Lipids Flashcards
What are some essential lipids that must be eaten in the diet?
alpha-linolenic and linoleic acid
What are the 4 main subgroups of lipids?
Fatty acids, glycerides, non-glycerides, and complex lipids
What constitutes the fatty acid subgroup?
saturated and unsaturated
What constitutes the glycerides subgroup?
monoglycerides, diglycerides, and triglycerides or neutral glycerides and phosphoglycerides.
What constitutes the non-glycerides subgroup
Sphingolipids, steroids, waxes
What constitutes the complex lipids subgroup?
Lipoproteins
What is in the subgroup of sphingolipids?
sphingomyelins and glycolipids
What are some of the functions of lipids?
- energy
- cell membrane and structure
- hormones
- vitamins
- protection
- insulation
What is a function of the lipids in the membrane of a cell?
It can keep down inflammation
How many kilocalories are in one gram of fat?
9 kilocaleries.
What is the basic structure of a cell membrane?
- phospholipids
- shingolipids
- steriods
What are steroid hormones?
- chemical messengers
- allows tissues to communicate with each other
What are prostaglandins (hormone-like)
exert effects on cells that produce them and other cells of the body
How are vitamins carried throughout the body?
through dietary fat. Transported into cells of the small intestine in association with fat. Diets low in fat may lead to deficiencies of FSVs
Vitamin A
vision and skin, gene transcription
Vitamin D
bone health and immune function
Vitamin E
anti-oxidant and gene expression
Vitamin K
blood clotting and bone health
True or false: 4% of body fat is used as a protective function for organs
true
True or false: subcutaneous fat doe not protect against the cold
false, it does protect against the cold!`
What are the 4 groups of chain lengths present in fatty acids?
short: c4-c6
medium c8-c12
long c14-18
very long c20 or longer
Do most naturally occurring fatty acids have even number of C’s?
yes
What are the two types of nomenclature for fatty acids?
there is a common name, and a systematic name which displays how many C’s are in the molecule.
What does it mean for a molecule to be unsaturated?
there is a double bond present in the molecule and the molecule is bent. it is liquid at room temp (olive oil)
What does it mean for a molecule to be saturated?
it means that the molecule contains a line of single bonds, and each C is filled with h’s. It has a higher melting point and is solid at room temp. (butter)
what is the cis form?
the h atoms are bonded to c atoms at either end of the double are on the same side
What is the trans form?
the h atoms are on the opposite side of the double bond
12:0
laurate
dodeconoate
14:0
myristate
tetradeconoate
16:0
palmitate
hexadeconoate
18:0
stearate
octadeconoate
20:0
arachidate
eicosanoate
22:0
behenate
docosanoate
24:0
lignocerate
tetracosanate
Are there property differences in saturated and unsaturated fatty acids?
yes, see table in notes
Esterification
a fatty acid reaction where the fatty acid reacted with alcohols to form esters and water- dehydration of the carboxylic acid
Acid Hydrolysis
it is the reverse of esterfication-producing fatty acids from esters
the reaction is also called hydration because the molecule is cleaved by a water molecule.
Saponifcation
the base-catalyzed hydrolysis of an ester, it produces an ionised salt, aka soap. This soap is a long, uncharged hydrocarbon tail and a negative charged terminus. Forming micelles that dissolve oil and dirt particles.
Hydrogenation
the addition of a double bond; one can harden oil by hydrogenating it in the presence of a catalyst.
What are Eicosanoids?
Eikos is greek for 20. They arederived from the 20 carbon fatty acid families. They are involved in inflammatory and immune response.
What are the 4 families of eiconsanoids?
- prostaglandins
- prostacyclins
- Leukotrienes
- Thromboxanes
True or false: eicosanoids are stored
false, they are synthesized when needed and derived from fatty acids in the cell membrane.
When does biosynthesis of eicosanoids occur?
it is activated by trauma, cytokines, and growth factors
Where is free fatty acid oxygenated?
along any of the several pathways
What are the eicosanoid pathways
lipoxygenase (LOX) or cyclooxygenase (COX add O2
What occurs when COX or LOX are oxidized?
it releases reactive oxygen species
How is damage in by oxidation in the eicosanoid generation controlled?
by the compartmentalization of eicosanoid production and by having cellular detoxification enzymes in the pathway for production
What does the COX family generate?
prostanoids
What does the LOX family generate?
leukotrienes
What 2 drugs block COX?
Aspirin and NSAID
What are the linoleic acid inflammatory responses?
- Promote blood clotting
- promote constriction of arteries
- Increase Pain
- Increase cellular proliferation
- Depress the immune system
- Lower brain function
- increase inflammatory response
What is the N-3 or alpha linolenic acid response
- stop blood clotting
- promote dilation of the arteries
- reduce pain
- reduce cellular proliferation
- increase immune system efficiency
- improve brain function
- reduced inflammation
What happens if there is a loss of regulatory processing in inflammation?
There is excessive inflammation, and therefore irreparable host damage
What does TXA2 do?
It stands for thromboxane and it stimulates the constriction of blood vessels and platlet aggregation
What does PGI2 do?
It stands for prostacyclin and it inhibits platlet aggregation and cause the dilation of blood vessels
What are some of the functions of eicosanoids?
-blood clotting
-inflammatory response
-Respiratory tract
-reproductive system
-Gastrointestinal tract
-Kidneys
-
What does the respiratory tract do?
promotes the constriction of bronchi
What does the reproductive tract do in the case of eicosanoids?
stimulate smooth muscle or uterine contractions
What does the gastrointestinal tract do in the case of eicosanoids?
it protects the stomach lining
What is the recommended portion of fish tat should be consumed per week for omega 3?
at least two portions
What are neutral glycerides?
nonionic an nonpolar
What are phophoglycerides?
they have a polar region, the phophoryl group and nonpolar fatty acid tail.
What occurs in the esterfication of a glycerol with a fatty acid?
provides a neutral glyceride with water
What additions are required for a phosphate to be further esterfied?
serine, choline, ethanolamine, glycerol, or inositol.
Where is the C3 esterfied to?
It is esterfied to a phosphate.
What molecule do not have a glyceride?
the non-glycerides. molecules such as sphingolipids, steroids, waxes, sphingomyelins, glycolipids.
True or false: sphingolipids are derived from glycerol.
false, it is derived from a sphingosine and is a long chain, with nitrogen containing an alcohol.
What is another name for phopholipids?
sphingomyelins. They form part of the myelin sheath.
What is also called a glycosphingolipid?
cerebrosides, sulfatides, gangliosides
How is a glycosphingolipid built?
it is built on a ceramide backbone which is a fatty acid amide derivative of a sphingosine
What is a cerebroside?
- contains the sphingosine backbone attached to a fatty acid and a carbohydrate (most often glucose or galactose
- those that contain several carbohydrates are called gangliosides.
- very important for brain function.
Is a glucocerebroside a cerebroside?
yes, they have a specific function to be in the cell membrane of macrophages.
What is a sulfatide?
derived from galactocerebroside that contains a sulfate group.
What is a ganglioside?
glycolipids that have oligosaccaribe group and about 1 molecule of n-acetylneuraminic acid (sialic acid)-membranes of nerve tissues
Where is galactocerebrosides found?
almost exclusively in the membranes of brain cells
What are sterols?
- lipids containing multiple rings of carbon atoms
- crucial compoents of cell membranes and many hormones
- manufactured in our bodies and therefore do not need it in the diet.
What is one characteristic of all steriods?
all of then have a nucleus comprised of 4 fused 5C rings. For example, cholesterol, bile salts, sex hormones, cortisone.
What is the most abundant steroid?
Cholesterol- it is found in large concentrations in the brain, spinal cord, and liver. Liver is the most important site of cholesterol boisynthesis.
From what source does cholesterol come?
It is synthesized from acetic acid by multiple enzymatic reactions.
What does cholesterol serve as a precursor to?
- vitamin d3
- steroid hormones
- sex hormones
What does HDL do?
carries the cholesterol out of the blood for excretion
What does LDL do?
it carries it back for use by various body cells
Where is a cholesterol excreted?
in the liver through bile
What is artherosclerosis
it is high blood pressure, coronary heart disease and others
How can cholesterold be reduced?
- through regular exercise
- drugs such as HMG-CoA reductase inhibitors such as lovastatin and atovastatin
why are plasma lipoprotiens so important?
because they are needed to transport other lipids
What are the four classes of complex lipids?
- Chylomicrons
- VLDL
- LDL
- HDL
What are chylomicromn?
they carry triglucerides from the intestine to other tissues
What are VLDL
bind triglycerides synthesized in the liver and transport adipocytes for storage
What are LDLs?
They bind cholesterol and transport it to the peripheral tisses-regulate cholesterol levels
What are HDLs?
bound to plasma cholesterol and transport cholesterol from the peripheral tissues to the liver.
What does cholesterol help do in terms of the cell membrane?
it helps the membrane, when the body is cold, from going to a solid form
What stimulates bile production?
when fat arrives in the duodenum in fat globules
What do bile salts do?
They emulsify the fat globules into tiny droplets increasing the surface area
Was does colipase do?
is binds to TG droplets helping pancreative lipases stick to the surface and hydrolyse the ester bond between the glycerol and FA of the triglyceride. See notes for more of the process.
Where in the cell are triglycerides stored?
near the mitochondria
What occurs when cells need energy and need to use TG?
TG are hydrolyzed to release FA that are transported into the matrix space of the mitochondria. Then FA are oxidized and ATP is produced.
What is beta oxidation
it is the breakdown of fatty acids to acetyl CoA
What occurs prior to fatty acid degradation?
FA are activated by coenzyme A.
What is the product for each cycle of beat oxidation
1 FADH2 (2 atp) 1 NADH (3 atp)
Where does the activation reaction for beta oxidation occur?
in the cytostol
What is the pathway for the activation reaction?
refer to notes
What is the first step in beta-oxidation?
oxidation. remove a pair of hydrogen atoms from the FA.
- this reduces FAD to FADH2 (producing 2 ATP)
- rx catalyzed by acyl-coA dehydrogenase , forming a C-C double bond
What is the second step in beta oxidation?
Hydration.
- H2O is added across the double bind
- beta carbon is hydroxylated
- rx catalyzed by enoyl-coA hydrase
What is the third step in beta oxidation?
- Oxidation
- Hydroxyl group of b-carbon now hydrogenated
- NAD+ reduced to NADH (produced 3 ATP
- L-beta hydroxyacyl-CoA dehydrogenase catalyzes this reaction
What is the fourth step in beta-oxidation?
- catalyzed by thiolase
- cleavage and release of acetyl coa by thiolysis
- thiol is instered between c-2 and c-3
- produces: acetyl coA molecule &a FA (acyl coA molecule) that is two carbons shorter.
How many ATP are produced from the complete oxidation of a stearic acid?
146
What are ketone bodies produced from?
from acetyl co-a
What are the 3 forms of ketone bodies?
- acetone
- acetoacetic acid
- beta-hydroxybutyric acid
