1.3 Flashcards
define hydrophobic
- molecules that repels water
- it only bonds with other hydrophobic molecules
- e.g. lipids aka fats
define hydrophilic
- molecules that are attracted to water
- only bonds with water or other hydrophilic molecules
- e.g. proteins
define amphipathic
- partly hydrophobic partly hydrophilic
- allowing them to bond with water, hydrophobic or hydrophilic molecules at the same time
list an example of an amphipathic molecule and give reasons to why that is
phospholipids, which is a central component of he plasma membrane
- its part phosphate part lipid
- phosphate head - due to its -ve charge its hydrophillic
- lipids tail - due to their neutral charge its hydrophobic
describe how the phospholipid bilayer is suited to its function (6)
- phospholipids have hydrophilic heads and hydrophobic tails
- hydrophilic heads attracts to water
- hydrophobic tails repel water
- heads orientate outwards and tails inwards
- attraction of heads to wtaer and tails to fluid creates stability
- cholesterol reduces membrane fluidity
- fluid membrane is pinched during endocytosis or exocytosis
- integral and peripheral proteins enable transport across the membrane
describe the structure, positioning and function of cholesterol (3)
- cholesterol is amphipathic
- cholesterol is a steroid
- cholesterol is found between adjacent phospholipids
- it reduces membrane fluidity
- it reduces permeability to hydrophilic particles
what does cholesterols do to the phospholipid flow?
- it has an affect on the phospholipid flow
- makes the membrane stiffer and reduces its permeability
where are proteins found on the bilayer and what are they called?
- found on the outside of the phosphate heads
- termed peripheral proteins
- or passes through one or both lipid layers
- termed integral proteins
whats the mnemonic for the functions of integral and peripheral proteins in the membrane?
CC CHIP
whats does the mnemonic for the functions of integral and peripheral proteins in the membrane stand for?
- Cell to cell adhesion proteins (i)
- Cell to cell communication proteins (i and p)
- Channel proteins (i)
- Hormone receptors (i)
- Immobilized enzymes (i)
- Pump proteins (i)
describe the freeze fracture electron microscopy experiment
- cells were frozen to stop any potential movement in the membrane and broke the sample apart to visualise the membrane’s internal structure
- lipid bilayer has dark indentations suggesting that proteins where integrated in the membrane in addition to being found on its outside
