pack 3 lipids Flashcards
(19 cards)
elements in lipids
\carbon, hydrogen, oxygen
saturated fatty acids
no double bonds between carbons
- solid at room temp
unsaturated fatty acids
one or more double bonds between carbons
- liquid at room temp
glycerol
3 hydroxly groups
formation of a triglyceride
condensation reaction producing 3 water molecules
- bonds formed between OH- - hydroxyl group and COOH carboxyl group
- easter bonds
triglyceride biological roles
- storage of energy
- insulation
- protection
the structure and properties of triglycerides related to their function
- they have a high ration of energy storing carbon-hydrogen bonds to carbon atoms and therefore an excellent source of energy
- they are low mass to energy ratio making them good storage molecules because so much energy can be stored in a small volume
- they are large, non polar molecules, insoluble in water so they have no osmotic effect and do not affect the water potential in cells
plasma membrane- function and importance
1) to control the transport of substances into and out of the cell or organelles
- membrane allows certain molecules to pass through but not others
2) to act as a receptor site to recognise chemicals which need to enter the cell or organelles
- allows cells to communicate and react to their environments
3) to compartmentalise, separate off the cell from the environment, and the different reactions of the cell from each other by forming the organelles
- allows reactions to occur more efficiently
phospholipids
- phospholipids are lipids in which one of the fatty acids is substituted for a phosphate group.
composed of - a polar/hydrophillic head (glycerol and phosphate)
- a non-polar tails (fatty acids)
what does the phospholipid bilayer do
- acts as a barrier to polar/charged molecules
- it allows non- polar/ uncharged molecules to pass through
membrane proteins
- membrane is about 7mm wide and is a fluid structure. it has molecules floating in the bilayer, forming a fluid mosaic structure
-proteins may be one layer ( extrinsic) or across the whole membrane (intrinsic)
glycoproteins
- short, branching carbohydrate chain are attached to proteins in the membrane
- these glycoproteins act as receptors for hormones and neurotransmitters or antigens.
glycolipids
- these are made up of a carbohydrate covalently bonded to a lipid
- they act as recognition sites, help to maintain the stability of the membrane and help cells attach to one another,
cholesterol
- this restricts the movement of other molecules making up the membrane and increases strength and stability of membranes by making them less flexible
- it helps to prevent the loss of water and dissolved ions from the cell
simple diffusion
- diffusion is the net movement of particles down a concentration gradient from a region of high to low
- as a result of diffusion substances tend to reach a dynamic equilibrium - evenly spread out
ficks law
rate of diff = surface area times difference in concentration / thickness of exchange surface
facilitated diffusion
- movement down a concentration gradient requires carrier/ channel proteins
- rate of facilitated diffusion may be limited by number of carriers
- passive process
- used to move charged polar substances
active transport
- against the concentration gradient
- the cells uses carrier proteins to pump these substances across the membrane
- this process requires the expenditure of energy in the form of atp
osmosis
- movement of water across a partially permeable membrane down a water potential gradient from higher to lower water potential
