Lecture 9 Information Flashcards
What are lipids used for?
Energy storage
Cell structure (like bilayer)
Signaling molecules, cofactors, and pigments
What is an advantage of lipids as a fuel versus sugars energetically?
Lipids are hydrocarbons so they have less oxygen
Since oxygen oxidizes carbon and takes away electron density, it lowers the energy of the molecule
Therefore, lipids have more energy than sugars since they have less oxygen
What is an additional advantage of lipids a fuel versus sugars?
they are insoluble in water so there is no extra water weight
in other words, fat is lighter
What is the structure of fatty acids?
Carboxylic acid with a hydrocarbon chain
Saturated fat
no double bonds
Unsaturated fat
has double bonds
What is healthier saturated or unsaturated fat?
Unsaturated fats like olive oil
What happens as chains get longer in fatty acids?
Solubility decreases
longer chains interact with each other through Van Der Waals interactions and can precipitate out of solution
What are typical lengths for fatty acids?
Even numbered length between 12 and 24 carbons
What conformation are double bonds in in fatty acids?
cis
What happens to fluidity when a molecule is saturated?
becomes less fluid because strands can get closer together due to lack of kinks
What creates trans-fats?
hydrogenation to increase storage life and make more stable at high temperatures
Triaclygylcerols
3 fatty acids and a glycerol linked together through ester linkages
Where do we find Triaclyglycerols?
In adipose cells for energy storage
Characteristics of Triaclyglycerols
very insoluble
can be simple or mixed
Lipases
enzymes that hydrolyze off fatty acids for export of energy
What happens if lipases do not work?
Get a build up of the lipid that precedes the enzyme in the pathway
Can lead to cell death and neurogenerative diseases
Examples of neurogenerative diseases caused by malfunctioning lipases
Tay Sachs
Niemann-Pick
What causes Niemann-Pick disease?
sphingomyelinase which breaks down sphingomyelin doesn’t work
Wax
two long hydrocarbon chains linked together through an ester carbonyl group
Characteristics of wax
high melting point
water repellent
allows for bouyancy in whales since wax is lightweight
Phospholipids structure and characteristics
amphipathic molecules
two fatty acid chains with a phosphoryl group head
form bilayers
What type of molecules have trouble crossing the phospholipid bilayer?
hydrophillic/polar molecules
the lipids are hydrophobic and make it hard for polar molecules to cross
Liposome
spherical-shaped vesicle that is composed of one or more phospholipid bilayers
thought to be the early structure of cells in evolution as water and RNA mixed in the sphere
List 5 general membrane lipids
Glycerophospholipids (aka phospholipids) Spingolipids (can be a phospholipid too) Sterols Galactolipids/sulfolipids Tetraether lipids (not ours, these are archaeal)
Glycerophospholipids
two fatty acids that are attached to glycerol
have a phosphate group attached to the glycerol
Do all Glycerophospholipids have two fatty acid chains?
No
Some molecules found in the heart only have 1 fatty acid chain
This makes it harder for lipases to cut the phospholipid
Examples of Glycerophospholipids with one fatty acid chain
Plasmalogen and platelet activating-factor
Spingolipids
do not use glycerol, but instead have one hydrocarbon chain known as the sphingosine
List three types of Spingolipids, which are determined by the group attached to the sphingosine
Sphingomyelin
Glycosphingolipid
Gangliosides
Sphingomyelin
a type of spingolipid that has a phosphate group attached to the sphingosine
is technically a phospholipid
only one fatty acid chain per phosphate
has no net charge on head
Glycosphingolipid
a type of spingolipid that has a sugar group attached to the sphingosine
usually on outer face of plasma membrane with sugar group
no net charge
sugar group helps contribute to recognition
Gangliosides
a type of spingolipid that has multiple sugar groups attached
net negative charge from sialic acid
What is attached to sugars on gangliosides?
sialic acid
can have one or multiple sialic acids attached
Sterols
structural lipids found in the membranes of most eukaryotes
made from the steriod nucleus
Are cholesterols polar?
they are amphipathetic with polar -OH group on the steriod nucleus head
Describe the steriod nucleus
planar and stiff
made from ring structures
Do steriods always have a hydrocarbon tail?
not always! defining feature is actually the steriod head
Taurocholic acid (bile acid)
an example of a sterol
emulsifies fats by tearing apart glycerol
makes fats more likely to be broken down by lipases
Borrelia burgdorferi
bacteria that causes lyme disease
45% of its lipids are cholesterol-glycolipids, but the bacteria itself cannot make cholesterol
Borrelia burgdorferi gets cholesterol from the host that they have infected
Examples of signaling lipids
Phosphatidylinositol and sphingosine derivatives
Eicosanoids
Steroid hormones
Vitamins A, D, K and E
Phosphatidylinositol 4,5 Biphosphate (PIP2)
a signaling glycerophsopholipid
has a total of 3 phosphates in its glycerol head structure
PIP2 mechanism
is processed by phosholipase C which removes the triglycerol head (IP3)
IP3 goes into the endoplasmic reticulum to signal the release of calcium
Diacyl glycerol (DAG) remains in the cell membrane and can also serve as a signal
DAG interacts with protein kinase A which binds calcium and results in the phosphorylation of many molecules
What type of signaling are Eicosanoids involved in?
paracrine signaling
short distance signaling
What are all types of Eicosanoids derived from?
Arachidonic acid
Prostaglandin
a type of eicosanoid that is characterized by a 5 membered ring
Prostaglandin is involved in fever, muscle contracting, blood clotting
NSAIDs
nonsteriodal anti-inflammatory drug
inhibits COX which synthesizes prostaglandin
this reduced prostaglandin and the effects of inflammation
Steriods
used in endocrine (long distance) signaling
have ring structure
How do steroids signals interact with the cell?
they are hydrophobic so they can cross the lipid bilayer and go into the cell
receptor for steroids is often inside the cytoplasm
receptors binds the steroid hormone than go into the nucleus where they act as a transcription factor for gene expression
Two uses for Vitamin A
is used in retinol form in our eyes
regulates gene expression for tissue growth as retionic acid
Are vitamins soluble?
No
Vitamin A and your eyes
B-carotene is cleaved to make two vitamin A molecules which are oxidized to make retinal pigment
when light hits retinal pigment, there is a configurational change from cis to trans which triggers signal to brain
(Retinal pigment can also get transformed into retinoic acid which is used to signal epithelial cells)
Vitamin D
when UV light hits the skin, we produce vitamin D3
Vitamin D3 gets converted by our kidneys and livers into usable nutrients
People with melanin block UV light which can lead to vitamin D defencies
Vitamin E
Isoprenoid obtained from our diet
Antioxidant- associated with cell membranes and lipoproteins
Protects unsaturated fatty acids from accidental oxidation
Vitamin K
Isoprenoid obtained from our diet
Undergoes cycle of oxidation and reduction during formation of Prothrombin
Important for blood clotting
Isoprenoid
Specific type of carbon group found in vitamin E and K
Other isoprenoids are Warfarin, Ubiquinone, and Plastoquinone
What are most lipids polymers of?
isoprene
What is prostaglandin made from?
fatty acids
What does platelet activating factor contains?
an ether-linked alkyl group
What is cardiolipin?
a glycerophospholipid
NOT a sphingosine
Name some sphingolipids
ceramide
cerebrosides
gangliosides
What do cerebrosides contain?
fatty acids
Are sterols commonly found in bacteria membranes?
no
Tay-Sachs disease is caused due to
genetic defect in the metabolism of gangliosides
Which vitamin is not fat soluble?
vitamin C
What is vitamin D derived from?
cholesterol
What is cortisol derived from?
sterols
Why do lipids float?
lower specific gravities than water
What do archael membrane lipids have?
alkyl acids
An example of a glycerophospholipid that is involved in cell signaling is:
phosphatidylinositol
What are biological uses of waxes?
energy storage
lubrication
water proofing
structure
Are triaglycerols found in membranes?
no?
Why is platelet activating factor so water soluble?
it’s ester linked acetic acid at the C-2 of glycerol
What type of membrane lipids are commonly found in plants?
galactolipids
Fatty acids are attached to sphingosine by what type of chemical linkage?
amide
Bile acids are derived from what?
cholesterol
Signaling lipids produced by platelets in formation of blood clots
thromboxanes
Nonsteroidal antiinflammatory drugs (NSAIDs) inhibit the synthesis of which signaling lipids from arachidonic acid?
both prostaglandins and thromboxanes
Thromboxanes
help with blood clotting
a type of cholesterol
Is aspirin lipid based?
no
Glycerophospholipids
membrane lipids
two fatty acids are attached through ester linkage to glycerol
glycerol also has a phosphodiester linkage and phosphate
glycolipids
a sphingolipid that has a simple sugar or complex oligosaccharide at their polar ends
ether lipids
plasmalogens and platet-activating factors
are linked to glycerol-phosphate through ethers
found in the heart
galactolipids
predominate in plant cells
a type of membrane lipid
one or galactose residues are connected by a glycosidic linkage
sphingolipids are what type of lipid?
membrane lipid
ceramide
the parent of all sphingolipids
a fatty acid attached to the amide of the sphingosine
Cerebrosides
have a single sugar linked to cermide
Globosides
glycosphingolipids with two or more sugars
What determines blood type?
sphingolipids in the membrane
In what organelle are phospholipids and sphingolipids degraded?
lysosomes
What are the 3 types of eicosaniod signaling lipids?
prostaglandins
thromboxanes
leukotrienes
steriod
oxidized derivatives of sterols that are used in endocrine signaling
Difference between steriods and sterols?
Steriods are a type of sterol used for signaling
Not all sterols are used in signaling. For example, cholesterol is used in the cell membrane for fluidity
Prothrombin
proteolytic enzyme that splits peptide bonds in the blood to convert fibrinogen to fibrin
Do branched chains increase or decrease fluidity?
increase fluidity
