Lipids and membranes Flashcards
What bonds does rotation occur in fatty acids?
SIngle bonds
What bond does not allow for rotation?
Double bond
What are examples of saturated steroisomerism?
Stearic acid
What are examples of unsaturated steroisomerism
Elaidic acid (trans isomer)
Oleic acid (Cis isomer)
How are trans-fatty acids caused?
Side reaction with the catalyst of the hydrogenation process
What are ingested fatty acids stored as?
Triglycerides
What is Olestra?
Sucrose esterified with long chain fatty acids
Why does Olestra cause cramps, gas and loose bowels?
Unable to be absorbed or metabolised
What is Saponification?
Hydrolysis of esters to form glycerol and soap
What is Sodium palmate?
A sodium salt of fatty acids derived from palm oil
What is Sodium oleate?
Soidum salt of fatty acids derived from olive oil
What is the structure of Micelle?
- Hydrophillic head groups on outside
- Hydrophobic hydrocarbon chain on inside
What is the structure of a bilayer membrane?
- Too long for micelle formation
- Head groups on outside
- Hydrocarbon chains on the inside
What is the liposome structure?
- Aqueous environment inside and outside liposome
What is Cholesterol a precursor to?
Steroid horomones in regulating gene expression
What is Cholesterol in bile acids used for?
- Dissoicate to produce bile salts
- Biles is used to solubilse, digest and absorb fats
What are the three phospholipids with different heads?
- Sphingolipids
- Phosphatidylcholine
- Phosphatidylethanolamine
What is a component of mitochondrial membrane?
Cadiolipin
What is preripheral proteins in membrane composition
Surface proteins with polar hydrophillic side chains
- Bind via covalent, non-covalent, ionic or hydrogen bonding interactions
What is integral proteins in membrane composition?
- Extend through membrane, contain non polar hydrophobic sequence
- Transport proteins
What is type 1 and 2 in integral proteins?
- Single transmembrane helix
- Amino terminus is on the outside
for type 1 and the inside for type 2
What is type 3 integral proteins in membrane?
- Mulitple transmembrane helices
- Single polypeptide
What is type 4 in intergral proteins?
- Transmembrane helices
of different peptides
form a channel
What is type 5 and 6 in integral protein?
- Peptide secured by lipid anchor
- Type 5 secured only by anchor, type
6 also has a transmembrane helix
What is Glycophorin?
Intergral prtoein found int he membrane of red blood cells
Where can the positive charged amino acids side chains in glycophorin be found?
In the cytoplamsic region
What are β barrels
- β barrel conformation stabilised by intrachain hydrogen bonding.
- β barrel only need 7-9 residues to span a membrane.
- Harder to detect β barrels from amino residue sequence alone.
How is fluidity in fluid mosaic model affected?
- Temperature
- Fatty acid saturation
- Sterols
What affect does temperature have on fluid mosaic model?
Temperature increase causes more disorder - more fluidity
What affect does temperature have on fluid mosaic model?
Temperature increase causes more disorder - more fluidity
What affect does fatty acid saturation have on fluid mosaic model
- Saturated fatty acids created rigid and ordered structure
- Unsaturuated are kinked so it causes fluidity
What affect does sterols have on fluid mosaic model?
- Pack unsaturated fatty acids into extended conformation causing less fluidity
- Associate with saturated fatty acids causing more fluidity
What do Sphingolipids and Cholesterol form in lipid distribution?
Microdomains
What does Microdomains cause?
Less fluidity due to being thick and ordered
What do Microdomains (rafts) do?
Rafts keep lipid molecules aggregated together and also
certain proteins and transporters close together.
What is Lateral diffusion?
Phospholipid moves throught he membrane, remaining on the same side of the bilayer
What happens in catalysed transbilayer diffusion?
Phospholipid moves from extracellular site to cytosolic site
What enzymes require energy
Flippase and floppase
What enzyme does not require energy
Scramblase
How is a cell marked for cell death?
Moving phosphatidylserine (a phospholipid) to the extracellular site marks a cell for cell death.
- Must be found in high numbers on the extracellular site.
What type of molecule can easily diffuse
through the plasma membrane?
• Small, non-polar molecules
• Water molecules (due to their small size)
What are the 3 transport methods?
Passive diffusion, facilitated diffusion, Active transport
What else are transporter proteins are known as?
Permeases
What is Erythrocyte glucose transporter (GLUT1)
Uniporter protein - passive facilitated diffusion
What is secondary active transprot?
X moves down concentration gradient
and provides the energy for S to move
against concentration gradient
What is Na+–K+ ATPase pump?
Pump helps keep the Na+
and K+ ions at different concentrations inside and outside the cell.
- Maintains the membrane potential
