Chap 9 and 10: lipids and membranes pt. 2 Flashcards
What are Terpenoids also called?
Isoprenoids
what are Terpeniods
they are lipids that are built from isoprene units rather than fatty acid
What is Isoprene composed of?
a basic 5 carbon unit
What makes up a terpene?
2 Isoprene
What are more complex Terpenoids built from?
built up from multiple isoprene units
*know the structure of Isoprene
okayy
What produces Terpenes?
produced primarily by a wide variety of plants and also some insects
Archaeal Cell Membranes are built from what?
from glycerophospholipids with isoprenoid tail and ether linkages
What vitamins are Isoprenoids?
A, D, E, K
Vitamin def
compound that are essential to the health of humans and other vertebrates that cannot be synthesized so they must be obtained in the diet
Steroid (cholesterol) Biosynthesis
-Squalene cyclization = steroid nucleus/backbone
-Squalene=triterpene–> so steroids are terpenoids
-enzyme-catalyzed addition of oxygen atom to squalene to form an epoxide followed by Enzyme catalyzed cyclization = steroid nucleus
Steroids make-up
-characterized by Steroid nucleus:
-made up of 4-fused rings, -three 6-membered rings, and -one 5-membered rings fused together
-rings are planar (wedged-shaped)
Where are steroids present in?
-present in most Eukaryotic Cells
Cholesterol is most common where and a precursor for what? and properties
-most common steroid in animals
-precursor for all other steroids in animals
-mostly nonpolar, mostly water insoluble
***know structure
Steroids function
-salt balance and metabolic function, and sexual function in animals
-part of endocrine signaling
endocrine signaling def
messengers secreted by glands and carried though the bloodstream to distant targeting tissues
Steroid properties
-lipid soluble
-receptors are cytoplasmic (hydrophobic)
-bacteria can not synthesize steroids
-are cholesterol derivatives
***recog steroid backbone
What is Vitamin D3 (cholecalciferol)?
steroid hormone (terpenoid) that regulates Ca 2+ metabolism
What are Bile Acids (BAs)/ Bile salts?
(what kind of detergent?)
(how to recognize?)
-they are an oxidation derivatives of cholesterol
-they are amphiphilic detergents
**look for polar head and steroid backbone
***recog/draw cholesterol esters
OKAYY
What does fat absorption require?
requires Bile salts
What does bile salts due for fat absorption (2 things)
-they aid in digestion (dissolve fats in small intestine , with micelles, to allow absorption into the blood)
-play a role as cofactors and pigments
What are Cholesterol Esters? what are they involved in?
-they are made from fatty acid esterified to cholesterol alcohol (OH)
-they are involved in cholesterol transport in lipoproteins
What are Lipoproteins?
they are protein + lipid (TAG and cholesterol) that work as lipid transport in the circulation
Structure of lipoprotein
-Monolayer of glycerophospholipid (amphipathic)
-inside/core of the monolayer there are nonpolar lipids (TAG and cholesterol esters)
-some cholesterol are found in the monolayer
-proteins (apoproteins) are found outside of the monolayer
**looks like a micelle
function of lipoprotein
-Oil drop: coated with proteins and glycerophospholipid skin
-allos TAGs and cholesterol to be transported to organs to use as fuel or deposit to storage molecules (adipose tissues)
Largest lipoproteins have what?
the lowest density
Chylomicrons function (lipoproetein)
-transport dietary TAGs + cholesterol from the intestine to liver
-transport TAGs–>muscle + adipose
Atherosclerosis def, function, and associated with what?
-low density Lipoprotein (LDL) = bad cholesterol
-transports cholesterol from the liver
-associated with the deposition of cholesterol on the arterial walls
High density Lipoproteins def and fucntion
-also known as HDL
-good cholesterol
-transports cholesterol to the liver
-associates with carrying cholesterol out of the blood
IDL
Intermediate density Lipoprotein
VLDL
Very low density lipoprotein
what causes Heart attacks?
-rupture of arterial plaque
-results in blood clots that causes blockage of artery in heart
-no RBCs and so no O2 supply past clot
-heart muscle death
-can result in physical death
Cholesterol Transport process diagram
VLDL–>IDL–>LDL; HDL
-Chylomicrons carry dietary lipids from the intestines and deliver TAGs to cells
-VLDLs carry lipids from the liver and deliver TAGs to cells
-IDLs are derived from VLDLs
-LDLs are derived from IDLs and are primary cholesterol delivery to cells
-HDLs carry cholesterol from cells for disposal back to liver
GO O OVER IN SLIDE 34
Cholesterol Transport: Chylomicrons
carry dietary lipids from the intestines and deliver TAGs to cells
Cholesterol Transport: VLDLs
carry lipids from the liver and deliver TAGs to cells
Cholesterol Transport: LDLs
are derived from IDLs and are primary cholesterol delivery to cells
Cholesterol Transport: HDLs
-HDLs carry cholesterol from cells for disposal back to liver
Cholesterol Transport: IDLs
-IDLs are derived from VLDLs
Phospholipases def
enzymes that hydrolyze the ester/phosphoester bonds of phospholipids
Phospholipases are named by what? and what contains phospholipases?
-named by which ester bond hydrolyzed
-venoms of poisonous snakes contain phospholipases (A2)
what does a lysophospholipid do?
acts as a detergent that dissolves RBC membranes causing them to rupture
Phospholipase rxn
looks at diagram S(36) creates lysophospholipid
What are Eicosanoids? (def)
derivatives of arachidonic acid released by enzymatic cleavage from membrane phospholipids
-2 or more step process
Eicosanoids are what kind of hormone?
-they are paracrine hormones (short signaling): hormones that have an affect on cells near where they have been synthesized
-also called local signaling
Eicosanoids hormone signaling/ PGH2 synthase
- Phospholipase A2 cuts at C2 carbon of a membrane phospholipid
- arachidonic acid gets released (C20)
- prostaglandin H2 synthase (PGH2 synthase, Cyclooxygenase, COX) + O2 reacts with arachidonic acid
- makes prostaglandin H2 (PGH2) a hormone
- this hormone can increase body temp., inflammation, pain, uterine smooth muscle contraction
NSAID def and types
-Nonsteroidal Anti-inflammatory Drugs
-Ibuprofen, Naproxen
What kind of competitors are NSAIDs
Reversible Competitive inhibitors of PGH2 Synthase= cyclooxygenase=COX
*suicide inhibitor or RSA
what do naproxen and Ibuprofen contain
contain benzene rings and carboxylic acids
Biological membrane is composed of what?
-continuous phase (lipids)
-discontinuous phase (lipids)
- a mosaic
-proteins
-lipid link proteins
*chart on S40
Biological membrane: continuous phase
fluid lipid bilayer matrix (2D sea)
Biological membrane: discontinuous phase
proteins floating in the lipids like rafts/icebergs
Biological membrane: mosaic
made up of different proteins that interact with the lipid bilayer by electrostatic interaction (extrinsic/ peripheral membrane proteins)
*bind via non-covalent interactions to membrane surfaces
*easy to solubilize and separate by pH, salt concentration, urea
Biological membrane: proteins
partially/completely penetrate or span the lipid bilayer (intrinsic/integral membrane proteins)
*req detergents to remove
Biological membrane: lipid linked proteins
can be released from membrane by phospholipase C
* can be in the cytosol and ECM side of the membrane
Peripheral membrane proteins (PHP) def
bind via non-covalent interactions to membrane surface
-can be on cytosol and ECM side
-easy to solubilize by pH, salt conc, urea
Integral membrane proteins (IMPs)
have hydrophobic region that associates with membrane; hard to remove and difficult to solubilize (spans the membrane or penetrates it)
*require detergents to remove
*contain alpha-helix and beta-barrel
mild nonionic detergent fucntion
dissolves membranes without unfolding proteins
*some can only be used to remove only peripheral proteins
(amphipathic)
Ionic detergent
dissolves membranes and unfolds/denatures proteins
*removes integral and peripheral proteins
Sucrose specific porin def
Porins act as pores thorugh which less molecules can diffuse
-prevalent in mitochondria, in outer membrane, and Gram negative bacteria
Lateral Diffusion
-can diffuse laterally (side ways)
-can rotate in the plane of the membrane
-CANNOT diffuse transversely through membrane
*very fast
Fluid-Mosaic Model
-in a liquid-crystal (fluid) state
Transverse diffusion
-proteins can flip to the opposite layer
-NO lateral diffusion
-can rotate
-proteins float around membrane like icebergs
*very slow
what technique showed proof of lateral diffusion?
FRAP- Fluorescence Recovery After Photobleaching
what does FRAP- Fluorescence Recovery After Photobleaching do?
laser bleaches and destroys fluorescence of a label in a region of membrane
-fluorescence recovers and diffuses into damaged region
Flippases def
facilitate the lipids flipping from one layer to another and can help a lipid flip back to original
(help transverse diffusion)
What kind of symmetry is a membrane bilayer?
It is Asymmetrical
-2 halves of the bilayer have different phospholipids and glycolipids
where are carbohydrates located on the bilayer?
carbs whether attached to protein or lipids are located on the non cytosolic side of the bilayer
-contribute to Transverse Asymmetry
Where are proteins located on the bilayer?
proteins are embedded in the membrane in a specific orientation crucial to their function
-contribute to Transverse Asymmetry
Lipid Rafts def and function
-def: Sphingolipids and sterols self associate into unique domains within the membrane
-particular membrane proteins may be recruited/ excluded from rafts
-fuct: participate in recognition, signaling
Sphingolipid saturated chains like to self associate due to what?
Van der Waals (hydrophobic) interactions
