Lipids - Chapter 6 Flashcards Preview

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Flashcards in Lipids - Chapter 6 Deck (98)
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Lipids

Substances soluble in organic solvents

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Hydrophobic

"Water-hating" "water-fearing"

Repelled by water

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Lipophillic

Lipids are lipophillic

"fat loving"

attracted by lipid

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Where is most of the lipid stored?

In the bodies of animals

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Organic

  • A complex chemical containing carbon in its structure. 
  • Often formed in a bioogical process

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What form is most inorganic carbon in?

Carbon dioxide in the atmosphere

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Three kinds of lipids

  1. Triglycerides
  2. Phospholipids
  3. Sterols

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Triglyceride

  • A type of lipid formed by three fatty acids arrayed on a glycerol backbone
  • Most fats occur in the triglyceride form

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Phospholipid

  • A type of lipid similar to a triglyceride in which one of the fatty acids is replaced by a phosphorous-containing compound

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Sterol

  • A type of lipid with a multiple ring structure, such as cholesterol

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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

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Methyl

  • the omega end
  • the chemical group -CH3

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Carboxyl

  • alpha end
  • the chemical group -COOH

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Valence

The characteristic number of chemical bonds formed by a particular chemical element

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Valence of hydrogen

1

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Valence of oxygen

2

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Valence of carbon

4

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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

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Butryic (4C) Caprylic (8C) and stearic (18C)

Acids that are typical of saturated fatty acids

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Saturated fats worst

Worst dietary contributor to the development of heart disease

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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

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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

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Oleic acid (18C)

Makes up most of olive oil (a MUFA)

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Saturated fats raise what?

Blood cholesterol

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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

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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

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18:3 fatty acid

18 carbons with 3 double bonds

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Examples of saturated fatty acids

Coconut oil

Butter

Palm oil

Lard or beef fat

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Examples of monounsaturated fatty acids

Olive oil

Canola oil - also rich in omega-3

Peanut oil

Soybean oil - also rich in omega-3

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Linoleic acid

An 18:2 omega-6 polyunsaturated fatty acid

An essential fatty acid

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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

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Eicosapentanoic acid

A 20:5 omega-3 polyunsaturated fatty acid.

Found in fish

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Docosahexanoic acid

A 22:6 omega-3 polyunsaturated fatty acid

Found in fish

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Omega-3's are mainly:

Fish oils

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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

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Alpha-linolenic acid

An 18:3 omega-3 fatty acid.

Essential fatty acid

Found in flax, canola, and soy oils

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Fats consist of a mixture of fatty acids but one particular fatty acid usually dominates

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Increasing saturation

raises the melting point of a fat

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Saturated fats get

stiff at low temperatures

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Cold climate plants

Are highly polyunsaturated

Corn, soybeans, and sunflowers

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Warmer climate plants

Maintain fluidity using monounsaturated fats

olives

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Really warm climate plants

Use saturated fats

tropical oils, palm, palm kernel, and coconut

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Percent of triglycerides

98 percent of the time, fatty acids are assembled into triglycerides

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What are triglycerides made from?

Three fatty acids arranged on a glycerol backbone

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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

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cis-bond

same

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trans bond

across

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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.  

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Rancidity

The off-flavor caused by oxidation of lipids

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Peroxidation

The process by which free radical oxygen attacks a double bond in a fat

Causes rancidity

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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

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Antioxidant

Substance which protects cellular components against oxidation by reacting with free radical oxygen itself

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Examples of antioxidants

Vitamin A

Vitamin C

Vitamin E

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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

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Cholesterol

Sterol with multiple ring structure, synthesized by the body and used to manufacture steroid hormones and other substances

Found only in animal foods

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Phospholipids are important

in cell membrane structure, and are used in food processing as emulsifiers

example: Licithin

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Examples of sterols

Many hormones - estrogen and testosterone = steroids

Vitamin D

cholesterol

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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

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Mouthfeel

Forming the texture and the feel of the food when we eat it

Fat contributes to this

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Lipids are not

water soluble

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Monoglyceride

A single fatty acid attached to glycerol

Formed by digestion of triglyceride

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Chylomicron

Large lipoprotein that transports lipid from the gut, delivering dietary triglyceride to body cells and cholesterol to the liver

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Lipoprotein Lipase

Enzyme attached to artery wall that breaks down triglyceride from lipoprotein into free fatty acids and glycerol

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endogenous

made within the body

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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

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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

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Primary site for digestion and absorption of lipids

Small intestine

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How much of ingested fat is excreted in feces?

5%

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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

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Receptor

Protein on a cell membrane which recognizes and binds a specific substance in the blood, such as LDL or estrogen

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plaque

Arterial lesion formed by deposit of cholesterol

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the good cholesterol

HDL

Protective against heart disease

pulls cholesterol out of the arterial plaques

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Short and simple: chylomicrons

Bring dietary lipids from the gut and deliver triglyceride throughout the body

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Short and simple: VLDL

formed in the liver

delivers triglyceride synthesized in the liver

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Short and simple: LDL

Delivers cholesterol throughout the body for vital uses and to clog your arteries

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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

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LDL is cholesterol on the way into the body, while HDL

HDL is cholesterol on the way out

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LDL is a bad cholesterol while HDL is

HDL is  a good cholesterol

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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

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How many kcals of fat do people store?

30,000 kcals +

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What do cell membranes consist mostly of?

Phospholipids in the lipid-bilayer

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Eicosanoid

Lipid regulatory substance with a local effect.  Made from long-chain polyunsaturated fatty acids

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Eicosanoids made from omega-6 linoleic acid

increassing inflammation

promoting blood clotting

constricting blood vessels

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Eicosanoids made from omega-3 fat alpha-linoleic acid

Decrease inflammation

Reduce blood clotting

Dilate blood vessels

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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

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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

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Pathology

The study of disease processes

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Atherosclerosis

The thickening and narrowing of artery walls caused by the invasion of cholesterol

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Angina

chest pain caused by ischemia

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Ischemia

insufficient blood flow

causes the death of tissues dependent on that blood flow for their oxygen supply

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Myocardial infarction

Death of heart muscle from oxygen deprivation caued by blockage of arteries leading to the heart.

A heart attack

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Stroke

Brain damage from oxygen deprivation caused by blockage of arteries to the brain

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Heart disease has what kind of etiology?

multiple etiology

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Etiology

The study of the cause of disease

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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

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Carcinogen

chemical which causes cancer

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Average percent calories from fat

34%

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