Biological Molecules AS Flashcards

Question

Explain the structure of a phospholipid

Answer 1

glycerol backbone with 2 fatty acids and one phosphate group fatty acid tails are hydrophobic phosphate group is hydrophilic

Answer 2

- Mainly used as energy storage molecules they are good for this as the long hydrocarbon tails of the fatty acids contain a lot of chemical energy - a lot of energy is released when broken down - insoluble in water so don't effect water potential - triglycerides bundle together as insoluble droplets in cells as fatty acid tails are hydrophobic - tails face inwards shielding themselves from water with their glycerol heads

Answer 3

- make up the bilayer of cell membranes - this controls what enters and leaves a cell -heads are hydrophilic and tails are hydrophobic so they form a double layer with heads facing outwards - the centre of the bilayer is hydrophobic so water soluble substances cant easily pass through - the membrane acts as a barrier to those substances

Answer 4

Emulsion test - Shake test substance with ethanol for a minute, then pour the solution into water - any lipid will show as a milky emulsion - the more lipid there is the more noticeable the milky colour will be

Answer 5

amino acids

Answer 6

polypeptide

Answer 7

polypeptides

Answer 8

condensation reactions peptide bond

Answer 9

sequence of amino acids in the polypeptide chain

Answer 10

Hydrogen bonds form between amino acids in the chain This makes it automatically coil into alpha helix or beta pleated sheet

Answer 11

More bonds form between different parts of the polypeptide chain including hydrogen bonds and ionic bonds. Disulfide bridges also can form For proteins with one polypeptide chain, this is their final 3D structure

Answer 12

Some proteins are made of several polypeptide chains held together by bonds. The way these are held is the quaternary structure e.g. haemoglobin, insulin and collagen final 3D structure

Answer 13

Haemoglobin is compact and soluble which makes it easy for transport. This makes them good for transport of oxygen Antibodies = two light and 2 heavy polypeptide chains - these have variable regions Enzymes = roughly spherical in shape due to tight folding, soluble and often have roles in metabolism and other enzymes help to synthesise large molecules

Answer 14

1. test solution needs to be alkaline, so first you add a few drops of sodium hydroxide solution 2. then you add some copper (II) sulfate solution if positive purple colour if negative solution stays blue

Answer 15

proteins Enzymes have an active site which has a specific shape. This is where the substrate molecule binds to the enzyme. Enzymes are highly specific due to tertiary structure.

Answer 16

Lower the activation energy by providing an alternative pathway

Answer 17

- if two substrate molecules need to be joined, being attached to an enzyme holds them close together, reducing any repulsion between the molecules so they can bond more easily - if the enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on bonds in the substrate so the substrate molecule breaks up more easily

Answer 18

Substrate fits directly into the enzyme the way a key fits into a lock - the active site and substrate have a complimentary shape

Answer 19

The substrate doesn't only have to be the correct shape to sit the active site, it has to make the active site change shape as well As the substrate binds to the active site, the active site changes shape slightly

Answer 20

The shape of the active site will change and the substrate will therefore not be able to fit into active site - preventing the formation of an enzyme-substrate complex and the enzyme cannot carry out the function. The structure may be altered by pH or temperature If there is a mutation in a gene in the primary structure it could change the tertiary structure of the enzyme produced

Answer 21

1. how fast the product is made - measure amount of end product present at different times in the reaction 2. how fast the substrate is broken down - measure amount of substrate molecules present at different times in the reaction

Answer 22

Increased temp means more kinetic energy so the substrate molecules are more likely to collide with the enzyme active sites. The energy of these collisions also increases which means each collision is likely to result in a reaction. If temp goes too high, the active site changes shape and the enzyme substrate can no longer fit - the enzyme is denatured and no longer can function as a catalyst

Answer 23

All enzymes have an optimum pH value, most human enzymes work at pH 7 but others are an exception such as pepsin which is pH 2 Levels above and below the optimum pH can disrupt the ionic and hydrogen bonds that hold the enzymes tertiary structure in place The enzyme become denatured and the active site changes

Answer 24

The higher the substrate concentration the faster the reaction as more collisions between substrate and enzyme After the saturation point, there is not enough enzymes to cope with all of the substrates so adding more makes no difference

Answer 25

More enzymes = more likely a substrate will collide to form an enzyme substrate complex therefore increasing rate of reaction If amount of substrate is limited, there aren't enough to bind with all of the enzymes - so adding more enzyme has no further effect

Answer 26

Have a similar shape to the substrate molecule. They compete with the substrate molecules to bind to the active site so no reaction takes place. They prevent substrates binding by blocking the active site Increasing the concentration of substrate will increase the rate of reaction as the substrate will have better chance at binding with the substrate.

Answer 27

Bind to the enzymes away from the active site which causes the active site to change shape so the substrate molecules can no longer bind to it. Increasing the conc of substrate will have no effect as they don't compete with the substrate.