Chapter 5 - Lipids Flashcards
tricglyceride
- most common lipid in food & body
- major storage form of fat in the body
- composed of 3 fatty acids attached to a glycerol
What’s the difference between triglycerides & phospholipids?
triglycerides are stored fats (plant oils from seeds, fruits, fish oil, solid fats, butter, meat fats, tested for in blood
phospholipids - structural fats; plant and animal cell membranes
fat vs. fatty acid
fatty acids are a chain of carbon & hydrogen atoms w/an acid group (COOH) at one end & a methyl group (CH3) at the other.
- differ in the length of carbon chains & # & location of their double bonds
fats = triglycerides, phospholipids
chemical make up of fatty acids
same basic structure - chain of carbon & hydrogen atoms w/an acid group (COOH) at one end and a methyl group (CH3) at the other end
- can differ:
- in length of carbon chains
- # & location of double bonds
monounsaturated fatty acid
one double bond
- olive & canola oil
polyunsaturated fatty acid
- has two or more double bonds
- sunflower & soybean oils
saturated fats
- most animal fats
- no double bonds
omega number
indicates the position of the first double bond away from the methyl end
omega-3 fatty acid - double bond is 3 carbons away from end
what are the individual components of
- triglycerides
- phospholipids
- triglycerides - a lipid composed of 3 fatty acids attached to a glycerol
- phospholipids - a glycerol with 2 fatty acids & a phosphate group & a molecule of choline
saturated fatty acids
- firm at room temp
- chains of fatty acids are straight so lay flat & stays firm
- animal fats, some oils
unsaturated fatty acids
- tend to be liquid at room temp
- fatty acids are bent due to the double carbon bonds
- most abundant in seeds, nuts, some fruits (olive, avocado), marine animals
What’s difference between saturated & unsaturated fatty acids?
saturated - no double bonds, so straight
- none are essential (our bodies can make them)
- solid at room temp
unsaturated - double bonds make them curve
- some are essential (need from food)
- liquid at room temp
How can unsaturated fatty acids aid organisms to adapt to cold weather?
B/c unsaturated fatty acids are bent, they tend to keep things more fluid and store more of them in their tissues to keep them from freezing/becoming solid.
Explain: omega-3 fatty acid
- means the first carbon double bond is 3 carbons from the methyl bond/end
- is found in flax seed, walnuts, soybean, hemp seed, fish oil, green plants (ultimately all omega-3 is from green plants)
Explain: omega-6 fatty acid
- first carbon double bond is 6 carbons from the methyl group
- linoleum acid
- found in most seeds, germ of grains, walnuts, soybeans
Explain: monounsaturated fatty acid
- one of two types of unsaturated fatty acids
- omega-9
- oleic acid - found in olive oil, avocado, cashew, almond, hazelnut, pistachios, macadamia, peanuts
Name the two types of unsaturated fatty acids
- monounsaturated - one double bond
- omega-9
- polyunsaturated - many double bonds
- some are essential
- omega-3
- omega-6
What are trans fatty acids?
- result from the conversion of omega-6 fatty acids to saturated fatty acids.
- are rich in highly processed foods
point of unsaturation
the double bond of a fatty acid; where hydrogen atoms can easily be added
hydrogenation
- some or all of the points of unsaturation (no H) are saturated by adding H molecules
- protects against oxidation (rancidity)
- process produces trans-fatty acids
- total hydrogenation rarely takes place - usually a fat is partially hydrogenated
cis-fatty acid
trans-fatty acid
cis = H on the same side, causing a bend
trans = H on opposite sides causing fatty acid to straighten
How are trans-fatty acids generated?
Oil is heated in the presence of hydrogen gas & a catalyst like nickel
Why are trans-fatty acids used in food processing?
the hydrogenation process:
- extends shelf life of items
- makes oils more firm; affects texture of foods
Why to trans-fatty acids place your health at risk?
In the body, they act more like saturated fats:
- increase blood cholesterol
- increase risk of heart disease
phospholipids
- have a hydrophilic (water loving) head - the glycerol & phosphate group & choline end
- have a hydrophobic (water fearing) region - the fatty acid part
roles of phospholipids
- B/c are both water & fat soluble, they help fat soluble vitamins & hormones pass easily in & out of cells.
- used as emulsifiers - help keep fats suspended in the blood & bodily fluids
lecithin
best-known phospholipid
sterols
a form of lipid
- includes: bile acids, sex hormones, adrenal hormones, Vit D & cholesterol
cholesterol
endogenous - that is made in the body
- body makes 800-1500 mg/day
exogenous - from outside the body
harmful effects occur when it accumulates in the artery walls – contributes to plaque
cholecystokinin (CCK)
- release is triggered by fat entering the small intestine
- triggers gall bladder to release bile
lipoprotein
- a spherical particle in the blood that consists of phospholipids, protein, triglycerides, & cholesterol
- transport fats through blood
LDL
- low density lipoprotein (bad cholesterol)
- derived from VLDL as triglycerides are broken down & removed
- composed primarily of cholesterol
- LDL receptors in liver responsible for removal of LDL from circulation
chylomicrons
- largest and least dense of lipoproteins
- transport diet-derived lipids (mostly triglycerides from small intestine (via lymph system) to the rest of the body
- as pass thru the body, triglycerides are removed by cells
- once depleted, liver removes the remnants from blood
VLDL
very low density lipoproteins
- made by liver cells to transport lipids to various tissues in body
- composed primarily of triglycerides
- as triglycerides are removed, mostly cholesterol is left
HDL
high density lipoproteins
- transports cholesterol back to the liver from the cells
- composed primarily of protein
- has a protective effect
What are some important functions of cholesterol?
- builds and repairs cell membranes
- precursor to:
- vitamin D
- bile formation
- steroid hormones (cortisol, aldosterone, estrogen, progesterone, testosterone (sex hormones)
essential fatty acids
- the fatty acids the body cannot make & must get from food
- Omega-6 (linoleic acid) and -3 (linolenic)
- obtained from vegetable oils, seeds, nuts, fish & seafood
What’s the difference between “good” and “bad” cholesterol?
- HDL (good) carries cholesterol from the tissues back to the liver for excretion (protective)
- HDL is comprised of 1/2 protein
- LDL (bad) is comprised of 1/2 cholesterol
- LDL carries triglycerides, cholesterol, & phospholipids to cells for energy
What foods are rich in cholesterol?
eggs
milk & milk products
meat, poultry & shellfish
DRI & dietary guidelines for fat
20-35% of energy intake
