Lipids Flashcards
Give 2 function of terpenes
Disease resistance, signalling
Why do most fatty acids have an even number of carbons?
Due to the mode of synthesis - putting together couples of carbons
There are rarely more than _double bonds in an unsaturated fat
4
Unsaturated fats usually have their double bonds on carbons _
9, 12, 15
Simple triacylglycerols have __ fatty acids
3 of the same units of
Which type of cells specialise in fat storage?
Adipocytes
White fat cells store _
A single droplet of fat and oil
Brown fat cells store _
Multiple membrane bound droplets of fat/oils
Which type of fat cell increases in number as a person gains weight?
White adipocytes
How do plants use triacylglycerols?
They are stored in seeds for use as an energy source after germination
Triacontanol is _
an example of an alcohol which reacts with fatty acids
The esterification between triacontanol and palmitic acid produces _
Beeswax
Compare melting point of waxes to triacylglycerol
Waxes have higher melting points
Alcohols that react with fatty acids tend to have _
Long R groups
How do you form a soap?
By heating triacyclglycerols with an alkali, like sodium hydroxide
What happens during saponification?
Ester linkages are broken between fatty acids and glycerol,
Fatty acids form salt with the cations of an alkali
What are micelles?
Aggregates of salt molecules, which form a spherical structure with hydrophilic carboxyl groups on the surface, and hydrocarbon chains embedded within
Glycerophospholipid structure:
Like a triacylglycerol, but one fatty avid is replaced with a hydrophilic group known as the ‘head’
What kind of bond links the ‘head’ to the rest of the molecule in glycerophospholipids?
Phosphodiester bond
A cerebroside is_
A sphingolipid with a simple sugar head group
A ganglioside is _
A sphingolipid with a complex sugar head group
The components of a sphingolipid are _
Sphingosine, with a hydrophilic group ‘head’ and a fatty acid chain on second carbon
What is the most diverse type of natural product?
Terpenes
What 2 factors give terpenes diversity
Varying lengths of chains, vast range of structural derivatives
Hemiterpenes have
one isoprene unit
Monoterpenes have
two isoprene units
the secreted resins of birch and spruce are largely composed of
diterpenes, with four isoprene units
Rubber is a _terpene with _ units
Poly
tens of thousands of isoprene
What process forms cross links between individual chains of rubber molecules. What does effect does it have on properties?
Vulcanization
Confers mechanical stability
Improves elasticity
What compounds are formed from the cyclization of squalene (a triterpene composed of 6 isoprene units)?
Sterols
The core structure of sterols is _
Four fused carbon rings, three with 6 carbons, and one with 5 carbons
What is the plant equivalent of cholesterol?
Stigmasterol
Bile acids like cholic acid, are sterols with _
Hydrophilic R groups
Derivatives of cholic acid are synthesized in the liver and then secreted in to the small intestine where they _
Emulsify fats, aiding digestion
Steroids are derivatives of
Sterols
What is the difference between the core structure of steroid and sterols
Steroids may have a variety of functional groups at a site at which sterols only have a hydroxyl group
What compounds are derived from arachidonic acid?
Eicosanoids
give 2 procceses which eicosanoids are involved in
reproduction, pain response
Paracetamol and aspirin function by
prevent formation of specific eicosanoids
Why are eicosanoids not true hormones?
Because they stay within the tissues in which they are secreted
Prostaglandins and thromboxanes are examples of _
Eicosanoids
Which vitamin is esssential for the syntheiss of photoreceptors in the eye?
Vitamin A
Which lipid vitamin is needed for correct functioning of blood clotting response?
Vitamin K
Which lipid vitamin is involved in prevention of oxidative damage in cells
Vitamin E
What determines the structre that an amphiphilic compounds will take in aqueous solution
The number of hydrophobic tails
What 3 types of lipids are in biological membranes?
Glycerophospholipids, sphingolipids and sterols
What property of membranes allows them to take different shapes?
Flexibility, can stretch 2-4% without breaking
What are the restrictions on movement for a lipid within a memmbrane?
It cannot easily move across to the other side. It can readily move along its layer - fluid mosaic
Lipids with longer hydrophobic tails form _ associations, and _ fluid membranes
closer
less
Lipids with kinks from _ associations and _ fluid membranes
looser
more
Membranes are more protein by _
Weight
Membranes are more fat by _
Number of molecules
Which membrane proteins can only be removed by disruption?
Integral membrane prot
Which membrane proteins can be removed wtihout disruption?
Peripheral membrane proteins
How are integral membrane proteins removed experimentally?
Using detergent, which resembles and functions like soap, using micelles
Give two types of transmembrane protein structures
Barrel-like structures made of beta sheets
Alpha-helical shapes spanning the membrane`
The internal face of transmembrane proteins often forms attachments with
Peripheral membrane proteins
What are lipid-linked proteins?
Peripheral membrane proteins which are linked to membrane lipids
What are lipid rafts?
Stable domains within which proteins can co-locate and function together
What can be said about fluidity of areas which function as lipid-rafts?
They are usually less fluid due to tighter associations between hydrophobic tails
Why are sterols common in lipid rafts?
They fit neatly between two glycerophospholipids
Compounds that can’t cross the membrane still influence events within the cell through _
Signal transduction
Give an example of signal transduction
Growth factors binding to proteins, inducing cell division
Carbohydrates on surface of membrane are held in place by _
attachment to lipids and proteins
Carbohydrate coating of cell membranes plays a role in
cell-cell recognition and provides protection
What molecules are able to cross membranes freely?
Water, gases like oxygen, nitrogen and carbon dioxide
Urea, ethanol (small molecules)
How does the GLUT1 transporter function?
Glucose binds to extracellular surface, causing a conformational change which allows glucose to flow down its gradient within the channel of the protein
What are the two sources of energy for transport
Hydrolysis of ATP
Coupling to the movmement of a molecule down its gradient
Give an example of a symporter
Na+ glucose transporter
what does the mammalian Na+ glucose transporter do?
It couples the diffusion of sodium ions in to intestinal cells from gut cells with the intake of glucose
Give an example of an antiporter
Na+/Ca2+ exhange protein
What does the sodium/calcium exchange protein do?
Uses the enerrgy from the diffusion of 3 sodium ions to power the export of a single calcium ion
Give the two types of ATP dependent pumps
ABC (ATP-binding cassette)
P-type
How do p-type transporters function?
The released phosphate group form ATP forms a transient attachment with the transport protein
Na/K ATPase moves _ pottasium ions _ and __ sodium ions _ for 1ATP
2 in
3 out
