Chapter 18: Lipids

What structural feature of a fatty acid is responsible for the name omega-3 fatty acid?

(linoleic acid=omega 3 fatty acid) name comes from the endmost double bond is three carbons from the methyl end of the chain

List three diseases causes by abnormal metabolism and accumulation of sphingolipids

1) Tay- Sachs 2) Gaucher's 3) Niemann- Pick

Describe two biological roles served by the lecithins

1) important in cell membrane structure 2) form micelles to transport lipids in blood

Name two essential fatty acids, and explain why they are called essential

1) linolenic acid 2) linoleic acid body does not synthesized, must be acquired through diet

Name two groups of adrenocorticoid hormones. give a specific example of each group, and explain functions of those compounds in the body

1) mineralcorticoids ex: aldosterone: influences absorption of Na and Cl in kidney tubules 2) glucocorticoids ex: cortisol: increases glucose and glycogen in body

Describe four structural characteristics exhibited by most fatty acids

1) they a have straight-chain carbon segment with a carboxylic acid group 2) the straight chain carbon segment is 10-20 carbons long 3) there is an even number of total C atoms 4) the carbon chain may be saturated or unsaturated

What are the two categories of steroid hormones?

1)adrenocorticoid hormones 2) sex hormones

Where are cephalins found in the human body?

1)brain tissue 2) blood platelets 3) cell membranes

Name three therapeutic uses of prostaglandins

1)induce labor 2) open bronchiole tubes (treat asthma) 3) treat peptic ulcers 4) abortion in early pregnancy

What three classes of lipids are found in membranes?

1)phosphoglycerides (lecithin and cephalin) 2) sphingomyelin 3) cholesterol

What is a phosphoglyceride?

A complex lipid containing glycerol, fatty acids, phosphoric acid, and an aminoalcohol component

What is a sphingolipid?

A complex lipid containing the aminoalcohol sphingosine

What is a steroid?

A compound containing four rings fused in a particular pattern

What is an essential fatty acid?

A fatty acid needed by the body but not synthesized within the body

What is the fluid-mosaic model?

A model of membrane structure in which proteins are embedded in a flexible lipid bilayer

What is lecithin?

A phosphoglyceride containing choline

What is cephalin?

A phosphoglyceride containing ethanolamine or serine

What is a phospholipid?

A phosphorus containing lipid

What is soap?

A salt of a fatty acid often used as a cleaning agent

What is a micelle?

A spherical cluster of molecules in which the polar portions of the molecules are on the surface and the nonpolar portions are located in the interior

What is a lipid bilayer?

A structure found in membranes, consisting of two sheets of lipid molecules arrangd so that the hydrophobic portions are facing each other

What is a triglyceride or triglycerol?

A triester of glycerol in which all three alcohol groups are esterified

What is a fat?

A triglyceride that is a solid at room temperature

What structural difference in waxes and esters place waxes in a separate category?

Alcohol portion of waxes are derived from long chain alcohols rather than glycerol

What is a simple lipid?

An ester-containing lipid with just two types of components: an alcohol and one or more fatty acids

List two major functions of lipids in the human body

Cell membranes and fat

What functional group is common to all saponifiable lipids?

Esters

What symptoms might indicate the presence of gallstones in the gallbladder?

Excruciating pain, nausea, stool is gray and skin is yellow

From what general source do triglycerides tend to have more saturated fatty acids? More unsaturated fatty acids?

Fats: saturated Oils: unsaturated

Structural similarities and differences between sphingomyelins and glycolipids

Glycolipids contain carbohydrates

Where would you find membranes in a prokaryotic cell? eukaryotic cell? What function do membranes serve?

Internal and external membranes, selective barrier between living cell and its environment

What is the structural difference between lecithin and a cephalin?

Lecithin: alcohol is a choline Cephalin: alcohol is a serine or ethanolamine

Primary male sex hormone and the three primary female sex hormones?

Male: testosterone Female: Estrogens estradiol and estrone, Progesterone, and

How do phosphoglycerides differ structurally from triglycerides?

One of the -OH groups are joined by an ester linkage to a phosphoric acid, which is usually connected to another alcohol (aminoalcohol)

Why is the amount of saturated fat in the diet a health concern?

Raises blood cholesterol levels, leading to coronary heart disease

List two structural differences between sphingolipids and phosphoglycerides

Sphingolipids contain sphingosine instead of slycerol

How are testosterone and progesterone structurally similar and different?

Test. as an OH group and prog. lacks it but have en extra C=O

How are prostaglandins differentiated from each other?

The number of side chain double bonds and ring substituents

Why do athletes use anabolic steroids? what are the side effects?

They promote muscular development. Side effects include acne, liver tumors, atrophy of testes, decrease in sperm count, infertility

What is a lipid?

a biological compound that is soluble only in nonpolar solvents

What is a eukaryotic cell?

a cell containing membrane-enclosed organelles, particularly a nucleus

What is a hormone?

a chemical messenger secreted by specific glands and carried by the blood to target tissue where is triggers a particular response

What is a glycolipid?

a complex lipid containing a sphingosine, a fatty acid and a carbohydrate

What is a prokaryotic cell?

a simple unicellular organism that contains no nucleus and no membrane-enclosed organelles

What is an organelle?

a specialized structure within a cell that performs a specific function

What is a prostaglandin?

a substance derived from unsaturaed fatty acids, with hormone-like effects on a number of body tissues

What is an oil?

a triglyceride that is a liquid at room temperature

Classify the following as saponifable or nonsaponifable lipids a) sterioid b) wax c) triglyceride d) phosphoglyceride e) glycolipid f) prostaglandin

a) nonsaponifiable b) saponifiable c) saponifiable d) saponifiable e) saponifiable f) nonsaponifiable

Explain how bile salts aid in the digestion of lipids

act as a micelle to break up lipids so they can be hydrolized

What is a complex lipid?

an ester-containing lipid with more than two types of components: alcohol, fatty acids, plus others

What compound serves as a starting material for prostaglandin synthesis?

arachidonic acid

What body processes appear to be regulated in part by prostaglandins?

blood clotting, fever and inflammation, reproductive processes

How are fats and oils structurally similar? How are they different?

both contain ester groups and an alcohol portion derived from glycerol and the acid portion is furnished by fatty acids. Differ in degree of unsaturation (difference between liquid and solid)

Give another name for glycolipids; in what tissues are they found?

cerebrosides; abundant in brain tissue

What is the major component in gallstones?

cholesterol

Why is is suggested that some people restrict cholesterol intake in their diet?

high levels in blood causes atherosclerosis

What process is used to prepare margarines and cooking shortenings from vegetable oils?

hydrogenation

How does the polarity of the phosphoglycerides contribute to their function of forming cell membranes?

hydrophobic chains extend toward the inside of bilayer, hydrophilic are on the outside. proteins and nutrients can float into the bilayer

Why is the hydrogenation of vegetable oils of great commercial importance?

increases melting point

What role to estrogens and progesterone serve in preparation for pregnancy?

prepare wall of uterus for pregnancy and involved in ovum development

What role do waxes play in nature?

protective coating on fur, feathers, skin, leaves, and fruits

Explain why melting points of unsaturated fatty acids are lower than those of saturated fatty acids

unsaturated fatty acids do not pack as tightly as saturated acids

What forces hold the micelle together?

weak dispersion forces