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
