Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
16 Cards in this Set
- Front
- Back
|
what type of structure does the cell membrane have? |
composed of lipids - mainly phospholipids --> lipid + phosphate group attached to it. |
|
|
what is the name of the arrangement of molecules in a membrane |
fluid mosaic model |
|
|
describe the fluid mosaic model |
phospholipid molecules form a continuous layer - (bilayer). the bilayer is fluid because the phospholipids are constantly moving |
|
|
why is the fluid model mosaic? |
the proteins are scattered like tiles in a mosaic... due to the fluidity the proteins can move around |
|
|
what do some proteins in the fluid mosaic model have attached to them |
a polysaccharude chain called glycoprotein |
|
|
what do some lipids have attached to them ? |
a polysaccharude cahin called glycolipid |
|
|
apart from phospholipids and glycolipids what other lipid does the fluid mosaic model contain ? |
cholesterol |
|
|
what is the role of cholesterol in the plasma membrane |
fits between phospholipids forming bonds and makes the membrane more rigid |
|
|
why is the plasma membrane partially permeable? |
small molecules can move through the gaps between phospholipids but large molecules can onlt pass through special membrane proteins called channel proteins and carrier proteins |
|
|
how could you test the permability of the cell membrane |
doing the beetroot experiement. |
|
|
how would the beetroot experiment show the permability of the cell membrane |
beetroot cells contain coloured pigment that leaks out- the higher the permability of the membrane the more pigmnet leaks out of the cell |
|
|
name the 5 steps of the beetroot experiment |
1. cut 5 equal sizes of beetroot and rinse them off the remove pigment released during the cutting. 2.place 5 different pieces into 5 different test tubes with 5cm(cubed) of water 3. place each test tube in different temperatures eg. 10, 20, 30, 40, 50,for the same length of time 4. remove the pieces of beetroot from the test tubes leaving the colouring liquid 5. use a colourimeter - machine passes light throught eh liquid and measure how much light was absorbed - |
|
|
what happens to phospholipids at 0 degrees |
-phospholipids have no energy - not much movement. -closely packed together - rigid. - chan and carr proteins deform ,inc permeability. - ice crystals may form - may pierce the membrane - |
|
|
what happens to phospholipids at 0-45 degrees |
phospholipids can move - not tightly packed. as the temp inc phospholipids move due to more energy ---> ince permeability of the membrane |
|
|
what happens to the phospholipids at 45+ |
phospholipid bilayer start to melt .---> more permeable. water inside cells expands ---> more pressure chan and carr proteins deform ---> no control over what enters and leaves the cell |
|
|
why can you test permability of the cell membrane using alcohol |
alcohol dissolves the lipids in the cell membrane ---> it loses its structure |
