Membrane Fluidity And Membrane Protiens Flashcards
What is the maximum number of double bonds in a fatty acid
6
Why are cis double bonds better than trans in fatty acid tails?
Cis bonds are more reactive, and allow more reaction in the cell for metabolism and cell signalling
They give more bend which increases fluidity of the tails
What determines the physical state of the membrane and what is it influenced by
Fluidity/ viscosity
Influenced by temp
What is transition temperature
The melting temp
When it turns from solid to liquid
If you’re below transition temp what happens to the membrane
If above
More rigid and tightly packed
More fluid and movement
What is transition temperature (fluidity) affected by?
Fatty acid chain saturation
Cholesterol content
Fatty acid chain length
Interactions in membrane phospholipids are held together by
Van der waals
If you have less van der waals interactions what does this mean
Tails further apart, more fluid
What does fatty acid chain saturation do to fluidity
If saturated, the fatty acids are less fluid, and straight flexible rods
In cis unsaturated, the fatty acids bend at the double bond so they’re more fluid
What does cholesterol content do to fluidity
Cholesterol has rigid hydrophobic rings that impair the movement of the fatty acid tails at lower temp
DONT JNDERSTAND
What does fatty acid chain length do to membrane fluidity
Shorter chains less van der wall interaction, so more fluid because less energy needed to break them apart
If longer more interactions, more rigid
Why is a balance of membrane fluidity and rigidity important
It helps keep structural organization and support
Is enables interactions (clusters of protiens
Is helps with membrane assembly, cell growth, cell division
Helps in cell movement, secretion, and endocytosis
What do cells do to respond to changing environmental conditions?
That alter third lipid compositions to maintain membrane fluidity
How do cells respond to cold temps to maintain membrane fluidity
What is hot temp?
Temp is cold so they want to become more fluid
They desaturate single bonds in the fatty acid chains (make double bonds)
They reshuffle their chains between other phospholipids to make two unsaturated fatty acids
They change the type of phospholipids they synthesize, so they make more fatty acids with unsaturated (double) bonds and shorten fatty acid chain lengths
If hot they do the opposites
What enzyme desaturates single bonds
Desaturase
What happens to the transition temp if saturated fatty acids are increased
More saturated (more single bonds) more rigid.
Transitions temp increase cause it take more energy to go from rigid to fluid
Is you have more double bonds what happens to transition temp
More fluid so lower transition temp
More likely to be fluid (melt) at lower temp
How are protiens distributed across the two leaflets of the membrane bilayer
Asymmetrically
What are the three classes of membrane protiens
Intergral Protiens
Peripheral proteins
Lipid anchored proteins
What are integral membrane protiens
They are protein that are permanently anchored to or are part of the membrane
Include mono topic, bitopic and poly topic proteins
What are mono topic, bitopic and poly topic proteins
mono topic: spans only one of the membrane leaflets
Bitopic: spans the whole leaflet
poly topic: spans the whole leaflet multiple times
What are transmembrane protiens
Proteins that pass through the lipid bilayer and have one or more transmembrane domains
Act as receptors channels or have roles in electron transport
Amphipathic
What integral membrane protiens are also Transmembrane protiens
Bitopic
And
Polytopic
Transmembrane domain of transmembrane protiens are generally
The surface of the transmembrane proteins are
Channels in the membrane may also be
Hydrophobic (do vanderwal with fatty acids in the bilayer)
Hydrophilic
Hydrophilic
Stuff about glycoprotein A slide 15
Idk
What is a way to identify the transmembrane domains
By doing computational analysis of amino acid sequence in the membrane to find the transmembrane domains
It’s usually a string of 20 nonpolar amino acids to span both top and bottom layer of the membrane
Lost the major membrane functions
Compartmentalization
Scaffold for biochemical activities (enzymes there to make sure inter actions occur)
Selectively permeable barrier
Solute transport
Response to external stimuli
Cell-cell communication
Energy transduction (mitochondria turns carbohydrate energy to atp)
