module 2 - 5.1 structure and function of membranes Flashcards
what does the structure of plasma membranes allow?
allows cells to communicate with each other
what are the 2 types of membranes?
- cell membranes
- cell surface membranes/ plasma membranes
what holds a cell together?
cytoskeleton
which atom is on the end of a fatty acid tail?
oxygen
what is compartmentalisation?
formation of separate membrane-bound areas in a cell
what does compartmentalisation allow for the cell?
- allows different environmental conditions in different parts of the cell
- allows chemical conc. gradient to be made
- allows protection of cellular components
what does a proton pump do inside a membrane?
makes it acidic
what are membranes?
flexible fluid able to break and fuse easily
what are the roles of the cell surface membrane?
- environment
- transport
- cell to cell signalling
- cell to cell joining
- detection of changes in environment
- site of chemical reactions
what does the environment provide for the cell?
provides fixed conditions inside cell cytosol (cytoplasm)
what does transport do for the cell?
provides partially permeable membrane that creates a barrier to some substances, controlling transport of substances in and out of cell
what does cell to cell signalling do for the cell?
has proteins (glycoproteins or lipiproteins) on it which interact with other cells
what is signal transduction?
process of cells responding to substances outside the cell
what does signal transduction do?
detects changes in environment
what do enzymes act as in the membrane?
- site of chemical reactions for the cell
- some proteins in the membrane may be enzymes
what does cell to cell joining allow the cell to do?
tissue formation
is the head of the phospholipid hydrophilic of hydrophobic?
hydrophilic
what is the hydrophilic head made up of?
- phosphate group
- phosphoester bond
- glycerol
is the tail of the phospholipid hydrophilic of hydrophobic?
hydrophobic
what is the hydrophobic tail made up of?
- ester bond
- fatty acid
how are the fatty acid tails positioned?
towards each other they do not overlap e.g.
o==o
o==o
o==o
what is the structure of a phospholipid?
- has a polar head (made of a glycerol and phosphate molecule)
- has 2 fatty acid non-polar tails
- they are amphipathic
what is the arrangement of a phospholipid?
- spontaneously arranged into a bilayer
- hydrophobic tails face inwards, surrounding polar fluids
- 2 hydrophilic heads face outwards, touching extracellular fluids
when do phospholipids form micelles?
when submerged in water
why is a phospholipid amphipathic?
because phospholipids have hydrophilic and lipophilic regions
what does trilaminar mean?
it has 3 layers