1.3 Membrane structure Flashcards
What does hydrophilic mean?
A substance attracted to water
What does hydrophobic mean?
A substance not attracted to water
What does amphipatic mean?
A substance that is partially hydrophilic and partially hydrophobic
Why are phospholipids amphipatic?
They consist of a hydrophilic phosphate head and two hydrophobic hydrocarbon tails
Why are phospholipids arragned in a bilayer
Because they are amphipatic. The heads are attracted to water whereas the hydrocarbon chains are attracted to eachother
Draw a phospholipid
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Draw the phospholipid bilayer
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Davson-Danielli model
Their “sandwich” model believed that all membrane proteins were on the outside of the membrane. Due to advancments in biochemical techniques it was, however, discovered that some membrane proteins are hydrophobic, which falsified the Davson-Danielli model
The fluid mosaic model
The model was proposed by Singer and Nicolson. It states that proteins are both on the surface of the membrane but also embedded in the membrane.
What are peripheral membrane proteins?
Proteins that are on the membrane surface. They can be attached to integral proteins or have a hydrocarbon chain inserted into the membrane
What are integral proteins?
Proteins that are embedded in the membrane. Many are transmembrane meaning that the extend across the membrane. These proteins have hydrophilic parts projecting through the regions with phosphate heads.
Explain cholesterol in the cell membrane
Cholesterol is present in the cell membranes of animal cells. They have a hydrophobic part and a hydrophilic part, and for this reason it is located between phospholipids in the membrane. Cholesterol can help the membrane to curve into a concave shape, which helps with the formation of vessicles
Draw the cell membrane/fluid mosaic model
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