Membranes Flashcards
what are the 3 main functions of a plasma membrane?
- control transport of substances in and out of the cell
- act as a receptor site
- separate the cell from its environment
what substances can enter and leave a cell ?
- oxygen
- carbon dioxide
- glucose
- mineral ions
- water
- amino acids
- urea
why can membranes allow substances to pass through ?
they are partially permable
what surrounds a Eukaryota cell
plasma membrane
what are plant and prokaryotic cells surrounded by?
a cell wall
why can all molecules move through a cell wall ?
it is a freely permeable, and contains large pores
what does a membrane contain?
- phospholipids
- membrane protiens
- glycolipids
- cholesterol
what don’t membranes let pass through?
water soluble, charged or polar substances
what do phospolipids form in water?
a bilayer
what does the bilayer do ?
acts as a barrier to polar, charged, and water soluble molecules
it allows non polar, uncharged and soluble molecules to pass through
which substances would be able to move through these hydrophilic channels?
charge molecules such as ion and water
what are glycoprotiens ?
short, branching carbohydrate chains are attached to proteins
what do glycoprotiens act as?
- receptors for hormones and neurotransmitters#
- antigens
what do glycolipids act as?
- recognition sites
- help maintain the stability of the membrane and help attach to one another (form tissues)
what are glycolipids made up of?
a carbohydrate covalently bonded to a lipid
