lipids 2 : phospholipids and cholesterol Flashcards
define phospholipid
molecule consisting of glycerol , 2 fatty acids and one phosphate group
what is the difference between phsopholipid and triglyceride ?
one of the fatty acids is replaced by a phosphate group
what happens during the reaction for a phospholipids to form ?
- a condenstaion reaction occurs
- between an OH group on a phosphoric acid molecule (H3PO4)
+ - one of the 3 -OH groups on the glycerol forms an ester bond
what do most fatty acids found in phospholipids have carbon atoms ?
an even number (often 16 or 18)
what is commonly found within these chains ?
saturated and one of them unsaturated
draw a phospholipid
found in textbook
how does the phosphate group react to water ?
- has a negative charge
–> making it polar (attracted to water )
how does the fatty acid tails react to water ?
- no charge
are non-polar (repelled by water)
what is it common to refer the head and tail as?
head - hydrophilic
tails - hydrophobic
what is the phospholipid molecule referred as ?
amphipathic
when are membrane lipids not A ?
when they aren’t involved in storage
what do phospholipids form and how ?
- form a layer on the surface of water - with heads in the water
+ - tails sticking up out of the water
- they may form micelles
( tiny balls with tails tucked away inside + heads pointing outwards into the water )
what are phospholipids excellent at forming ?
- membranes –> around cells and organelles
what is inside and outside a cell membrane ?
an aqueous solution
what do phospholipids form and how ?
a bilayer
–> 2 rows of phospholipids
–>tails pointing inwards and heads pointing outwards into the solution
what is the percentage of membranes in plant and animal cells are made of phospholipids ?
-between 20 to 80 %
what do bacterial membranes tend to contain ?
a greater proportion of protein
what are individual phospholipids allowed to do but may not …?
- are free to move around in their layer
- but won’t move into any position where their hydrophobic ails are exposed to water
- which gives the membrane some stability
draw a micelle
found in textbook :)
draw a bilayer
found in textbook :)
what is the membrane described as ?
selectively permeable
what is possible to move through the tails and why is this important ?
- it s only possible for small and non polar molecules to move through the tails in the bilayer ( such as oxygen and carbon dioxide )
- this lets the membrane control what goes in and out of the cell , and keeps it functioning properly
what is cholesterol ?
a steroid alcohol
what is cholesterol not made of but is ?
- fatty acids and glycerol
- a LIPID
