Lipids

What are Linoleic fatty acids?

1. Omega-6 2. Sources include vegetable oils, such as sunflower and safflower

How many kcal per gram of fat?

9 kcal

How are trans fatty acids both similar to and different from saturated and unsaturated fatty acids?

A trans fatty acid is similar to a saturated and unsaturated fatty acid in that it is made up of carbon and hydrogen, and it contains a methyl and carboxylic acid end. However, a saturated fatty acid has the maximum possible number of hydrogen atoms attached to every carbon atom, and mono- and polyunsaturated fatty acids lack a pair of hydrogen atoms in the middle of the fatty acid chain. Although the trans fatty acids are chemically "monounsaturated" or "polyunsaturated" they are in a configuration called trans (mono- and polyunsaturated fatty acids take the cis formation). The difference between cis and trans is that the two hydrogen atoms are on the same side of the double bond (cis), not on opposite sides (trans). This configuration affects the shapes of the molecules. In a cis configuration, the double bond creates a kink in the fatty acid. In the trans configuration, there is no kink. Therefore, a trans-fatty acid is structurally similar to a saturated fatty acid (which has no kink, either).

Describe the structure of a fatty acid. What do these also make up?

A type of lipid, but they are also the primary components of both triglycerides and phospholipids. Fatty acids consist of a chain of carbon atoms with hydrogen atoms attached to each carbon atom (a hydrocarbon chain): a carboxyl group attached to one end of the fatty acid chain, and a methyl group at the other end (three hydrogens bonded to a carbon atom—also called the "omega" end of the fatty acid).

What is LDL?

VLDL is converted into LDL which primarily carries cholesterol to all cells in the body

What are the two essential fatty acids? Are these suturated or unsaturated? Bespecific

linoleic acid and linolenic acid- polyunsaturated

Where is cholesterol synthesized?

liver

Is cholesterol an essential nutrient?

no b/c our body produces it.

What is VLDL?

transports triglycerides from liver to muscle and adipose tissues

What is a chylomicron?

type of lipoprotein that transports dietary fats and cholesterol from intestines to muscle and adipose tissue

What determines the function in the body of a fatty acid?

Both properties, degree of saturation, and chain length determine their function in the body and role in health and disease.

What is the structure of sterols? What is the most widely discussed sterol? What is it needed for?

Chemically, sterols are complex lipids with four interconnected carbon rings with a hydrocarbon side chain. The most discussed sterol is cholesterol. A molecule with varied functions, cholesterol is a critical component of our cell membranes and is also needed as a precursor for the synthesis of bile acids, vitamin D, and steroid hormones such as estrogen and testosterone, but it does not provide any energy.

List the four major categories of dietary lipids.

Fatty acids, triglycerides, sterols, and phospholipids

What elements make up​ lipids? Are lipids generally soluble or insoluble?

H, C, small amount of O. Insoluble.

What are linolenic fatty acids?

Linolenic acid is an omega-3 fatty acid—with the first double bond of the carbon chain located in the third position. Like phospholipids and sterols, it's a structural component of cell membranes. Linolenic acid is found in walnuts, flax seeds, soy, canola oil, and chia seeds.

What is the structure of a triglyceride? What do they supply when consumed?

Lipids made up of three fatty acid chains bound to one glycerol, a small three-carbon molecule that makes up the glycerol backbone of each triglyceride. The fatty acid chains form the "tail" of the triglyceride. All triglycerides are composed of a mix of short-chain, medium-chain, and long-chain fatty acids. They seldom contain exclusively one type of fatty acid. Triglycerides in foods supply energy and may also carry certain fat-soluble vitamins, such as vitamins A, D, E, and K. Since triglycerides consist of three fatty acids, they can provide essential fatty acids, the fatty acids our bodies need but cannot synthesize in sufficient amounts, and so must be obtained through our diets.

Are phospholipids an essential nutrient?

No

Describe the structure of phospholipids. What is it a primary component of?

Phospholipids are similar to triglycerides in structure: they have a glycerol backbone, but with two rather than three attached fatty acids. Attached at the third position is a phosphate group and one of several water-soluble "head-groups." Together the glycerol backbone, the phosphate, and the head group create a water-soluble head on the phospholipid, while the fatty acid "tails" at the other end are soluble in lipids but not in water.

What is HDL?

Picks up cholesterol from body tissue and returns it to liver.

What are the four degrees of fatty acid categorization? What do these chains look like? Are they solid or liquid at room temperature? What food sources do they come from?

Some fatty acids are saturated, with hydrogen atoms filling every possible bond with carbon atoms. Saturated fatty acids are relatively solid at room temperature, and most commonly found in animal products (such as meats and dairy), as well as some vegetable products (such as coconut oil, palm kernel oil, palm oil, and cocoa butter). The rest are unsaturated, with less hydrogen and one or more double bond (or point of unsaturation) between carbon atoms, and are generally liquid at room temperature. Unsaturated fats are found most abundantly in plant foods, such as seeds, nuts, grains, and most vegetable oils. Fatty acids with one point of unsaturation are called monounsaturated fatty acids (abundant in olive and canola oils and nuts); those with more than one point of unsaturation are called polyunsaturated fatty acids (abundant in corn, safflower, sunflower, sesame, and soybean oils). The arrangement of the hydrogen atoms on either side of the double bonds can be in either a "cis" or a "trans" orientation, which has important health implications, as will be discussed later in the chapter.