Lipids (mini-test) Flashcards
Are lipids fats?
no
are fats completely hydrophobic?
yes
90% of lipids in food are ________________
fats/triglycerides
What are the functions of lipids?
-store molecules for energy (9 cal per g in fats, 4 cal per g in protein/carbs, lipids are stored in adipose tissue and is insoluble in water while soluble in organic solvents and lipids, we have endless power to store fat)
-structural components of cellular membranes (phospholipid bilayer)
-hormones and vitamins (cholesterol is an important precursor molecule for the synthesis of vitamin D and the steroid hormones like cortisol and estrogen)
-protective molecules (lipids help prevent damage to organs and keep you from getting wet bc of a waxy texture, and helps us insulate)
T/F: there are good and bad lipids
true
What are the 3 major groups of fatty acids?
1) saturated FA
2) unsaturated FA
3) trans fat
What is a fatty acid?
a carboxylic acid with a long carbon-hydrogen tail, which is either saturated or unsaturated
Which fatty acid group has the highest melting temp?
saturated FA
What does saturated FA mean?
saturated with hydrogens, and theres only single bonds
Are saturated FAs solid or liquid at room temp?
solid
What are the food sources for saturated fat?
-animal fat (lard)
-real butter
Are saturated FAs high or low energy?
high energy compared to unsaturated FAs (this is bc saturated FAs have more hydrogens)
Which fatty acid type naturally has a double bond or multiple double bonds?
cis unsaturated fatty acids
What are unsaturated fatty acids?
-FA with a double bond, or multiple double bonds
-if its a cis configuration then its natural and there is a C=C that is kinked because the hydrogens bonded to the carbons are on the same side
-if its a trans configuration then its unnatural/bad for you, it has double bond but is NOT kinked because the hydrogens are on opposite sides, so a trans unsaturated FAs looks similar to a saturated FA
What is a mono-unsaturated FA (MUFA)? What are its characteristics and where is it found?
-1 double bond in the FA
-liquid at room temp but will become solid in cold temp
-olive oil is a MUFA
What are poly-unsaturated FAs (PUFAs)? What are its characteristics and where is it found?
-FA has more than 1 double bond
-liquid at room temp and in cold
-found in fish oil and veggie oil (veggie is cheaper)
What are the characteristics of trans fat? How is it formed?
-double bond(s) that have no kink bc H on opposite sides
-all trans fat is solid at room temp
-unnatural
-formed from partial hydrogenation (hydrogen gas) which causes the unsaturated fat to transition from a cis form to a trans form
-hydrogenation causes an increase in energy because of an increase in hydrogens, so it will become a solid that is spreadable like margarine
-the increase in hydrogens increases the melting temp because energy is increased
-trans fat increases LDL which ultimately increases heart disease
-trans fat is the most stable FA type, so it has an increased shelf life compared to anything else and prevents rancid
Which fatty acid is 18:2?
linoleate, also called linoleic acid
Is linoleate an omega 3, 6, or 9?
omega 6
Linoleate is rich in which food?
veggie oil
What are the 3 essential fatty acids?
1) linoleate (also called linoleic acid)
2) linolenate (also called linolenic acid)
3) arachidonate (also called arachidonic acid)
Which fatty acid is 18:3?
linolenate (also called linolenic acid)
Is linolenate (also called linolenic acid) an omega 3, 6, or 9?
omega 3
linolenate (also called linolenic acid) is rich in which food?
fish oil
butter/animal fat is rich in which 2 fatty acids?
palmitate and stearate
note: a grass-fed cow would have more stearate, while a grain fed cow would have more palmitate
What is the average number of carbons for FAs?
12-20 (usually even numbers)
Are fatty acids amphipathic?
yes
Which fatty acid is 16:0? What do these numbers mean?
-palmitic acid, also called palmitate
-its a saturated FA (SFA)
-the 16 is the number of carbons and the 0 is the number of double bonds (this is known as the delta system)
Which FA is the most abundant in the body/food?
palmitic acid, also called palmitate (it increases blood cholesterol levels and increases risk of heart disease)
Which FA is 18:0?
stearic acid, also known as stearate (its a saturated FA)
Which FA is 18:1, also known as C18:1, C18:1(9) or 18:1 delta 9? What do these numbers mean?
-oleic acid also known as oleate
-its a mono unsaturated FA
-the carbons and double bond are a part of the delta system, the delta showing which carbon has the double bond (smallest number is the one C on left)
Oleic acid also known as oleate is rich in which foods?
avocado and olive oil
Which FA is C20:4, also known as C20:4 (5, 8, 11, 14), or 20:4 delta 5, 8, 11, 14? What do these numbers mean?
-arachidonic acid, also known as arachidonate
-its a poly-unsaturated fatty acid
-the carbons and double bonds are a part of the delta system BUT because it has multiple double bonds it can be calculated which omega it is, per the omega system
-so in this case you take the total carbons number and subtract it by the last C double bond number, which here it would be 6, so this is an omega 6
arachidonic acid, also known as arachidonate is derived from which other FA?
linoleate (also called linoleic acid)
Which FA is conditionally essential?
arachidonic acid, also known as arachidonate
What are the lipid soluble vitamins that are stored in lipids and are a part of food?
vitamin K, A, D, and E “KADE”
note: having a fat free diet can cause a deficiency in these
What are the good and bad fats?
good= omega 3 and 9
bad= omega 6
Omega system is for ___________________ FAs only
unsaturated (with more than one double bond!)
T/F: veggie and fish oil have a stable double bond
FALSE its unstable, especially in the summer with warmer weather
its unstable, best to eat fish in cold weather, or cold water fish
also note: more double bonds= more stability (like trans fat is the most stable)
Where can you find high quality good fat?
-grass fed beef
-fish
-olive oil
Which FAs pack closely together?
saturated FA
Which FAs have the highest melting temp?
saturated FAs
Are saturated FAs more or less fluid compared to other FAs?
less fluid
Which FAs do not pack closely together?
unsaturated FAs
Are unsaturated FAs more or less fluid compared to other FAs?
more fluid
Do unsaturated FAs have higher or lowering melting temperatures compared to other FAs?
lower melting temp
Which FA is the most stable?
trans fat
Rank the FAs in highest to lowest melting temp
-highest= saturated FAs
-trans fat
-mono-unsaturated FAs
-lowest= poly-unsaturated FAs
What affects melting point and fluidity in FAs?
chain length and degree of double bond(s)
Rank the FAs in highest stability to lowest stability
-highest= trans fat
-saturated FAs
-mono-unsaturated FAs
-lowest= poly-unsaturated FAs
What type of FA is coconut oil?
short chain FA (SCFA), will be liquid in warm temps and solid in cold temps
What is the 1st class of lipids?
monoglycerides, diglycerides, and triglycerides
What do triglycerides consist of?
3 fatty acids with a glycerol backbone
What are the other names for triglyceride?
triacylglycerol (TAG), or fat
What is the function of triglycerides?
they’re storage lipids that are non-polar/completely hydrophobic
What breaks down triglycerides?
lipases
How do ester bonds break?
hydrolysis reaction will use water to break ester bond
What is the 2nd class of lipids?
phosphoacylglycerols, also called phospholipids
What do phosphoacylglycerols, also called phospholipids consist of?
phosphohead, 2 FAs, and glycerol backbone
What are the functions of phosphoacylglycerols, also called phospholipids?
-membrane structure (amphipathic)
-intracellular signaling (choline and poly-unsaturated FAs are precursors for eicosanoids)
-phospholipids make up phospholipid bilayer, liposome (2 layers), micelle (one layer)
What breaks phospholipids? What does X represent?
phospholipases:
-phospholipase A1 breaks the 1st FA
-phospholipase A2 breaks the 2nd FA
-phospholipase C removes phosphohead
-phospholipase D removes the X attached to phosphohead
X can be basically anything
-if its hydrogen then the whole molecule is called phosphatidyl acid
-if its choline, then its called lecithin or phosphatidyl choline
What is the simplest phospholipid?
phosphatidyl acid (H attached to phospholipid)
What is the most abundant phospholipid on cell membrane?
phosphatidyl acid (H attached to phospholipid)
note: if she asks about most abundant hydrophobic part then its just the tail, and if she asks about hydrophilic part then its just the phosphohead
Which phospholipid is important for production of ACh and is essential for memory?
lecithin, also called phosphatidyl choline (choline attached to a phospholipid)
Which enzyme is rich in the venom of poisonous snakes? What does it do?
phospholipase A2
-this enzyme cleaves carbon 2 and will create lysolecithin which acts like a detergent that disrupts and dissolves cell membranes in RBCs
-this causes hemolysis, oxygen deprivation, and eventually death
Which 2 classes of lipids have a glycerol backbone?
triglycerides and phospholipids
What is the 3rd class of lipids?
sphingolipids
What are sphingolipids?
-C1 has an OH
-C2 has an amino group
-C3 has an OH
-different molecules can bind to either the OH or amino group, it depends, sometimes multiple things bind
-a FA can only bind at the amino group, and only 1 FA can do this, this is a peptide bond (not an ester like in triglycerides or phospholipids)
-the backbone here is a sphingosine, not a glycerol
Are sphingolipids amphipathic?
yes bc of OH group
The sphingomyelin is the only class of sphingolipids that is also ____________. It represents 85% of all sphingolipids and typically makes up 10-20% of plasma membrane lipids
phospholipid
How are sphingolipids broken down?
within lysosomes
If X is a hydrogen on a sphingolipid, what is it now called?
ceramide
If X is a phosphocholine on a sphingolipid, what is it now called?
sphingomyelin
What is the most abundant sphingolipid? Why?
sphingomyelin bc its the major lipid of myelin sheath (insulates axons)
If X is a single sugar on a sphingolipid, what is it now called?
cerebroside (its a glycolipid)
If X is an oligosugar on a sphingolipid, what is it now called?
ganglioside (its a glycolipid)
Lack of lipids can cause decreased myelin sheaths on neurons. What can this cause?
neuropathy
What are 2 lysosomal diseases caused by improper degradation of sphingolipids?
-tay-sachs disease
-niemann-pick disease
What is Tay-Sachs disease? What is it caused by? What are the symptoms?
-harmful quantities of gangliosides accumulate in the brain and eventually leads to premature death of cells
-causes progressive deterioration of mental and physical abilities (usually starts at 6 months and child on average only lives till 4 y/o)
-caused by insufficient activity of hexosaminidase A (enzyme found in lysosomes that hydrolytically breaks down glycolipids)
-symptoms: loss of motor control, can no longer sit or crawl, loss of muscle strength, mental retardation, loss of sight, hearing, and even swallowing abilities
-the tell-tale sign is a “cherry red” macula in the retina
-can be diagnosed by measuring gangliosides in blood or the enzyme
What is Niemann-Pick disease? What is it caused by?
-sphingomyelin accumulates in lysosomes
-caused by sphingomyelinase mutation (loss of activity mutation, no longer breaking down sphingomyelins)
-can be fatal to toddlers depending on severity
-people with mild forms can live into teens or young adulthood
-harmful quantities of lipids accumulate in the liver, lungs, BM, spleen, and brain
-symptoms are related to where it accumulates
What is saponification?
the process to make soap
the first 3 classes of lipids can be used- triglycerides, phospholipids, and sphingolipids
What is the 4th class of lipids?
cholesterol derivatives, helps make hormones, bile salt, vitamin D, etc
What is the structure of cholesterol? Can it be broken down?
-4 fused rings
-OH on C3
-amphipathic because of OH group
-rings cannot be broken down, so its not an energy force
-4 fused rings are rigid
T/F: cholesterol is amphipathic while cholesterol ester is completely hydrophobic
true!!!
What are the functions of cholesterol?
-can synthesize vitamin D from sunlight UVB rays
-found in cell membranes to stabilize it, adds rigidity and fluidity
-precursor for steroid hormones like progesterone, androgens estrogen, etc)
-precursor for bile salts
note: cholesterol can be removed when it gets converted to bile and then can be recycled or pooped out (we need to be able to do this bc the liver creates enough cholesterol and then getting it through diet causes build up)
What are the food sources for cholesterol?
any animal food/byproduct
Is cholesterol essential?
NO
What is the precursor for sex hormones, stress hormones, and vitamin D?
cholesterol
Which of the following is composed of glycerol plus 3 FA chains?
A) omega 3
B) steroids
C) omega 6
D) fat
D) fat
