Exam 2: Macromolecules: Lipids Flashcards
Functions of lipids (6)
- energy
- storage
- structure
- insulation/protection
- hormones
- cell signaling
Structure of lipids (2)
fatty acids and sterols
fatty acids
long chain of hydrocarbons (hydrophobic) with a terminal carboxyl group
sterols
aromatic structures, derivatives of cholesterol
2 types of fatty acids
saturated and unsaturated
saturated fatty acids
all C-C single bonds
- saturated with hydrogens
- solid at room T
unsaturated fatty acids
contain one or more C=C double bond
- more fluid because kinked, it is harder to push them together
Do animals or plants have more saturated fats?
animals
In unsaturated fatty acids which form is more common, cis or trans?
cis
cis
2 hydrogens on the same side of the bond, get bend due to steric hindrance
Which is less common in nature, cis or trans, and why?
trans
- it is easier to remove hydrogens
trans fats
- remove hydrogens to get double bonds
- most dietary trans fats are man made
Fatty acid nomenclature, what does it mean if 18:0
there are 18 carbons
there are 0 double bonds
Which type of fatty acids have an expanded nomenclature?
unsaturated fatty acids
Fatty acid nomenclature oleic acid: 18:1 delta9
18 carbons
1 double bond at position 9
where do you start counting for fatty acid nomenclature?
carboxyl group
what is a carboxyl group
COOH
Polunsaturated
many double bonds
arachidonic acid : nomenclature: 20:4 delta 5,8,11,14
20 C
4 double bonds at position 5,8,11,14
essential fats and an example
can not make them and need to get them from our diet
arachidonic acid
How does classifying by omega groups work?
it bases them on the location of the double bonds in relation to the terminal methyl group
What are omega 3 fatty acids used for?
- development, to make membranes, neurological, immune response
- helps regulate inflammation
Where can you get Omega 3s in your diet?
nuts and fish
- can get mercury from eating fish
What is and where are omega 6 fatty acids found?
it is in meat like chicken, soy, nuts
helps in clotting, platelet aggregation
What does the American diet give you in relation to omega 6 fatty acids and omega 3 fatty acids?
a 15:1 ratio, more omega 6 fatty acids
- this promotes inflammation and risk for clotting
Fatty acid modifications: Eicosanoids
group of hormones and signaling molecules produced by oxidation of fatty acids
What are the primary enzyme involved in eicosanoid synthesis?
cyclooxygenases (COX) and lipoxygenases (LOX)
What do COX produce?
prostaglandins and thromboxanes (prostanoids)
What do LOX produce?
leukotrienes and lipoxins
Eicosanoid modification purpose
to change basic fatty acids to have a localized signal
- immediate tissues/cells
- inflammation/blood blotting right where it occurred
leukotrienes
stimulate immune response
- pro-inflammatory activity
lipotoxins
resolve inflammation
COX
increases inflammation
LOX
decreases/resolves inflammation
The COX pathway results in molecules with what type of structure?
cyclic structure
Prostanoids
locally active hormones/signals that are rapidly degraded
- exhibit opposing functions that are kept in balance
ex: some repel platelets off of the surface but then others are ready to send a signal to stick fast in the case of damage
Prostanoid (a COX) functions:
- inflammation mediation
- cardiovascular homeostasis
- reproductive function
Do fatty acid monomers directly connect with eachother?
NO
How are fatty acids connected?
need a linker molecule like glycerol, synthesis through dehydration rxn
- can get mono, di, and triglycerides
functions of glycerides/acylglycerols (2)
- energy storage
- insulation/protection
store in adipose tissue to have for protection
What do phospholipids start out as?
diacylglycerol with a phosphate group covalently bonded to the third site of the glycerol molecule
The presence of a phosphate changes the diacylglycerol to….
phosphatidic acid
functions of phospholipids (3)
- membrane structure
- signaling
- fatty acid reservoir for hormone production
phosphatidic acid structure
hydrophilic head, hydrophobic tails
what does the composition of fatty acid chains determine about the membrane
the fluidity/rigidity
increasing unsaturated fatty acids…..
increases fluidity
Fluidity of the membrane and reactivity
more fluid = more reactive
more rigid = less reactive
Modifications of phospholipids
phosphatidyl choline
phosphatidylinositol
Phosphatidylcholine
- component of HDLs
- increases fluidity
- yields fatty acids for signaling
Phosphaidylinositol
- high concentration in nerve cells
- cell attachment/organization
- signaling
Uncontrolled diabetic and phosphatidylinositol
not enough of this
get numbness, pins and needles
What are sterols
cholesterol and its derivatives
Functions of sterols (4)
- structural component of membranes
- hormones (progesterone, testosterone)
- bile salts
- vitamins
Sterol Nomenclature
ol ending due to presence of alcohol group
one or oid ending for derivatives
Cholesterol and membranes
- embeds in the hydrophobic region of the membrane
- stabilizes the transition state of membrane
What happens if you increase cholesterol past the stabilizing transition state?
- stabilizes solidity, make membranes with less fluid, when get imbalanced it shuts them down
Organ transplants and steroids
given lots of steroids to have it imbed in membranes of the immune system to shut down the immune response
All steroid hormone production begins with cholesterol entering the ______ and undergoing conversion to _______
mitochondria
pregnenolone
What can pregnenolone be converted to?
mineralcorticoids (Na, K), glucocorticoids, estrogens and androgens
insulin
brings blood sugar down
glucocorticoids
bring blood sugar up
ex: cortisol
Steroidogenic Pathway
production of steroids
everyone makes estrogen and testosterone
If injured what may you go on to recover?
anabolic steroids
some gave pregnenolone which increases cortisol and androgens, but this is giving them the precursor for anabolic steroids
Steroid hormone action
do not bind on membrane, diffuse into cell (it enters cell first to see if a receptor exists)
the hormone receptor complex goes into the nucleus and is a transcription factor (promotes transcription of certain proteins needed)
effects DNA transcription and how much product is put out
Long term effects of steroid use in athletes
unusual cancers
compromised immune system
If no receptor what happens to the anabolic steroid?
it sticks in the membrane and if there is too much it cannot be broken down
cell reactivity decreases
What happens when there is a receptor for the steroid?
the complex becomes a transcription factor
What happens when no receptor for steroid?
it can be broken down
If excess steroid….
it can be stored in membrane , too much inc rigidity and dec cell reactivity
(how steroids are used to shut down immune system)
The liver produces _____ to aid in the _____ in the small intestine
bile salts
emulsification of fat
- make larger fat into smaller pieces to increase SA
what do bile acids interact with to form bile salts?
sodium
Which fat soluble vitamins are based on cholesterol?
A,D,E,K
- essential vitamins, need to come from diet
What vitamin can we make on our own?
vitamin D
