5.2 Types of Lipid Molecules Flashcards
What are we typically referring to when we use the word ‘fat’?
triglycerides
What are triglycerides?
The major form of lipid in food and in the body. They consist of three fatty acids attached to a glycerol molecule.
What do fatty acids help to determine?
The physical properties and health effects of the triglycerides we consume
What are fatty acids?
Organic molecules made up of a chain of carbons linked to hydrogen atoms with an acid group at one end.
What are phospholipids?
Types of lipids containing phosphorous. The most common are the phosphoglycerides, which are composed of a glycerol backbone with two fatty acids and a phosphate group attached.
What are sterols?
Types of lipids with a structure composed of multiple chemical rings.
Chemical Formula of triglycerides.
3 fatty acids + glycerol = triglyceride + 3 Water [H from glycerol and OH from fatty acid combined)
What determines the physical properties of a fatty acid?
The length of the carbon chain and the type and location of the bonds between the carbon atoms
How can describe a fatty acid structurally?
It is a chain of carbon atoms with an acid group (COOH) on one end and a methyl or omego end (CH3).
Describe saturated fatty acids.
Contain no carbon-carbon double bonds, Red meat, butter, cheese, and whole milk.
Describe unsaturated fatty acids.
Include monounsaturated and polyunsaturated fatty acids.
Polyunsaturated fatty acids.
Contain more than one carbon-carbon double bond.
Monounsaturated fatty acids.
Contain one carbon-carbon double bond. Canola, olive oil, and peanut oils, as well as nuts and avocados.
Omega-6-fatty acids
The first double bond occurs between the sixth and seventh carbon atoms (from the omega end). Corn oil, safflower oil, soybean oil, and nuts
Omega-3-fatty acids
The first double bond occurs between the third and fourth carbon atoms, the fatty acid is an omega-3 fatty acid. Flaxseed, canola oil, and nuts
How many carbons do most fatty acids found in plants and animals, including humans, contain?
14 and 22 carbons
How long are short-chain fatty acids?
4-7 carbons in length
In what state do short-chain fatty acids remain in colder temperatures?
Liquid (like those in milk)
How long are medium-chain fatty acids?
8-12 carbons
In what state do medium-chain fatty acids remain in colder temperatures?
Solidify in the refrigerator but liquid at room temperature (like cococunt oil)
What is the melting point of coconut oil?
25° C
How long are long-chain fatty acids?
More than 12 carbons
In what state do longer-chain fatty acids remain at room temperatures?
Solid (like beef fat)
What is the melting point of beef fat?
50° and 70°C
What is saturated fatty acid?
A fatty acid in which the carbon atoms are bound to as many hydrogens as possible and which, therefore, contains no carbon-carbon double bonds.
What are the most common saturated fatty acids?
palmitic acid (16 carbons), steric acid (18 carbons)
What are some plant sources of saturated fatty acids?
palm oil, palm kernel oil, and coconut oil (known as tropic oils)
What is the most common monounsaturated fatty acid in our diet?
oleic acid in olive and canola oils, beef
What is the most common polyunsaturated fatty acid in our diet?
linoleic acid in corn, safflower, and soybean oils
What makes a fatty acid more likely to be liquid at room temperature?
the more unsaturated bonds it contains
What are examples of omega-3-fatty acids?
Alpha-linolenic acid, found in vegetable oils, and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in fish oils
What are examples of omega-6-fatty acids?
Linoleic acid, found in corn and safflower oils, and arachidonic acid, found in meat and fish
What is the major omega-6-fatty acid found in the American diet?
Linoleic acid
What processes are omega-3 and omega-6 fatty acids in the diet important in?
blood pressure regulation, blood clotting, immune function
Increasing the intake of omega-3-fatty acids, especially EPA and DHA found in fish, has been associated with what?
Reduced deaths from cardiovascular disease
What are the omega-3 fatty acids in fish?
Mainly EPA and DHA
What are the omega-6 fatty acids in plant food?
Mainly alpha-linoleic acid
What is a trans fatty acid?
An unsaturated fatty acid in which the hydrogen atoms are on opposite sides of the double bond.
In which type of fatty acid does the orientation of hydrogen atoms around the double bond cause a bend in the carbon chain?
cis fatty acid
Where is a lot of trans fat derived from?
partial hydrogenation of vegetable oils
found in - stick margarine and vegetable shortening
& They are also used to lengthen shelf life in other processed foods such as cookies, crackers, breakfast cereals, and potato chips
What is hydrogenation?
The process whereby hydrogen atoms are added to the carbon-carbon double bonds of unsaturated fatty acids, making them more saturated.
Describe conjugated linoleic acid.
What are the properties of tryglicerdies?
Triglycerides may contain any combination of fatty acids: long, medium, or short chain; saturated or unsaturated; cis or trans.
The types of fatty acids in triglycerides determine their texture, taste, and physical characteristics.
What are phospholipids?
Phospholipids are lipids attached to a chemical group containing phosphorus called a phosphate group
What are phosphoglycerides?
A class of phospholipid consisting of a glycerol molecule, two fatty acids, and a phosphate group.
What is significant about the fatty acid and phosphate ends of a phosphoglyceride?
the fatty acid end is soluble in fat while the phosphate end is water-soluble. Likewise, phosphoglycerides can mix with both water and fat.
What are emulsifiers?
Substances that allow water and fat to mix by breaking large fat globules into smaller ones.
What is an example of emulsifiers?
egg yolks, which contain phosphoglycerides, function as an emulsifier in cake batter, where they allow the oil and water to mix
What is a lipid bilayer?
Two layers of phosphoglyceride molecules oriented so that the fat-soluble fatty acid tails are sandwiched between the water-soluble phosphate-containing heads.
How do phosphoglycerides act as emulsifiers in food?
they can surround droplets of oil, allowing them to remain suspended in a watery environment
What is a lecithin?
A phosphoglyceride composed of a glycerol backbone, two fatty acids, a phosphate group, and a molecule of choline.
What are some natural sources of lecithin?
Eggs and soybeans
Where else does the food industry use lecithin?
an additive in margarine, salad dressings, chocolate, frozen desserts, and baked goods
What are some uses of lecithin in the body?
cell membranes, synthesize the neurotransmitter acetylcholine
What is cholesterol?
A lipid that consists of multiple chemical rings and is made only by animal cells.
Where is more than 90% of the cholesterol in our body found?
cell membranes
What are some uses of cholesterol?
It can synthesize Vitamin D in the skin; cholic acid, a component of bile called a bile acid; some hormones such as testosterone and estrogen; and cortisol
Is cholesterol an essential nutrient?
It is needed in the body but because the liver makes it, it is not essential.
What are the beneficial effects of plant sterols?
help reduce cholesterol levels in the blood by decreasing cholesterol absorption from the diet and increasing the excretion of bile acids, which are synthesized from cholesterol, in the feces
