Topic 3: Membranes Flashcards
Describe fatty acids
Long chain of carbon atoms with a carboxyl group at one end
Average number of carbons in a fatty acid chain
12-20
Describe triacylclylcerols
3 fatty acids bound to a glycerol anchor
Describe a phospholipid
a glycerol head at the top, attached to two fatty acid tails
What are triacylglycerols used for?
to store energy
‘Amphipathic’ means…
having both hydrophilic (polar) and hydrophobic (non-polar) properties
A micelle is…
a formation of phospholipids, like an oil drop in water. Glycerols face outwards.
A liposome is…
a formation of phospholipids, used in medicine to deliver needed substances. Hollow ball of phospholipids, with hydrophilic properties facing outwards, but also inwards in a second layer
Which type of proteins go all the way through the membrane?
Integral Proteins
Peripheral proteins never touch….
the hydrophobic core
Amphipathic proteins are…
integral proteins
Four functions of membrane proteins
Transport, enzymatic activity, signal transduction, and attachment recognition
Sterols can prevent freezing in the bilayer by…
embedding themselves between the phospholipids, preventing them from packing too tightly
Sterols can prevent melting in the bilayer by…
embedding themselves between the phospholipids to fill in the gaps.
Four ways to increase membrane fluidity
1) short chain fatty acids
2) unsaturated fatty acids
3) sterols
4) higher temperatures
Four ways to decrease membrane fluidity
1) long chain fatty acids
2) saturated fatty acids
3) sterols
4) lower temperatures
True or False: Sterols are amphipathic
True
Order the following from best to worst for crossing the cell membrane:
Ions, small uncharged polar molecules, large uncharged polar molecules, non-polar molecules
1) non-polar molecules
2) small, uncharged polar molecules
3) large uncharged polar molecules
4) ions
True or False: facilitated diffusion is active transport
False
Aquaporins are…
narrow channel proteins that allow the passage of water across the membrane
A Gated channel is…
a channel protein that can switch between open, closed, and intermediate states to transport most ions across the cell membrane
Carrier proteins…
passively transport larger molecules across the cell membrane using diffusion and facilitated transport
Why do cells need a selective barrier?
To maintain homeostasis in dynamic environments
How does diffusion work in relation to the concentration gradient of a solute
works with the concentration gradient to reach equilibrium, does not require ATP