoing ester bonds
17
Q
List the types of waxes.
A
- Sterol esters
- Nonsterol esters
18
Q
List the types of compound lipids.
A
- Phospholipids
- Glycolipids
- Lipoproteins
19
Q
List the types of phospholipids.
A
- Phosphatidic acids
- Plasmalogens
- Sphingomyelins
20
Q
What is the most simple form of a lipid?
A
Fatty acids
21
Q
What is a triacylglycerol? Function?
A
- aka triglyceride
- 3 fatty acids bound to glycerol
- How fat is stored in our cells
22
Q
What type of structure do sterols and steroids have?
A
Ring structure
23
Q
What are phospholipids composed of?
A
- Contain a diglyceride, phosphate group, and a simple organic molecule
- Have a hydrophilic head and hydrophobic tails
24
Q
How many carbons can fatty acids have?
A
4-26 carbons
25
Describe the structure of fatty acids.
Hydrocarbon chain terminating with a carboxylic acid group
26
What categories are fatty acids classified into?
* Saturated
* Unsaturated
27
Describe the structure of a saturated fatty acid.
Chain of carbons that are fully saturated w/ H atoms
28
Describe the structure of unsaturated fatty acids.
* Chain of carbon atoms that are not all fully saturated w/ H atoms
* Form on or more C=C double bonds
29
What categories can unsaturated fatty acids be classified into?
* Monosaturated: only have 1 C=C double bond
* Polyunsaturated: have more than 1 C=C double bond
30
What are the most common dietary sources of saturated fatty acids? How many carbons does each have?
* Palmitic acid (16C)
* Stearic acid (18C)
31
What are the most prevalent unsaturated fatty acids in the American diet?
* Linoleic acid
* Oleic acid
32
What are trans fats? Health risks?
Unsaturated fats that can occur naturally, but are usually created artificially in foods
* Can raise cholesterol levels
* Negatively affect CV disease
33
What types of foods have oleic acid in high amounts?
* Olive oil
* Avocados
* Breast milk
34
Cis vs. Trans form in fatty acids
* Trans fatty acids have a linear structure similary to saturated fatty acids
* H's on either side of C=C bond are on opposite sides
* Cis fatty acids have a kink in their carbon chain
* H's on either side of the C=C bond are on the same side
35
Describe the delta system for fatty acid nomenclature.
* Includes C length, # of double bonds, and positions of all double bonds counted from delta side (carboxylic acid end)
* "(# carbons in chain) : (# double bonds) delta (# carbon where double bond occurs)"
36
Describe the omega system for fatty acid nomenclature.
* Includes C length, # of double bonds, and position of 1st double bond counted from omega (methyl) end
* "(# carbons) : (# double bonds) omega (# carbon where 1st double bond occurs)"
37
Name this fatty acid using both the delta system and omega system.
* Delta: "18:3 delta 9, 12, 15"
* Omega: "18:3 omega 3"
38
How many carbons does myristic acid have? How many double bonds?
* 14 carbonds
* 0 double bonds b/c saturated
39
What are the main essential fatty acids? What makes them essential?
Must be consumed in the diet b/c the body can't make fatty acids w/ C=C bonds at carbon 3 or 6
* Linoleic acid
* Alpha linolenic acid
40
How many carbons and double bonds does linoleic acid have?
* 18 carbonds
* 2 double bonds
41
How many carbons and double bonds does alpha linolenic acid have?
* 18 carbons
* 3 double bonds
42
What are the benefits of Omega-3 fatty acids?
* Help w/ CVD
* Brain health
* Prevents inflammation and arthritis
43
What percent of the brain is fat?
60%
44
What is a monoglyceride? Diglyceride? Triglyceride?
* Monoglyceride: 1 fatty acid bound to glycerol
* Diglyceride: 2 fatty acids bound to glycerol
* Triglyceride: 3 fatty acids bound to glycerol
45
What occurs during a dehydration rxn?
A hydrogen from the hydroxyl group of the glycerol molecule and a hydroxyl group fron the carboxyl side of the fatty acid join to form an ester bond and H2O is released
46
In what forms do triglycerides exist? What does the form depend on?
Fats or oils depending on nature of fatty acid components
47
Melting point, form at room temp: saturated vs. unsaturated fats
* Saturated fats: higher mp; more likely to be solid at room temp
* Unsaturated fats: lower mp, more likely to be liquid at room temp
48
What is cholesterol? Source? Function?
* An animal sterol obtained from animal sources
* Component of cell membranes
* Precursor for steroids
49
What are phytosterols? How many are there in nature?
* Plant sterols
* Over 200 in nature
50
Do plants contain any cholesterol?
No
51
What is the function of phospholipids?
Major component of cell membranes b/c they form lipid bilayers
52
What is a phosphatidylcholine?
A phospholipid w/ a cholin attached
53
What is a phosphatidylserine?
A phospholipid w/ a serine attached
54
How does cholesterol benefit phospholipid bilayers?
* Helps strengthen bilayer
* Decreases permeability
* Regulates activity of certain membrane proteins
55
What does lingual lipase do? Where is it located?
* In the mouth
* Hydrolyzes the short-chain saturated fatty acids on triglycerides such as those in palm oil, coconut and mother's milk
56
What does gastric lipase do? Where is it located?
* In the stomach
* Hydrolyzes the medium and long-chain triglycerides
57
List the acidic lipases. Characteristics?
* Lingual and gastric lipases
* Don't need bile or colipase to function
* Need a certain low pH to work
* Can only cleave 1 FFA from a triglyceride
58
What is a pancreatic lipase? Function?
* Alkaline lipase that needs bile and colipase to function properly
* Works at higher pH levels
* Can hydrolyze ester bonds in triglycerides to monoglycerides + 2 FFA
59
What % of triglyceride digestion do lingual and gastric lipases account for? Pancreatic lipase?
* Lingual and gastric lipases = 30%
* Pancreatic lipase = 70%
60
What are bile salts? Function?
* Act as emulsifier of lipids (makes fat droplets smaller and more water soluble)
* Ampiphatic (have both hydrophobic and hydrophilic groups)
61
What are micelles?
Smaller fat droplets that have been coated in phospholipids and bile salts
62
What do micelles contain to increase its surface area? Significance?
* Contain the products of partial lipid digestion (monoglycerides, fatty acids, cholesterol) combined w/ bile salts
* Aids digestion b/c pancreatic lipase (fat-digesting enzyme) can only act on the surface of the fat droplet
63
What is pancreatic lipase? Function?
Fat-digesting enzyme that will cleave fatty acids off of triglycerides --\> results in FFA and monoglycerides
64
What is cholesterol esterase? Function?
An enzyme that will de-esterify (remove the fatty acid from) cholesterol esters
65
What does phospholipase A2 do?
Digests phospholipids
66
What are the digestive products of lipids?
FFAs and monoglycerides
67
What is lipoprotein lipase? Function?
Enzyme released from enterocytes that can break down micelles and cause them to release their lipid contents
68
What is the endoplasmic reticulum? Function?
A system inside the cell whose functions include synthesis and transport of lipids
69
What makes fat absorption different than protein and carb absorption?
* Fats are reformed into triglycerides in the ER
* Fats enter lymphatic system
70
What is a chylomicron? Where are they made? Function?
* A type of lipoprotein that has a phospholipid **_mono_**layer
* Made in the enterocytes of the small intestine
* Transports exogenous (outside the body; from food) dietary lipids (triglycerides) from small intestine to the liver and other tissues
71
What is the main apoprotein on a nascent chylomicron?
ApoB48
72
What are the functions of apoproteins?
* Bind and stabilize lipid molecules into a lipoprotein particles
* Transport lipids through the lymphatic and circulatory systems
* Associated w/ and modulate activity of enymes that process lipids
* Serve a ligands for specific receptors that mediate lipoprotein clearance by endocytosis
73
What is ApoB48? Where is it produced? Function?
Produced in the intestine, where it is necessary for the formation of chylomicrons
74
What does VLDL stand for? Function of both?
* VLDL: very low density lipoprotein
* Transport endogenous lipids (triglycerides) from liver to body cells
75
What is the largest and least dense of all the lipoproteins? Why?
Chylomicrons b/c they are the most full of triglycerides (less dense than proteins)
76
What does LDL stand for? Function?
* Low density lipoprotein
* Transports cholesterol from liver to body cells
77
What does HDL stand for? Function?
* High density lipoprotein
* Transports cholesterol from body cells to liver
78
What makes lipoprotein more dense?
Contains more protein that triglycerides
79
Describe the pathway of chylomicrons throughout the body.
1. Nascent cholymicrons bypass liver circulation and are drained via the thoracic duct into the bloodstream
2. In blood stream, nascent chylomicrons pick up apoproteins from HDL --\> now considered "mature" chylomicrons
3. Chylomicrons drop off their triglycerides in tissues and return to the liver as chylomicron "remnants" --\> repackaged as VLDLs and returns to circulation
* Arterial epithelial cells secretes lipoprotein lipase that can breakdown the phospholipid shell of VLDLs to release their lipid contents into the blood
4. Repackaged as IDL --\> goes back to liver
* can be recycled or stay in circulation to release cholesterol into extrahepatic cells
5. Repackaged in liver as HDL --\> take cholesterol back to liver
80
How can LDLs enter arterial cells? Significance?
* If LDL particles are small enough or if artery wall is damaged
* Can form plaque and clog arteries
81
What is reverse cholesterol transport? Significance?
HDL takes cholesterol that has been deposited in the arterial wall back into circulation --\> slows down plaque formation
82
What is the role of the liver in lipid metabolism?
* Synthesizes bile salts
* Synthesizes lipoproteins
* Synthesizes new lipids from non-lipid precursors (lipogenesis)
83
What is the role of adipose tissue in lipid metabolism?
* Absorbs triglycerides and cholesterol from chylomicrons through lipoprotein lipase
* Stores triglycerides
84
What is the role of insulin in lipid metabolism?
* Helps get circulating FFAs into cells by activating lipoprotein lipase
* Turns on enzymes in adipocytes to increase triglyceride synthesis and storage
* Turns off enzymes that are involved in triglyceride breakdown
* Accelerates the influx of glucose into adipocytes, which can then be converted to fatty acids and stored as triglycerides
85
What hormones are released during a fasted state?
* Glucagon
* Catabolic hormones (epinephrine, thyroid hormones, growth hormone, glucocorticoids)
86
Describe lipid metabolism in a fasted state.
* Decreased insulin activates hormone sensitive lipase
* Increases rate of lypolysis
* Releases fatty acids into circulation
* Fatty acids are taken up by the liver and muscles and oxidized for energy
87
What does the liver do during a fasted state?
Makes ketone bodies from acetyl-CoA to use for brain and muscle fuel during starvation states
88
