CB2 Flashcards
(15 cards)
what is the cell membrane made up of?
the cell membrane is made up of phospholipids and protein.
how are the parts of the cell membrane arranged?
the phospholipids form a bi-layer and the proteins are scattered through this bi-layer.
what does the term ‘selectively permeable’ mean?
selectively permeable means that some, small molecules can cross easily, whilst other, larger molecules are prevented from crossing.
what colours/tests are associated with iodine and benedicts?
iodine: tests for starch, turns black when starch is present
benedicts: tests for glucose, turns orange when glucose is present.
give some examples of molecules which can/can’t cross the cell membrane:
CAN: water molecules, gas molecules, molecules of soluble foods (glucose, amino acids etc)
CAN’T: molecules of insoluble foods (e.g starch)
definition of diffusion:
the movement of molecules down a concentration gradient from high concentration to low concentration.
why is diffusion important?
diffusion is important to cells because it allows them to gain the substances they require to obtain energy and grow. It also lets them get rid of waste products.
definition of osmosis:
the movement of water molecules down a concentration gradient through a selectively permeable membrane.
what is active transport?
active transport is the movement of substances againt the concentration gradient (low concentration > high concentration).
what does active transport require?
active transport requires energy (ATP) and will often require a membrane protein.
give an example of active transport:
NaK pump- occurs in nerve cells and moves sodium and potassium from low to high concentration.
give an example of diffusion:
nutrients diffusing into bloodstream
define the terms ‘turgid’ and ‘plasmolysed’.
turgid: plant cell that has gained water by osmosis.
plasmolysed: plant cell that has lost water by osmosis
what is passive transport?
a form of transport which requires no energy.
what is the difference intracellular/extracellular environment?
intracellular= inside cell
extracellular= outside cell
