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biological molecules Flashcards

2.7 - 2.14B

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1
Q

2.7 the chemical elements present in carbohydrates

A

carbon, hydrogen and oxygen
(C,H,O)

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2
Q

2.7 the chemical elements present in proteins

A

carbon, hydrogen, oxygen and nitrogen
(C,H,O,N)

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3
Q

2.7 the chemical elements present in lipids (fats&oils)

A

carbon, hydrogen and oxygen
(C,H,O)

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4
Q

2.8 starch and glycogen is from

A

simple sugars

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5
Q

2.8 protein is from

A

amino acids

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6
Q

2.8 lipids are from

A

fatty acids and glycerol

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7
Q

2.8 a monosaccharide is a …

A

simple sugar like glucose

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8
Q

2.8 a disaccharide is made when

A

two monosaccharides join together e.g. maltose = glucose & glucose
sucrose = glucose & fructose

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9
Q

2.8 a polysaccharide is formed when

A

lots of monosaccharides join together

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10
Q

2.8 polysaccharides starch, glycogen or cellulose are all formed when

A

lots of glucose molecules join together

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11
Q

2.8 most fats (lipids) in the body are made up of

A

triglycerides

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12
Q

2.8 lipids basic unit is

A

one glycerol molecule chemically bonded to three fatty acid chains

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13
Q

2.8 proteins are formed from

A

long chains of amino acids

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14
Q

2.8 when amino acids are joined together

A

a protein is formed

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15
Q

2.9 what is the test for starch?

A

iodine solution

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16
Q

2.9 explain the test for starch

A
  1. place food sample on a spotting tile
  2. add a few drops of iodine solution to the sample
  3. blue - black colour indicates starch
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17
Q

2.9 what is the test for glucose / reducing sugars?

A

benedicts solution

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18
Q

2.9 explain the test for glucose / reducing sugars?

A
  1. place food sample in a boiling tube
  2. add benedict’s solution to the sample of food in solution
  3. place in a water bath at 80*c for 5 minutes
  4. a change from blue to brick red if present
    (if green, yellow or orange means less sugar present)
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19
Q

2.9 what is the test for protein?

A

biuret test

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20
Q

2.9 explain the test for protein

A
  1. place food sample in a boiling tube
  2. add enough biuret solution for colour to be pale blue
  3. if protein is present colour will change to mauve / purple
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21
Q

2.9 what is the test for lipids?

A

emulsion test

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22
Q

2.9 explain the test for lipids?

A
  1. place food sample in a test tube
  2. add small amount of ethanol and shake to dissolve any lipid in the alcohol.
  3. add equal volume of water
  4. cloudy white colour (emulsion will form) indication presence of lipid
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23
Q

2.9 benedicts solution is used to test for

A

reducing sugars (glucose)

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24
Q

2.9 benedicts solution colour change

A

blue to brick red

25
Q

2.9 how do I remember benedicts solution

A

christmas sugar

26
Q

2.9 iodine is used to test for

A

starch

27
Q

2.9 iodine solution colour change

A

orange to blue-black

28
Q

2.9 how do I remember iodine

A

bumblebee

29
Q

2.9 biuret is used to test for

A

protein

30
Q

2.9 biuret solution colour change

A

(light)blue to pale purple

31
Q

2.9 how do I remember biuret

A

snowflakes
(et) proTEin biurET

32
Q

2.9 emulsion is used to test for

A

lipids

33
Q

2.9 emulsion colour change

A

colourless to a cloudy white emulsion

34
Q

2.9 how do I remember emulsion

A

snowing

35
Q

2.10 enzymes are biological

A

catalysts

36
Q

2.10 a catalyst is a ……..

A

chemical which increases the rate of a reaction without being used up itself in the reaction

37
Q

2.10 the theory for understanding how enzymes work is the

A

lock and key theory

38
Q

2.10 what is the lock and key theory

A

the substrate and enzyme collide,
the substrate binds to the active site of the enzyme,
(the reaction occurs by an alternative pathway with a lower activation energy)
once the reaction occurs, the products don’t fit - so they are released,
the enzyme is free to catalyse the next reaction

39
Q

2.10 the active site has a particular shape which is … to the shape of the substrates

A

complementary

40
Q

2.10 because the shape of the active site is complementary to that of the substrates, this means

A

each enzyme can only catalyse one reaction

41
Q

2.11 as temperature increases the enzyme & substrate have more

A

kinetic energy
so they move faster and there are more successful collisions

42
Q

2.11 high temperatures and changes of pH cause the shape

A

to change

43
Q

2.11 when the shape changes we say this is

A

the protein being denatured

44
Q

2.11 when the active site changes shape it is no longer

A

complementary to the substrate

45
Q

2.12 practical for investigating effect of temperature on enzymes

A

place spots of iodine into each dip of a spotting tile
add 5cm^3 of starch suspension into a boiling tube w/ a syringe
with a different syringe add 5cm^3 of amylase solution into another tube
fill a beaker w/ water at 20C & place both boiling tubes inside for 5 minutes
pour amylase solution into the starch suspension leaving it in the water bath
take a sample w/ pipette & add a drop to the iodine solution in the spotting tile
record colour change of the solution in the tile
repeat every 30 seconds for 10 minutes
until the iodine solution remains orange indicating the starch is used up
repeat the experiment with the water bath at diff temps between 20C & 60*C

46
Q

2.13 what is the optimum pH for most enzymes

A

7

47
Q

2.13 which enzymes have a lower pH than 7

A

those produced in acidic conditions e.g. the stomach
- pH 2

48
Q

2.13 which enzymes have a higher pH than 7

A

those produced in alkaline conditions e.g. the duodenum - pH 8/9

49
Q

2.13 what happens if the pH is too high or too low

A

the bonds that hold the amino acid chain together can be disrupted / destroyed
this changes the shape of the active site
so the substrate can no longer fit into it
this reduces the rate of activity
moving too far away from the pH - the enzyme will denature

50
Q

2.14B practical investigating how enzyme activity can be affected by changes in pH

A

add a drop of iodine to each well of a spotting tile
use a syringe to place 2cm^3 of amylase into a test tube
add 1cm^3 of buffer solution (at pH2) to the same test tube using a syringe
in another test tube add 2cm^3 of starch solution
pour the starch solution into the amylase and buffer solution
start a stopwatch whilst mixing the solution using a pipette
every 10 seconds transfer a droplet of the solution to a new well of iodine solution which should turn blue black
repeat every 10 seconds until the iodine solution stops turning blue-black
meaning the amylase has broken down all the starch
record the time taken for reaction to be completed
repeat the investigation with buffers at different pH values from pH3 - pH7

51
Q

2.14B practical amylase is an enzyme that breaks down

A

starch into maltose

52
Q

2.14B practical what does it mean when the iodine solution remains orange - brown

A

that all the starch has broken down

53
Q

2.14B practical what will this investigation show

A

at the optimum pH the iodine stopped turning blue-black within the shortest amount of time

54
Q

2.14B practical why does the iodine remain orange in the shortest amount of time

A

because the enzyme is working at its fastest / optimum rate and has digested all of the starch

55
Q

2.14B practical what will happen at a higher or lower pH

A

the iodine will take longer to stop turning blue-black

56
Q

2.14B practical what is a control variable

A

the starch and amylase solutions should be placed in a water bath at the optimum temperature before being used

57
Q

2.14B practical name one tool that can be used to measure the progress of the reaction more accurately

A

using a colorimeter

58
Q

2.14B practical CORMS

A

C - changing the pH of the environment
O - not relevant - no organism
R - repeat several times to ensure reliability
M - measure time taken for iodine to stop turning blue-black
S - control the concentration & volume of the amylase, iodine and starch solution

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