Lipids - Chapter 6 Flashcards
Lipids
Substances soluble in organic solvents
Hydrophobic
“Water-hating” “water-fearing”
Repelled by water
Lipophillic
Lipids are lipophillic
“fat loving”
attracted by lipid
Where is most of the lipid stored?
In the bodies of animals
Organic
- A complex chemical containing carbon in its structure.
- Often formed in a bioogical process
What form is most inorganic carbon in?
Carbon dioxide in the atmosphere
Three kinds of lipids
- Triglycerides
- Phospholipids
- Sterols
Triglyceride
- A type of lipid formed by three fatty acids arrayed on a glycerol backbone
- Most fats occur in the triglyceride form
Phospholipid
- A type of lipid similar to a triglyceride in which one of the fatty acids is replaced by a phosphorous-containing compound
Sterol
- A type of lipid with a multiple ring structure, such as cholesterol
Fatty acid
- A lipid formed of a chain of carbon atoms, saturated by hydrogen atoms to varying degrees, with a methyl group on one end and a carboxyl group on the other
Methyl
- the omega end
- the chemical group -CH3
Carboxyl
- alpha end
- the chemical group -COOH
Valence
The characteristic number of chemical bonds formed by a particular chemical element
Valence of hydrogen
1
Valence of oxygen
2
Valence of carbon
4
Saturated fatty acid (SFA)
A fatty acid in which all of the carbon-carbon bonds are single bonds. It is saturated with hydrogen atoms, that is, it contains all the hydrogen it can in its structure
Found in animal products
Butryic (4C) Caprylic (8C) and stearic (18C)
Acids that are typical of saturated fatty acids
Saturated fats worst
Worst dietary contributor to the development of heart disease
point of unsaturation
A double bond in a fatty acid.
Not saturated by hydrogen atoms; more hydrogen could be added where the double bond is to be split
Monounsaturated Fatty Acid (MUFA)
A fatty acid containing a single point of unsaturation, that is, a single double bond, in its structure
Found in vegetable fats including Olive oil
Lower freezing point
liquid at room temperature - cloud or get stiff if in refrigerator
Oleic acid (18C)
Makes up most of olive oil (a MUFA)
Saturated fats raise what?
Blood cholesterol
Other examples of monounsaturated fats
Canola oil, sesame oil, walnut oil, and avocado oil
lowers blood levels of cholesterol and are not associated with an increased risk of disease
polyunsaturated fatty acid (PUFA)
A fatty acid containing more than one point of unsaturation, that is, more than one doulbe bond
Found in vegetable fats
2-6 double bonds
stay liquid in freezer
18:3 fatty acid
18 carbons with 3 double bonds
Examples of saturated fatty acids
Coconut oil
Butter
Palm oil
Lard or beef fat
Examples of monounsaturated fatty acids
Olive oil
Canola oil - also rich in omega-3
Peanut oil
Soybean oil - also rich in omega-3
Linoleic acid
An 18:2 omega-6 polyunsaturated fatty acid
An essential fatty acid
Omega-6 Polyunsaturates
Most common vegetable oils
Corn, safflower, soybean, cottonseed, and sunflower
Lower both the desirable and undesirable types of cholesterol so = mixed blessing in heart disease prevention
Eicosapentanoic acid
A 20:5 omega-3 polyunsaturated fatty acid.
Found in fish
Docosahexanoic acid
A 22:6 omega-3 polyunsaturated fatty acid
Found in fish
Omega-3’s are mainly:
Fish oils
Omega-3 can also occur in what:
Plants as alpha-linolenic acid (18:3)
found in flax, canola, soy, and other oils
fat is converted to EPA in body
Lower risk of heart attack
Alpha-linolenic acid
An 18:3 omega-3 fatty acid.
Essential fatty acid
Found in flax, canola, and soy oils
Fats consist of a mixture of fatty acids but one particular fatty acid usually dominates
Increasing saturation
raises the melting point of a fat
Saturated fats get
stiff at low temperatures
Cold climate plants
Are highly polyunsaturated
Corn, soybeans, and sunflowers
Warmer climate plants
Maintain fluidity using monounsaturated fats
olives
Really warm climate plants
Use saturated fats
tropical oils, palm, palm kernel, and coconut
Percent of triglycerides
98 percent of the time, fatty acids are assembled into triglycerides
What are triglycerides made from?
Three fatty acids arranged on a glycerol backbone
Hydrogenation
A process by which unsaturated fats become saturated. Hot hydrogen gas is bubbled through the fat. Some of the double bonds break, to be replaced by extra hydrogen atoms. Can be carried through to any degree of saturation
cis-bond
same
trans bond
across
Trans-fatty acid
Unsaturated fat in which one of the double bonds is in the trans-form.
Formed in partially hydrogenated fats when double bonds break and reform
Not found in nature, but only in our food supply.
Rancidity
The off-flavor caused by oxidation of lipids
Peroxidation
The process by which free radical oxygen attacks a double bond in a fat
Causes rancidity
Free radical
A very reactive species of oxygen, in which one of the electrons has been lost, creating an unstable electron shell
Attack lipids and other cellular substances
Antioxidant
Substance which protects cellular components against oxidation by reacting with free radical oxygen itself
Examples of antioxidants
Vitamin A
Vitamin C
Vitamin E
Sources of phospholipids
Soybeans and egg yolks
our body synthesizes all we need
replace one of the fatty acids in a triglyceride with a phosphorous-containing compound
Cholesterol
Sterol with multiple ring structure, synthesized by the body and used to manufacture steroid hormones and other substances
Found only in animal foods
Phospholipids are important
in cell membrane structure, and are used in food processing as emulsifiers
example: Licithin
Examples of sterols
Many hormones - estrogen and testosterone = steroids
Vitamin D
cholesterol
Olestra (Olean)
A non-absorbable fat substitute made by attaching fatty acids to a sucrose backbone
primary fat substitute on the market
yields no calories
sucrose polyester = consists of seven to nine fatty acids on a sucrose backbone
cant be digested
Mouthfeel
Forming the texture and the feel of the food when we eat it
Fat contributes to this
Lipids are not
water soluble
Monoglyceride
A single fatty acid attached to glycerol
Formed by digestion of triglyceride
Chylomicron
Large lipoprotein that transports lipid from the gut, delivering dietary triglyceride to body cells and cholesterol to the liver
Lipoprotein Lipase
Enzyme attached to artery wall that breaks down triglyceride from lipoprotein into free fatty acids and glycerol
endogenous
made within the body
Very low density lipoprotein (VLDL)
Lipoprotein formed in the liver which transports endogenous triclygeride to body cells. It also receives cholesterol from HDL for return to the liver
High density lipoprotein (HDL)
Lipoprotein which scavenges cholesterol from body cells and arterial plaque and transfers it to VLDL remnants for return to the liver and excretion
Associated with a lower risk of heart disease
Primary site for digestion and absorption of lipids
Small intestine
How much of ingested fat is excreted in feces?
5%
Low Density Lipoprotein (LDL)
Lipoprotein formed in the liver which transports cholesterol to body cells and arterial plaques
Associated witha higher risk of heart disease
Receptor
Protein on a cell membrane which recognizes and binds a specific substance in the blood, such as LDL or estrogen
plaque
Arterial lesion formed by deposit of cholesterol
the good cholesterol
HDL
Protective against heart disease
pulls cholesterol out of the arterial plaques
Short and simple: chylomicrons
Bring dietary lipids from the gut and deliver triglyceride throughout the body
Short and simple: VLDL
formed in the liver
delivers triglyceride synthesized in the liver
Short and simple: LDL
Delivers cholesterol throughout the body for vital uses and to clog your arteries
Short and simple: HDL
svavenges cholesterol from cells and from your arteries, and carries it to VLDL remnants for transport back to the liver and excretion
LDL is cholesterol on the way into the body, while HDL
HDL is cholesterol on the way out
LDL is a bad cholesterol while HDL is
HDL is a good cholesterol
Energy density
The amount of energy contained in a given weight or volume of a food.
A food with high energy density contains a large amount of energy in a small amount of food
Fat yields 9 kcals/gram
Fat = high energy density
How many kcals of fat do people store?
30,000 kcals +
What do cell membranes consist mostly of?
Phospholipids in the lipid-bilayer
Eicosanoid
Lipid regulatory substance with a local effect. Made from long-chain polyunsaturated fatty acids
Eicosanoids made from omega-6 linoleic acid
increassing inflammation
promoting blood clotting
constricting blood vessels
Eicosanoids made from omega-3 fat alpha-linoleic acid
Decrease inflammation
Reduce blood clotting
Dilate blood vessels
Essential Fatty Acid (EFA)
Fatty acid necessary to the operation of the body but not capable of being synthesized by the body.
Must be present in the diet.
2 EFA: linoleic acid and alpha-linoleic acid
Cornoary Heart Disease
A disease caused by atherosclerosis that results in a narrowing and thickening of arterial walls leading to insufficient blood flow to heart muscle and possibly resulting in heart attack
leading cause of death in most industrialized nations
Pathology
The study of disease processes
Atherosclerosis
The thickening and narrowing of artery walls caused by the invasion of cholesterol
Angina
chest pain caused by ischemia
Ischemia
insufficient blood flow
causes the death of tissues dependent on that blood flow for their oxygen supply
Myocardial infarction
Death of heart muscle from oxygen deprivation caued by blockage of arteries leading to the heart.
A heart attack
Stroke
Brain damage from oxygen deprivation caused by blockage of arteries to the brain
Heart disease has what kind of etiology?
multiple etiology
Etiology
The study of the cause of disease
Risk factor
Factors known to be associated with a higher risk of developing a particular disease.
Risk factors may or may not be a cause of the siease
Carcinogen
chemical which causes cancer
Average percent calories from fat
34%
