Chapter 6: Lipids Flashcards
most widely occuring types of lipids
- fats
- oils
thick layers of fat help __ polar bears against the effect of low temperatures
insulate
where is the characterization of lipids based on
solubility characteristics
oranic compound found in living organisms that is insoluble (or only sparingly soluble) in water but soluble in nonpolar solvents
lipids
where is the word lipd from
Greek lipos = fat or lard
where is lipids soluble
nonpolar organic solvents
Four main types of lipids
- fatty acids
- glycerides
- nonglyceride lipids
- complex lipids
fatty acids
- saturated
- unsaturated
glycerides
- neutral glycerides
- phosphoglycerides
nonglyceride lipids
- sphingolipids
- steroids
- waxes
sphingolipids
- sphingomyelins
- glycolipids
complex lipids
lipoproteins
are found in many types of lipids
fatty acids
Biological functions of lipids
- energy source
- cell membrane structural components
- hormones
- vitamins and vitamin absorption
- protection
- insulation
energy source
triacylglycerols
when oxidized, how many kilocalories of energy do lipids release
9 kilocalories
kilocalories of energy released by carbohydrate
4 kcal
fat cells
adipocytes
make up the basic structure of all cell membranes
- phospholgycerides
- sphingolipids
- steroids
- play an important role in clotting of blood and in structure of a membrane
- allow transport of enzymes and is a major component of membrane
Phosphoglycerides
- enriched in the Central Nervous System (CNS) and display multiple biological functions
- participate in tissue development, cell recognition and adhesion, and act as receptors for toxins
Sphingolipids
- dominant sphingolipid in membranes of mammalian cells
- specifically enriched in the plasma membrane, the endocytic recycling compartment, and the trans Golgi network
Sphingomyelin (SM)
- reduce the fluidity of the cell membrane
- function as signaling molecules within the cell
Steroids
combination of phospholipids and proteins that reduces surface tension in the alveoli of the lungs
pulmonary surfactant
small, thin-walled air sacs in the lungs
alveoli
what do pulmonary surfactants allow
- efficient gas exchange across membranes
- oxygen and carbon dioxide can easily diffuse
pulmonary surfactant is not produced until early in the __ __ of pregnancy
6th month
what do premature babies born before they have begun secretion of natural surfactant suffer from
respiratory distress syndrome (RDS)
administered directly into the trachea of babies with respiratory distress syndrome (RDS)
artificial surfactant
critical chemical messengers that allow tissues of the body to communcate with each other
steroid hormones
exert strong biological effects on both the cells that produce them and other cells of the body
prostaglandins
can reduce pain, fever and other types of inflammation by inhibiting the COX enzymes
Non-steroidal anti-inflammatory drugs (NSAIDs)
precursor of prostaglandins
arachidonic acid
physiological stimuli
COX1
infection, injury
COX2
COX1
protective prostaglandins
COX2
inflammatory prostaglandins
protective prostaglandins
- stomach mucosa
- platelet stickiness
inflammatory prostaglandins
- pain
- fever
- inflammation
lipid-soluble vitamins
- A
- D
- E
- K
- important for normal vision, the immune system, reproduction, and growth and development
- helps your heart, lungs, and other organs work properly
Vitamin A
- essential for bone strength and may be good for supporting the immune system and other functions
Vitamin D
- main role is to act as an antioxidant, scavenging loose electrons—so-called “free radicals”—that can damage cells
- enhances immune function and prevents clots from forming in heart arteries
Vitamin E
- group of vitamins that the body needs for blood clotting, helping wounds to heal
- may help keep bones healthy
Vitamin K
fat serve as a __ __, or protective layer for the vital organs
shock absorber
percent of body fat reserved for protection
4%
hormones
- steroid hormones
- eicosanoids
- signaling molecules that play a unique role in innate immune responses
- allow the innate immune cells to respond rapidly to bacterial invaders
Eicosanoids
serves to insulate the body from extremes of cold temperatures
subcutaneous fat
Two categories of lipids based on hydrolysis
- Saponifiable lipids
- Nonsaponifiable lipids
hydrolysis reaction that occurs in basic solution
saponification reaction
saponifialbe lipids
- triacylglycerols
- phospholipids
- sphingoglycolipids
- biological waxes
nonsaponifiable lipids
- cholesterol
- steroid hormones
- bile acids
- eicosanoids
a lipid is any substance that is __ in water and __ in nonpolar solvents
- insoluble (water)
- soluble (nonpolar solvents)
the saponification/nonsaponification classification system for lipids is based on
lipid behavior in basic solution
- long-chain monocarboxylic acids
- generally contain an even number of carbon atoms as a consequence for their biosynthesis
- rarely found in nature but rather part of more complex lipid structure
fatty acids
one that contains at least one carbon-to-carbon double bond
unsaturated fatty acid
18-carbon unsaturated fatty acid
oleic acid
the double bonds found in almost all naturally occuring lipids is __ __
cis-configuration
cis-configuration puts a rigid __ __ in the chain
30° bend
fatty acid with a carbon chain with one carbon-carbon double bond present
monounsaturated fatty acid (MUFA)
fatty acid with a carbon chain in which two or more carbon-carbon double bond
polyunsaturated fatty acid (PUFA)
up to __ double bonds are found in biochemically important PUFAs
six
MUFAs are usually __ acids and first two additional double bonds in PUFAs are generally at __ and __ locations
- Δ9
- Δ12
- Δ15
PUFA of arachidonic acid
20:4(Δ5,8,11,14)
exist when double-bond position is specified relative to the methyl (noncarboxyl) end of the fatty acid carbon chain
families of unsaturated fatty acids
families of unsaturated fatty acids exist when double-bond position is specified relative to the __ __ of fatty acid carbon chain
methyl (noncarboxyl) end
an unsaturated fatty acid with its endmost double bond three atoms away from methyl end
Omega-3 FA
unsaturated fatty acid with its endmost double bond six carbon atoms away from its methyl end
Omega-6 FA
statement regarding fatty acids
rarely found in free state in nature
example of members of pair polyunsaturated fatty acids
- 18:2 acid
- 18:3 acid
example of omega-6 fatty acid
CH3 – (CH2)4 – CH==CH – (CH2)8 – COOH
double bond present in monounsaturated fatty acid almost always in
cis-configuration